Oceanography Glossary Definitions
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Complete list of Terms and Definitions for Oceanography Glossary Definitions

Terms Definitions
polar easterlies Winds blowing from the poles toward approximately 60°N and 60°S; winds are northeasterly in the north hemisphere and southeasterly in the south hemisphere.
estuary A body of water partially surrounded by land where fresh water from a river mixes with ocean water, creating an area of remarkable biological productivity.
auxospore A naked diatom cell without valves. Often a dormant stage in the life cycle following sexual reproduction.
orbital wave A progressive wave in which particles of the medium move in closed circles.
contour current A bottom current made up of dense water that flows around (rather than over) seabed projections.
alluvial plain A flat deposit of terrestrial sediment eroded by water from higher elevations.
chlorinity A measure of the content of chloride, bromine, and iodide ions in seawater. We may derive salinity from chlorinity by multiplying by 1.80655.
brackish Describing water intermediate in salinity between seawater and freshwater.
polar easterlies Winds blowing from the poles toward approximately 60°N and 60°S; winds are northeasterly in the north hemisphere and southeasterly in the south hemisphere.
bykill Animals unintentionally killed when desirable organisms are collected.
fault A fracture in a rock mass along which movement has occurred.
salt marsh An area of soft, wet land periodically covered by saltwater, in temperate zones and generally treeless with characteristic salt-tolerant plants such as reeds and samphire.
ice floe A mass of firm sea ice floating as a unit.
absolute dating Determining the age of a geological sample by calculations of radioactive decay and/or its position in relation to other samples.
crustal plate A segment of Earth's surface. Continental plates are about 25 miles thick and oceanic plates 3.1 miles thick.
corange lines In a rotary tide, lines of equal tidal range about the amphidromic point.
Bay of Nice Located in the north western Mediterranean basin.
bathymetry The discovery and study of submerged contours.
perihelion The point in the orbit of a satellite where it is closest to the sun; opposite of aphelion.
Asteroidea The class of the phylum Echinodermata to which sea stars belong.
big bang The hypothetical event that started the expansion of the universe from a geometric point. The beginning of time.
foreshore Portion of the shore that includes the low-tide terrace and the beach face.
ionic bond A chemical bond resulting from attraction between oppositely charged ions. These forces are said to be "electrostatic" in nature.
tidal period Elapsed time between successive high waters or successive low waters.
law A large construct explaining events in nature that have been observed to occur with unvarying uniformity under the same conditions.
seasonality The timing of major biological events cued by changes in light intensity and water temperature associated with the seasons in temperate latitudes.
beach A zone of unconsolidated (loose) particles extending from below water level to the edge of the coastal zone.
Celebes Sea Alternate name for the Sulawesi Sea.
protozoa Multiphyletic animal group within the kingdom Protista. Protozoa include amoebas, paramecia, foraminiferans, and radiolarians.
Polychaeta The largest and most diverse class of phylum Annelida. Nearly all polychaetes are marine.
net circulation The long-term transport of water out of an estuary at the surface and into the estuary at depth averaged over many tidal cycles.
barrier layer the layer between the thermocline and the halocline
cosmogenous sediment Sediment of extraterrestrial origin.
abyssal storm Storm-like occurrences of rapid current movement affecting the deep ocean floor. They are believed to be caused by warm- and cold-core eddies of surface currents.
galaxy A large rotating aggregation of stars, dust, gas and other debris held together by gravity. There are perhaps 50 billion galaxies in the universe and 50 billion stars in each galaxy.
sediment A navigational instrument used to measure angles between the moon, sun, stars, and objects such as the horizon; Fine organic or material particles found in the seafloor.
amphidromic point A "no-tide" point in an ocean caused by basin resonances, friction, and other factors around which tide crests rotate. About a dozen amphidromic points exist in the world ocean. Also sometimes called a node.
heat budget An expression of the total solar energy received on Earth during some period of time and the total heat lost from Earth by reflection and radiation into space during the same period.
sideral day Time period determined by one rotation of earth relative to a far-distant star, about four minutes shorter than the mean solar day.
shelf sea The shallow but often highly productive seas over continental shelves.
benthic zone The seabed.
bioturbation Reworking of sediments by organisms that burrow into them and ingest them.
bloom The sudden increase in phytoplankton number, usually associated with season changes.
pelagic zone The realm of open water. See also benthic zone: the seabed.
Baltic Sea A dilution basin type of Mediterranean sea that is connected to and experiences limited, intermittent water exchange with the North Sea.
paleomagnetism The "fossil", or remanent, magnetic field of a rock.
Mammalia The class of animals.
floe Discrete patch of sea ice moved by the currents or wind.
Ekman spiral A theoretical model of the effect on water of wind blowing over the ocean. Because of the Coriolis effect, the surface layer is expected to drift at an angle of 45° to the right of the wind in the Northern hemisphere and 45° to the left in the Southern Hemisphere. Water at successively lower layers drifts progressively to the right (N) or left (S), though not as swiftly as the surface flow.
Pacific Ring of Fire The zone of seismic and volcanic activity that encircles the Pacific Ocean.
acoustical tomography A technique for studying ocean structure that depends on pulses of low frequency sounds to sense difference in water temperature, salinity, and movement beneath the surface.
beach face The sloping section of a beach profile below the beach berm which is normally exposed to the action of the wave swash.
biological factor A biologically generated aspect of the environment, such as predation or metabolic waste products, that affects living organisms. Biological factors usually operate in association with purely physical factors such as light and temperature.
Arthropoda The phylum of animals that includes shrimp, lobsters, krill, barnacles, and insects. The phylum Arthropoda is the world's most successful.
Nansen bottle A water sampling instrument invented in 1910 by the Norwegian scientist and explorer Fridtjoj Nansen.
compass An instrument for showing direction by means of a magnetic needle swinging freely on a pivot and pointing to magnetic north.
isobath Contour of constant depth.
sphere depth Thickness of a material spread uniformly over a smooth sphere having the same area of earth.
polar wandering curve A plot of the apparent location earth's north magnetic pole as a function of geologic time.
biodegradable Able to be broken by natural processes into simpler compounds.
condensation theory Premise that stars and planets accumulate from contracting, accreting clouds of galactic gas, dust, and debris.
climate The long-term average of weather in an area.
relict sediments Sediments deposited by processes no longer active.
bathyscaphe Deep-diving submersible designed like a blimp, which uses gasoline for buoyancy and can reach the bottom of the deepest ocean trenches.
bathyal zone The marine ecologic zone that lies deeper than the continental shelf but shallower than the deep ocean floor, i.e. those depths corresponding to the locations of the continental slope and rise.
crustaceans Invertebrates with jointed limbs and hard chalky shells, such as lobsters, crabs, and shrimp.
carbonate compensation depth (CCD) Also known as the calcite compensation depth, is the depth at which the amount of calcium carbonate preserved falls below 20% of the total sediment. This is also commonly defined as the depth at which the amount of calcium carbonate produced by organisms skeletal material in the overlying water column is equal to the rate at which it is dissolved in the water. No calcium carbonate will be deposited below this depth.
mean earth sphere depth The depth below sea level of the surface of the solid earth if it was perfectly smooth with no variation in elevation. This is 2403 m (7884 ft) below present sea level.
continental rise Gently sloping base of the continental slope.
active margin Continental margin near an area of lithospheric plate convergence. Also called Pacific Type Margin.
osmoregulation The ability to adjust internal salt concentration.
interference Addition or subtraction of wave energy as waves interact. Also called resonance. See also constructive interference; destructive interference.
ooze Sediment of at least 30% biological origin.
isobar Line of equal, or constant, pressure
beach scarp Vertical wall of variable height marking the landward limit of the most recent high tides.
terranes Fragments of earth's crust bounded by faults, each fragment with a history distinct from each other fragment.
principle of constant proportions The proportions of major conservative elements in seawater remain nearly constant, though total salinity may change with location. Also called Forchhammer's principle.
continental shelf break Zone along which there is a marked increase of slope at the outer margin of a continental shelf.
cartilage A tough, elastic tissue that stiffens or supports.
agar Substance produced by red algae; the gelatin-like product of these algae.
beta refraction An effect that results from the latitudinal variation of Rossby wave phase speed which is, in turn, due to the beta effect. If a line of Rossby waves were started along a straight eastern ocean boundary, then those at low latitudes would arrive at the western boundary before those at high latitudes.
meteorological equator The irregular imaginary line of thermal equilibrium between hemispheres. It is situated about 5° north of the geographical equator, and its position changes with the seasons, moving slightly north in northern summer. Also called the thermal equator.
world ocean The great body of saline water that covers 70.78% of Earth's surface.
breaker zone The portion of the nearshore zone where waves arriving from offshore become unstable and break
photic zone The thin film of lighted water at the top of the world ocean. The photic zone rarely extends deeper than 200 meters (660 feet). See also euphotic zone.
cold seep Cold seawater, rich in methane, hydrogen sulfide, and hydrocarbons issuing from the seafloor.
paleoceanography The study of the ocean's past.
macroplankton Animal plankters larger than 1 to 2 centimeters ( 1/2 to 1 inch). An example is the jellyfish.
bacteria Single-celled prokaryotes, organisms lacking membrane-bound organelles.
deadweight ton (DWT) Capacity of a vessel in tons of cargo, fuel, stores, and so on; determined by the weight of the water displace.
mean ocean sphere depth The depth of the ocean if the solid earth was perfectly smooth with no variation in elevation. This is 2646m (8642 ft.)
radar Radio Detection and Ranging- the use of pulsed radio waves to follow moving objects by analyzing changes in reflected radio signals.
bar Offshore ridge or mound of sand, gravel, or other loose material that is submerged, at least at high tide; located especially at the mouth of a river or estuary or lying a short distance from and parallel to the beach; A submerged or emerged mound of sand, gravel, or shell material built on the ocean floor in shallow water by waves and currents.
erosional coast A coast in which erosive processes exceed depositional ones.
supersaturation When the concentration of a dissolved substance is higher than its normal saturation value.
Perigean Tide A monthly tide of increased range that occurs when the moon is closest to earth (at perigee).
calcareous Of or containing calcium carbonate or another, usually insoluble, calcium salt.
basalt The relatively heavy crustal rock that forms the seabeds, composed mostly of oxygen, silicon, magnesium, and iron. Its density is about 2.9 g/cm3.
armored beach A beach that is protected from wave and water erosion by coarse-size lag deposits.
island arc Curving chain of volcanic islands and seamounts almost always found paralleling the concave edge of a trench.
agar Substance produced by red algae; the gelatin-like product of these algae.
thermohaline circulation Water movement caused by differences in density produced by salinity and/or temperature changes.
photon The smallest unit of light energy.
andesite A volcanic rock intermediate in composition between basalt and granite; associated with subduction zones.
metrophagy Tendency for large reptiles to eat entire cities.
alluvial plain A flat deposit of terrestrial sediment eroded by water from higher elevations.
chemical equilibrium In seawater, the condition in which the proportion and amounts of dissolved salts per unit volume of ocean are nearly consistent.
Asteroidea The class of the phylum Echinodermata to which sea stars belong.
cnidoblast Type of cell found in members of the phylum Cnidaria that contains a stinging capsule. The threads that evert from the capsules assist in capturing prey and repelling aggressors.
euphotic zone The upper layers where light is sufficient for photosynthesis.
Blade Algal equivalent of a vascular plant's leaf. Also called a frond.
polar molecule A molecule with unbalanced charge. One end of the molecule has a slight negative charge, and the other end has a slight positive charge.
Cephalopoda The class of the phylum Mollusca that includes squid, octopuses, and nautiluses.
trench A narrow, deep depression in the ocean floor, often associated with the subduction of an oceanic plate at a continental margin.
benthos Organisms living on or in the ocean bottom.
carrying capacity The size at which a particular population in a particular environment will stabilize when its supply of resources--including nutrients, energy and living space -- remains constant.
convection cell Circulation in a fluid, or fluidlike material, caused by heating from below. Heating the base of a fluid lowers its density, causing it to rise. The rising fluid cools, becomes denser, and sinks, creating circulation.
Columbus, Christopher 1451-1506. Italian explorer in the service of Spain who discovered islands in the Caribbean in 1492. Although traditionally credited as the discoverer of America, he never actually sighted the North American continent.
delta The deposit of sediments found at a river mouth, sometimes triangular in shape (hence the name after the Greek letter).
compensation depth The depth in the water column at which the production of carbohydrates and oxygen by photosynthesis exactly equals the consumption of carbohydrates and oxygen by respiration. The break-even point for autotrophs. Generally a function of light level.
float method A method of current study that depends on the movement of a drift bottle or other free-floating object.
apogee The point in the orbit of a satellite farthest from the main body; opposite of perigee.
submersible A research submarine, designed for manned or remote operation at great depths.
carbon-14 dating A radioisotope dating method wherein a radioactive isotope of carbon, also called radiocarbon, is used to date materials containing carbon.
calving Breaking away of a mass of ice from its parent glacier, iceberg, or sea ice formation.
passive margin Continental margin near an area of lithospheric plate divergence. Also called Atlantic-type margin.
sea cow (dugong, manatee) Large, herbivorous marine mammal of tropical and subtropical waters.
acoustical tomography A technique for studying ocean structure that depends on pulses of low frequency sounds to sense difference in water temperature, salinity, and movement beneath the surface.
hypothesis A speculation about the natural world that may be verified or disproved by observation and experiment.
absolute dating Determining the age of a geological sample by calculations of radioactive decay and/or its position in relation to other samples.
Pinnipedia The carnivoran suborder that contains the seals, sea lions, and walruses.
Coriolis effect The apparent deflection of a moving object from its initial course when its speed and direction are measured in reference to the surface of the rotating Earth. The object is deflected to the right of its anticipated course in the Northern hemisphere and to the left in the Southern Hemisphere. The deflection occurs for any horizontal movement of objects and has no effect at the equator.
chlorofluorocarbons A class of halogenated hydrocarbons thought to be depleting Earth's atmospheric ozone. CFCs are used as cleaning agents, refrigerants, fire extinguishing fluids, spray can propellants, and insulating foams.
Carnivora The order of mammals that includes seals, sea lions, walruses, and sea otters.
outgassing The volcanic venting of volatile substances.
Aves The class of birds.
Baguio The local name given to tropical cyclones in the Philippines, especially those occurring from July to November.
ion An atom (or small group of atoms) that becomes electrically charged by gaining or losing one or more electrons.
density curve A graph showing the relationship between a fluid's temperature or salinity and its density.
bathyscaphe Deep-diving submersible designed like a blimp, which uses gasoline for buoyancy and can reach the bottom of the deepest ocean trenches.
accessory pigment One of the class of pigments (such as fucoxanthin, phycobilin, and xanthophyll) present in various photosynthetic plants and that assist in the absorption of light and the transfer of its energy to chlorophyll. Also called masking pigment.
Echinodermata The phylum of exclusively marine animals to which sea stars, brittle stars, sea urchins, and sea cucumbers belong.
backshore That part or zone of a beach profile that extends landward from the sloping foreshore to a point of either vegetation development or a change of physiography, e.g. a sea cliff or a dune field.
Alaska gyre A small Pacific Ocean subpolar surface current gyre that rotates counter-clockwise south of Alaska.
perigee The point in the orbit of a satellite where it is closest to the main body; opposite of apogee.
phytoplankton Plantlike, usually single-celled members of the plankton community.
beach The region of the shore where loose material, sand, mud, or pebble, are deposited between high- and low-water marks.
active transport The movement of molecules from a region of low concentration to a region of high concentration through a semipermeable membrane at the expense of energy.
abyssal plain Flat, cold, sediment-covered ocean floor between the continental rise and the mid-oceanic ridge at a depth of 3,700 to 5,300 meters. Abyssal plains are more extensive in the Atlantic and Indian Oceans than in the Pacific.
mesosphere The rigid inner mantle, similar in a chemical composition to the asthenosphere.
continental crust Solid, outer layers of earth, including the rocks of the continents
ocean basin Deep-ocean floor made of basaltic crust. Compare continental margin: The submerged outer edge of a continent, made of granitic crust. Includes the continental shelf and continental slope.
Roaring Forties Areas of ocean either side of the Equator between 40° and 50° N or S latitude, noted for high winds and rough seas.
mangrove Flowering shrubs and trees tolerant of seawater, found on low-lying tropical coasts and estuaries
high seas That part of the ocean past the exclusive economic zone, which is considered common property to be shared by the citizens of the world. About 60% of the ocean area.
Catalan Sea See Balearic Sea
cartilage A tough, elastic tissue that stiffens or supports.
algin A mucilaginous commercial product of multicellular marine algae. Widely used as a thickening and emulsifying agent.
clumped distribution Distribution of organisms within a community in small, patchy aggregations, or clumps; the most common distribution pattern.
biological resource A living animal or plant collected for human use. Also called a living resource.
phylum One of the major groups of the animal kingdom whose members share a similar body plan, level of complexity, and evolutionary history. (Plural: phyla) (The major groups of the plant kingdom are called divisions.)
brash ice A type of sea ice; accumulations of floating ice made up of fragments not more than 2 meters across; the wreckage of other forms of ice.
convergent evolution The evolution of similar characteristics in organisms of different ancestry; the body shape of a porpoise and a shark, for instance.
plate tectonics The theory that Earth's lithosphere is fractured into plates, which move relative to each other and are driven by convection currents in the mantle. Most volcanic and seismic activity occurs at plate margins.
breakwater An artificial structure of durable material that interrupts the progress of waves to shore. Harbors are often shielded by breakwater.
meander Turn or winding curve of a current.
wind-induced vertical circulation Vertical movement in surface water (upwelling or downwelling) caused by wind.
Balearic Sea One of the seas that comprise the western basin of the Mediterranean Sea which is sometimes called the Catalan Sea. It lies between The Iberian coast and the Balearic Islands (Ibiza, Mallorca, Menorca) in the northwestern Mediterranean.
Arthropoda The phylum of animals that includes shrimp, lobsters, krill, barnacles, and insects. The phylum Arthropoda is the world's most successful.
diffusion The movement--driven by heat-- of molecules from a region of high concentration to a region of low concentration.
scuba Self-Contained Underwater Breathing Apparatus.
longshore drift Movement of sediments parallel to shore, driven by wave energy.
barycenter Center of mass and center rotation of the Earth-moon system, 1,700 kilometers inside Earth.
Bransfield Strait A strait located between the northern tip of the Antarctica Peninsula and the South Shetland Islands. 120 km wide and extends 460 km from Clarence Island to Low Island.
deep scattering layer (DSL) A relatively dense aggregation of fishes, squid, and other mesopelagic organisms capable of reflecting a sonar pulse that resembles a false bottom in the ocean. Its position varies with the time of day.
bathymetry the measurement and charting of the spatial variation of the ocean depths.
beach berm The nearly horizontal portion of a beach formed by the deposition of sediment by receding waves. A beach may have more than one berm.
atom The smallest particle of an element that exhibits the characteristics of that element.
mesopelagic Oceanic zone from 200-1000m.
period See wave period: the time it takes for successive wave crests to pass a fixed point.
bloom The sudden increase in phytoplankton number, usually associated with season changes.
barrier layer the layer between the thermocline and the halocline
deep zone The zone of the ocean below the pycnocline, in which there is little additional change of density with increasing depth. Contains about 80% of the world's water.
Cape Verde Basin An ocean basin located at about 15°N off the west coast of Africa in the North Atlantic Ocean.
cetaceans The whales and dolphins.
covalent bond A chemical bond formed between two atoms by electron sharing.
entropy A measure of the disorder in a system.
carbonate compensation depth (CCD) Also known as the calcite compensation depth, is the depth at which the amount of calcium carbonate preserved falls below 20% of the total sediment. This is also commonly defined as the depth at which the amount of calcium carbonate produced by organisms skeletal material in the overlying water column is equal to the rate at which it is dissolved in the water. No calcium carbonate will be deposited below this depth.
entrainment Mixing of salt water into fresh water overlying salt water, as in an estuary.
vanishing tide A mixed tide of considerable inequality in the two highs or two lows so that the "high low" may become indistinguishable from the "low high". The result is a vanishing tide, where no significant difference is apparent.
physiographic map Portrayal of earth's features by perspective drawing.
delta The deposit of sediments found at a river mouth, sometimes triangular in shape (hence the name after the Greek letter).
benthos Organisms living on or in the ocean bottom.
physical resource Any resource that has resulted from the deposition, precipitation, or accumulation of a useful nonliving substance in the ocean or seabed. Also called a nonliving resource.
buoy Floating object to float due to the support of the fluid the body is in or on.
low tide The low-water position corresponding to a tidal trough.
diurnal Applies to a location that normally experiences one high water and one low water during a tidal day of 24 hours.
inverse estuary An ambayment, often located in arid climates, with high evaporating and little freshwater input. Circulation is seaward at depth and inward at the surface, opposite that of a typical estuary. Salinity is generally higher than average seawater salinities.
crustal plate A segment of Earth's surface. Continental plates are about 25 miles thick and oceanic plates 3.1 miles thick.
continental shelf Gradually sloping submerged extension of a continent composed of granitic rock overlain by sediments. Has features similar to the edge of the nearby continent.
Annelida The phylum of animals to which segmented worms belong.
aphotic zone The part of the ocean where no surface light can penetrate.
nonvascular Describing photosynthetic autotrophs without vessels for the transport of fluid. Examples are algae.
barrier reef A coral reef surrounding an island or lying parallel to the shore of a continent, separated from land by a deep lagoon. Coral debris islands may form along the reef.
ocean One of the five great bodies of seawater defined by continental margins, the equator, and other arbitrary divisions.
breaker Sea surface water wave that has become too steep to be stable and collapses.
crustaceans Invertebrates with jointed limbs and hard chalky shells, such as lobsters, crabs, and shrimp.
apogee The point in the orbit of a satellite farthest from the main body; opposite of perigee.
algae Collective term for nonvascular plants possessing chlorophyll and capable of photosynthesis. Simple plants found as single cells or as seaweeds.
Columbus, Christopher 1451-1506. Italian explorer in the service of Spain who discovered islands in the Caribbean in 1492. Although traditionally credited as the discoverer of America, he never actually sighted the North American continent.
caldera undersea feature; a collapsed or partially-collapsed seamount, commonly of annular shape.
greenhouse effect The warming of the lower layers of the atmosphere caused by the trapping of solar radiation by carbon dioxide and other gases.
ice age One of several periods (lasting several thousand years each) of low temperature during the last million years. Glaciers and polar ice were derived from ocean water, lowering sea levels at least 100 meters (328 feet).
plankton Drifting or weakly swimming organisms suspended in water. Their horizontal position is to a large extent dependent on the mass flow of water than on their own swimming efforts.
remote sensing The use of airborne or satellite sensors to map Earth's surface in space and time.
intertropical convergence zone (ITCZ) The equatorial area at which the trade winds converge. The ITCZ usually lies at or near the meteorological equator. Also called the doldrums.
deep scattering layer (DSL) A relatively dense aggregation of fishes, squid, and other mesopelagic organisms capable of reflecting a sonar pulse that resembles a false bottom in the ocean. Its position varies with the time of day.
Pinnipedia The carnivoran suborder that contains the seals, sea lions, and walruses.
base A substance that combines with a hydrogen ion (H+) in solution.
drift net Fine, vertically suspended net that may be 7 meters (25 feet) high and 80 kilometers (50 miles) long.
aquaculture The growing or farming of plants and animals in a water environment under controlled conditions. Compare mariculture.
convergent plate boundary A region where plates are pushing together and where a mountain range, island arc, and/or trench will eventually form. Often a site of much seismic and volcanic activity.
pelagic zone The realm of open water. See also benthic zone: the seabed.
red tide Red coloration, usually of coastal waters, caused by large quantities of microscopic organisms (generally dinoflagellates); some red tides result in mass fish kills, others contaminate shellfish, and still others produce no toxic effects.
subduction zone An area where one crustal plate is forced under another plate, giving rise to volcanic activity and earthquakes.
Bay of Bengal The northeastern arm of the Indian Ocean, located between India and Burma.
spoil Dredged material.
zooplankton Animal members of the plankton community.
barrier layer the layer between the thermocline and the halocline
transverse ridge Ridge running at nearly right angles to main or principal ridge.
ocean 1) The great body of saline water that covers 70.78% of the surface of Earth. 2) One of its primary subdivisions, bounded by continents, the equator, and other imaginary lines.
commensalism A symbiotic interaction between two species in which only one species benefits and neither is harmed.
Beaufort scale Scale of wind forces by range of velocity; scale of sea state created by winds of these velocities
classification A way of grouping objects according to some stated criteria.
holoplankton Permanent members of the plankton community. Examples are diatoms and copepods. Compare to meroplankton.
Canary Basin An ocean basin located to the west of the Canary Islands in the eastern North Atlantic Ocean.
rise Long, broad elevation that rises gently and generally smoothly from the sea floor.
bathypelagic zone The ocean between 656 and 13,120 feet deep; One of five vertical ecological zones into which the deep sea is sometimes divided. This is the zone starting from 100 to 700 m deep (coinciding with the upper limit of the psychrosphere) at the 10°C isotherm.
Bjerknes, Vilhelm (1862-1951) Pioneering Norwegian physicist and discoverer of the nature and formation of extratropical cyclones, which cause most mid-latitude weather.
frontal storm Precipitation and wind caused by the meeting of two air masses, associated with an extratropical cyclone. Generally, one air mass will slide over or under the other, and the resulting expansion of air will cause cooling and consequently, rain or snow.
continental slope The sloping transition between the granite of the continent and the basalt of the seabed. The true edge of a continent.
bay mouth bar An exposed sandbar attached to a headland adjacent to a bay and extending across the mouth of the bay.
group velocity Speed of advance of a wave train; for deep water waves, half the speed of individual waves within the group.
Plantae The kingdom to which multicellular vascular autotrophs belong.
polar ocean areas Zones to the south of the Antarctic Convergence and to the north of the Arctic Convergence.
El Niño A southward-flowing nutrient-poor current of warm water off the coast of western South America, caused by a breakdown of trade-wind circulation.
mohorovicic discontinuity (moho) Boundary between crust and mantle, marked by a rapid increase in seismic wave speed.
caldera undersea feature; a collapsed or partially-collapsed seamount, commonly of annular shape.
Cape Verde Basin An ocean basin located at about 15°N off the west coast of Africa in the North Atlantic Ocean.
partially mixed estuary An estuary in which an influx of seawater occurs beneath a surface layer of fresh water flowing seaward. Mixing occurs along the junction.
oxygen minimum zone A zone in which oxygen is depleted by animals and not replaced by phytoplankton.
buffer sublayer That part of a boundary layer where the viscous stress and the Reynolds stress have the same order of magnitude and the linear velocity profile turns smoothly into the logarithmic profile.
Caribbean Sea The largest marginal sea of the Atlantic Ocean, with a surface area twice that of the Mediterranean Sea.
algin A mucilaginous commercial product of multicellular marine algae. Widely used as a thickening and emulsifying agent.
Bering Sea A marginal sea located on the northern rim of the Pacific Ocean centered at approximately 58°N and 160°W. It is surrounded by Alaska to the east, Siberia to the west, and the Aleutian Island arc to the south.
rift zone A region where the lithosphere splits and separates allowing new crustal material to intrude into the crack or rift.
baleen The interleaved, hard, fibrous, hornlike filters within the mouth of baleen whales.
agar Substance produced by red algae; the gelatin-like product of these algae.
ebb current Water rushing out of an enclosed harbor or bay because of the fall in sea level as a tide trough approaches.
brash ice A type of sea ice; accumulations of floating ice made up of fragments not more than 2 meters across; the wreckage of other forms of ice.
meiobenthos Very small animals living buried in the sediments of the sea floor.
flushing time Length of time required for an estuary to exchange its water depth with the open ocean.
drag The resistance to movement of an organism induced by the fluid through which it swims.
oceanic crust The outermost solid surface of Earth beneath ocean floor sediments, composed primarily of basalt.
Cariaco Basin A 1400 m deep depression within the continental shelf of Venezuela.
Baguio The local name given to tropical cyclones in the Philippines, especially those occurring from July to November.
Coriolis, Gaspard Gustave de (1792-1843) The French scientist who in 1835 worked out the mathematics of the motion of bodies on a rotating surface. Refer to Coriolis effect.
angiosperm A flowering vascular plant that reproduces by means of a seed-bearing fruit. Examples are sea grasses and mangroves.
dispersion Separation of wind waves by wavelength (and therefore wave speed) as they move away from the fetch (the place of their formation). Dispersion occurs because waves with long wavelengths move more rapidly than waves with short wavelengths.
longitude Regularly spaced imaginary lines on Earth's surface running North and South and converging at the poles.
neritic Of the shore or coast. Refers to continental margins and the water covering them, or to nearshore organisms.
primary producer An organism capable of using energy from light or energy-rich chemicals in the environment to produce energy-rich organic compounds. An autotroph.
clockwise Rotation around a point in the direction that clock hands move.
Brazil Basin An ocean basin located off the eastern coast of Brazil in the west-central Atlantic Ocean.
angiosperm A flowering vascular plant that reproduces by means of a seed-bearing fruit. Examples are sea grasses and mangroves.
accessory pigment One of the class of pigments (such as fucoxanthin, phycobilin, and xanthophyll) present in various photosynthetic plants and that assist in the absorption of light and the transfer of its energy to chlorophyll. Also called masking pigment.
apogean tide A monthly tide of decreased range that occurs when the moon is farthest from earth (at apogee)
lateral-line system A system of sensors and nerves in the head and midbody of fishes and some amphibians that functions to detect low-frequency vibrations in water.
Baguio The local name given to tropical cyclones in the Philippines, especially those occurring from July to November.
longitude A measure of east-west location relative to the Prime Meridian that runs through the Greenwich Observatory, London, UK.
berm A nearly horizontal accumulation of sediment parallel to shore. Marks the normal limit of sand deposition by wave action.
hydrothermal vent A spring of superheated, mineral-rich water found on some ocean ridges.
alveoli A tiny thin-walled capillary rich sack in the lungs where the exchange of oxygen and carbon dioxide take place.
bond An energy relationship that holds two atoms together as a result of changes in their electron distribution.
physical factor An aspect of the physical environment that affects living organisms, such as light, salinity, or temperature.
pollutant A harmful substance or heat energy introduced into an ecosystem by human activities.
biomass The mass of living material in a given area or volume of habitat.
bioturbation Reworking of sediments by organisms that burrow into them and ingest them.
trade winds Steady winds blowing east to west toward the equator to replace hot air rising from the equatorial region.
paleoceanography The study of the ocean's past.
biological factor A biologically generated aspect of the environment, such as predation or metabolic waste products, that affects living organisms. Biological factors usually operate in association with purely physical factors such as light and temperature.
mid-ocean ridge A region of the ocean floor where magma rises to the surface to create new ocean floor on either side of a central rift valley.
Antarctic Circle The line of latitude at 66°33'S marking the northern limit of the Antarctic region. The imaginary line around the Earth, parallel to the equator at 66°33'S, marking the southernmost limit of sunlight at the June solstice. The Antarctic Circle marks the northern limit of the area within which, for one day or more each year, the sun does not sea (around December 21) or rise (around June 21).
Bivalvia The class of phylum Mollusca that includes clams, oysters, and mussels.
wind duration The length of time the wind blows over the ocean surface, a factor in wind wave development.
current Mass flow of water. (The term is usually reserved for horizontal movement.)
Coriolis, Gaspard Gustave de (1792-1843) The French scientist who in 1835 worked out the mathematics of the motion of bodies on a rotating surface. Refer to Coriolis effect.
Phaeophyta Brown multicellular algae, including kelps.
osmoregulation The regulation of the concentration of body fluids by aquatic animals.
dune An accumulation of wind-blown sand often found above the high-tide mark on sand shores. Also, a great book by Frank Herbert!
extremophile Microorganism that thrives under extreme conditions of temperature, lack of oxygen, or high acid or salt levels; these conditions kill most other organisms.
Blade Algal equivalent of a vascular plant's leaf. Also called a frond.
period See wave period: the time it takes for successive wave crests to pass a fixed point.
beta refraction An effect that results from the latitudinal variation of Rossby wave phase speed which is, in turn, due to the beta effect. If a line of Rossby waves were started along a straight eastern ocean boundary, then those at low latitudes would arrive at the western boundary before those at high latitudes.
alternation of generations A reproductive cycle in which a plant alternates between sexual and asexual stages.
buoy Floating object to float due to the support of the fluid the body is in or on.
poorly sorted sediment A sediment in which particles of many sizes are found.
plate tectonics The processes by which the plates that form Earth's surface are formed, moved, and destroyed.
amnesic shellfish poisoning Poisoning caused by demic acid secreted by a diatom. It has been known to kill birds and humans and obtains its name from the fact that the pervasive symptoms in humans is amnesia.
anoxic Deficient in oxygen.
authogenic sediment Sediment formed directly by precipitation from seawater. Also called hydrogenous sediment.
antinode Portion of a standing wave with maximum vertical motion.
caballing Mixing of two water masses of identical densities but different temperatures and salinities, such that the resulting mixture is denser than its components.
adiabatic Pertaining to a change in the temp of a mass resulting from compression or expansion; requires no addition of heat to or loss of heat from the substance.
mass extinction A catastrophic, global event in which major species perish abruptly.
Gulf Stream The strong western boundary current of the North Atlantic, off the Atlantic Coast of the United States.
scarp Elongated and comparatively steep slope separating flat or gently sloping areas on the sea floor or on a beach.
episodic wave Abnormally high wave unrelated to a local storm conditions.
compound A substance composed of two or more elements in a fixed proportion.
astrolabe An early navigation instrument that was the forerunner of the sextant.
Harrison, John (1693-1776) British clockmaker who invented the modern chronometer in 1760.
active transport The movement of molecules from a region of low concentration to a region of high concentration through a semipermeable membrane at the expense of energy.
core The innermost layer of the Earth, composed primarily of iron, with nickel and heavy elements. The inner core is thought to be a solid 6,000°C (11,000°F) sphere, the outer core a 5,000°C (9,000°F) liquid mass. The average density of the outer core is about 11.8 g/cm3, and that of the inner core is about 16 g/cm3.
polyp One of two body forms of Cnidaria. Polyps are cup shaped and possess rings of tentacles. Coral animals are polyps.
downwelling Circulation pattern in which surface water moves vertically downward.
continental slope The steeply inclined edge of a continental plate below the continental shelf.
acoustic profiling The use of seismic energy to measure sediment thickness and layering on the sea floor.
orbit In ocean waves, the circular pattern of water particle movement at the air-sea interface. Orbital motion contrasts with the side-to-side or back-and-forth motion of pure transverse or longitudinal waves.
bucket temperature The surface temperature of the ocean as measured by a bucket thermometer.
zenith Point in the sky that is immediately overhead.
parasitism A symbiotic relationship in which one species spends all or part of its life cycle on or within another, using the host species (or food within the host) as a source of nutrients. The most common form of symbiosis.
active sonar A device that generates underwater sound from special transducers and analyzes the returning echoes to gain information of geological, biological, or military importance.
biogenous sediment Sediment of biological origin. Organisms can deposit calcareous (calcium-containing) or siliceous (silicon-containing) residue.
sea stack Isolated mass of rock rising from the sea near a headland from which it has been separated by erosion.
active transport The movement of molecules from a region of low concentration to a region of high concentration through a semipermeable membrane at the expense of energy.
doldrums The zone of rising air near the equator known for sultry air and variable breezes. See also intertropical convergence zone (ITCZ).
accretion An increase in the mass of a body by accumulation or a clumping of smaller particles.
chronometer A very consistent clock. It doesn't need to tell accurate time, but its rate of gain or loss must be constant and known exactly so that accurate time may be calculated.
backwash Water returning to the ocean from waves washing onto a beach.
amnesic shellfish poisoning Poisoning caused by demic acid secreted by a diatom. It has been known to kill birds and humans and obtains its name from the fact that the pervasive symptoms in humans is amnesia.
hierarchy Grouping of objects by degrees of complexity, grade, or class. A hierarchical system of nomenclature is based on distinctions within groups and between groups.
chaetognaths Free-swimming, carnivorous, pelagic, wormlike, planktonic animals; arrowworms.
baroclinic Descriptive of an atmosphere or ocean in which surfaces of pressure and density intersect at some level or levels. The state of the real atmosphere and ocean, as opposed to barotropic.
Balearic Sea One of the seas that comprise the western basin of the Mediterranean Sea which is sometimes called the Catalan Sea. It lies between The Iberian coast and the Balearic Islands (Ibiza, Mallorca, Menorca) in the northwestern Mediterranean.
plate One of about a dozen rigid segments of Earth's lithosphere that move independently. The plate consists of continental or oceanic crust and the cool, rigid upper mantle directly below the crust.
lagoon A shallow body of seawater generally isolated from the ocean by a barrier island. Also, the body of water enclosed within an atoll, or the water within a reverse estuary.
cosmogenous sediment Sediment of extraterrestrial origin.
osmotic pressure Pressure that builds up in a confined fluid because of osmosis.
breaker zone The portion of the nearshore zone where waves arriving from offshore become unstable and break
bilateral symmetry Body structure having left and right sides that are approximate mirror images of each other. Examples are crabs and humans. Compare radial symmetry.
pelagic sediment Sediments of the slope, rise, and deep-ocean floor that originate in the ocean.
geographical equator 0° latitude, an imaginary line equidistant from the geographical poles.
hermatypic Describing coral species possessing symbiotic zooxanthellae within their tissues and capable of secreting calcium carbonate at a rate suitable for reef production.
internal wave A progressive wave occurring at the boundary between liquids of different densities.
Baltic Sea A dilution basin type of Mediterranean sea that is connected to and experiences limited, intermittent water exchange with the North Sea.
high water Maximum height reached by a rising tide.
abyssopelagic Oceanic zone from 4000m to the deepest depth.
authogenic sediment Sediment formed directly by precipitation from seawater. Also called hydrogenous sediment.
base A substance that combines with a hydrogen ion (H+) in solution.
granite The relatively light crustal rock -- composed mainly of oxygen, silicon, and aluminum -- that forms the continents. Its density is about 2.7 g/cm3.
deep-water wave A wave in water deeper than one-half its wavelength.
photic zone The thin film of lighted water at the top of the world ocean. The photic zone rarely extends deeper than 200 meters (660 feet). Compare euphotic zone: The upper layer of the photic zone in which net photosynthetic gain occurs. Part of the photic zone, which is the thin film of lighted water at the top of the world ocean.
cryptic coloration Camouflage. May be active (under control of the animal) or passive (an unalterable color or shape).
biogeochemical sediment Natural processes that recycle nutrients in various chemical forms from the nonliving environment to the living organisms and then back to the nonliving environment.
PCBs Polychlorinated biphenyls. Chlorinated hydrocarbons once widely used to cool and insulate electrical devices and to strengthen wood or concrete. PCBs may be responsible for the changes in and declining fertility of some marine mammals.
chronometer A watch or clock able to maintain its accuracy on long sea voyages.
transgenic Describing an organism that contains hereditary material from another organism incorporated into its genetic material.
bathymetry the measurement and charting of the spatial variation of the ocean depths.
polar wandering curve A plot of the apparent location earth's north magnetic pole as a function of geologic time.
westward intensification The increase in the speed of geostrophic currents as they pass along the western boundary of an ocean basin.
homeotherm Organism with a body temperature that varies only within narrow limits.
Polyplacophora The class of the phylum Mollusca that includes the chitons.
action plan for the human environment In 1972 this UN program established 12 worldwide environmental units and determined procedures for assessing and monitoring various sources of pollution.
clockwise Rotation around a point in the direction that clock hands move.
backshore That part or zone of a beach profile that extends landward from the sloping foreshore to a point of either vegetation development or a change of physiography, e.g. a sea cliff or a dune field.
convection cell Circulation in a fluid, or fluidlike material, caused by heating from below. Heating the base of a fluid lowers its density, causing it to rise. The rising fluid cools, becomes denser, and sinks, creating circulation.
clay Sediment particle smaller than 0.004mm in diameter; the smallest sediment size category.
Forchhammer's principle The proportions of major conservative elements in seawater remain nearly constant, though total salinity may change with location Also called the principle of constant proportions.
niche Description of an organism's functional role in a habitat. Its "job".
Bohol Sea A small sea centered in the Philippines at about 124°E and 9°S.
atom The smallest particle of an element that exhibits the characteristics of that element.
aquaculture The growing or farming of plants and animals in a water environment under controlled conditions. Compare mariculture.
disphotic zone The lower part of the photic zone, where there is insufficient light for photosynthesis.
greenhouse effect Trapping of heat in the atmosphere. Incoming short-wavelength solar radiation penetrates the atmosphere, but the outgoing longer-wavelength radiation is absorbed by greenhouse gases and reradiated to Earth, causing a rise in surface temperature.
Catalan Sea See Balearic Sea
bucket thermometer A thermometer with an insulated container around the bulb.
abyssal storm Storm-like occurrences of rapid current movement affecting the deep ocean floor. They are believed to be caused by warm- and cold-core eddies of surface currents.
capillary wave A tiny wave with a wavelength of less than 1.73 centimeters (0.68 inch), whose restoring force is surface tension; the first type of wave to form when the wind blows.
projection A system of projecting lines of latitude and longitude onto a plain surface to create a map with specific physical properties.
lithification Conversion of a sediment into sedimentary rock by pressure or by the introduction of a mineral cement.
Antarctic Bottom Water The densest ocean water (1.0279 g/cm3), formed primarily in Antarctica's Weddell Sea during Southern Hemisphere winters.
chart A map that depicts mostly water and the adjoining land areas.
perigee The point in the orbit of a satellite where it is closest to the main body; opposite of apogee.
attenuation Decrease in the energy of a wave or beam of particles occurring as the distance from the source increases; caused by absorption, scattering, and divergence from a point source.
fringing reef A reef attached to the shore of a continent or island.
continental rise The wedge of sediment forming the gentle transition from the outer (lower) edge of the continental slope to the abyssal plain. Usually associated with passive margins.
polar reversal The periodic reversal of earth's magnetic field where the north magnetic pole becomes the south magnetic pole and vice versa.
current Mass flow of water. (The term is usually reserved for horizontal movement.)
channel A body of water that connects two larger bodies of water. A channel is also part of a river or harbor that is deep enough to let ships sail through.
mixed tide A complex tidal cycle, usually with two high tides and two low tides of unequal height per day.
berm crest The top of the berm, the highest point on most beaches. Corresponds to the shoreward limit of wave action during most high tides.
borderland undersea feature; a region adjacent to a continent, normally occupied by or bordering a shelf and sometimes emerging as islands.
biological pump Photosynthetic transfer of carbon as CO2 from the atmosphere to the ocean in the form of organic molecules; carbon is transferred to intermediate and deep-ocean water when organic material sinks and decays.
air mass A large mass of air with nearly uniform temperature, humidity, and density throughout.
stratosphere The layer of the atmosphere above the troposphere where temperature is constant or increases with altitude.
atmospheric pressure Pressure, at any point on Earth, exerted by the atmosphere as a consequence of gravitational force exerted on the column of air lying directly above the point.
Antarctic Bottom Water The densest ocean water (1.0279 g/cm3), formed primarily in Antarctica's Weddell Sea during Southern Hemisphere winters.
oolite sand Hydrogenous sediment formed when calcium carbonate precipitates from warmed seawater as pH rises, forming rounded grains around a shell fragment or other particle.
basin An undersea feature; a depression, in the sea floor, more or less equidimensional in plan and of variable extent; large depression of the sea floor having about equal dimensions of length and width.
barrier reef One of three geomorphologically distinct types of coral reefs, the other two being fringing reefs and atolls. Barrier reefs are separated from land by a lagoon usually formed by coastal subsidence; A coral reef around islands or along continental coasts, with a deep lagoon between the reef and the coast.
reef flat Portion of a coral reef landward of the reef crest and seaward of the lagoon.
Arthropoda The phylum of animals that includes shrimp, lobsters, krill, barnacles, and insects. The phylum Arthropoda is the world's most successful.
biosynthesis The initial formation of life on Earth.
atoll A ring-shaped island of coral reefs and coral debris enclosing, or almost enclosing, a central shallow lagoon from which no land protrudes. Atolls often form over sinking, inactive volcanoes.
diurnal inequality Difference in height between two high waters or two low waters of each tidal day; the difference in speed between the two flood currents or two ebb currents of each tidal day.
shingles Flat, water-worn pebbles, or cobbles, found in beds along a beach.
Canary Basin An ocean basin located to the west of the Canary Islands in the eastern North Atlantic Ocean.
autotroph An organism that makes its own food by photosynthesis or chemosynthesis.
anoxic Deficient in oxygen.
frustule Siliceous external cell wall of a diatom consisting of two interlocking valves fitted together like the halves of a box.
marine science The process (or result) of applying scientific method to the ocean, its surroundings, and the life forms within it. Also called oceanography or oceanology.
Beaufort Sea The marginal sea consisting of the waters off the northern coast of Alaska and Canada.
Bali Sea A regional sea which is part of the Australasian Mediterranean Sea in the southwest Pacific Ocean. It is centered at around 116°E and 8.5°S and is bordered by Bali and Sumbawa to the south and Madura to the west.
biological pump Photosynthetic transfer of carbon as CO2 from the atmosphere to the ocean in the form of organic molecules; carbon is transferred to intermediate and deep-ocean water when organic material sinks and decays.
metabolic rate The rate at which energy-releasing reactions proceed within an organism.
test The shell of an organism.
atmospheric pressure Pressure, at any point on Earth, exerted by the atmosphere as a consequence of gravitational force exerted on the column of air lying directly above the point.
Global Positioning System (GPS) Satellite-based navigation system that provides a geographical position -- longitude and latitude -- accurate to less than 1 meter.
covalent bond A chemical bond formed between two atoms by electron sharing.
sea state Numerical or written description of the roughness of the ocean surface relative to wave height.
trophic web The complex feeding relationships between plants and animals in a habitat.
ionizing radiation Fast-moving particles or high-energy electromagnetic radiation emitted as unstable atomic nuclei disintegrate. The radiation has enough energy to dislodge one or more electrons from atoms it hits to form charged ions, which can react with and damage living tissue.
backshore Sand on the shoreward side of the berm crest, sloping away from the ocean.
hydrothermal vent Spring of hot, mineral- and gas-rich seawater found on some oceanic ridges in zones of seafloor spreading.
isopycnal Having a uniform density.
abyssopelagic Oceanic zone from 4000m to the deepest depth.
Arctic Ocean An ice-covered ocean north of the continents of North America and Eurasia.
lower mantle The rigid portion of Earth's mantle below the asthenosphere.
acoelomate Without a secondary body cavity (coelom).
echolocation The use of reflected sound to detect environmental objects. Cetaceans use echolocation to detect prey and avoid obstacles.
Antarctic Circumpolar Current The current driven by powerful westerly winds north of Antarctica. The largest of all ocean currents, it continues permanently eastward without changing direction.
phytoplankton Plantlike, usually single-celled members of the plankton community.
carbon cycle The cycling of carbon in the form of carbon dioxide, carbonates, organic compounds, etc. between various reservoirs, e.g. the atmosphere, the oceans, land and marine biota and, on geological time scales, sediments, and rocks.
plankton net Conical net of fine nylon or Dacron fabric used to collect plankton.
atmospheric pressure Pressure, at any point on Earth, exerted by the atmosphere as a consequence of gravitational force exerted on the column of air lying directly above the point.
polar cell The atmospheric circulation cell centered over each pole.
photosynthesis The process by which autotrophs bind light energy into the chemical bonds of food with the aid of chlorophyll and other substances. The process uses carbon dioxide and water as raw materials and yields glucose and oxygen.
Bay of Nice Located in the north western Mediterranean basin.
adiabatic Pertaining to a change in the temp of a mass resulting from compression or expansion; requires no addition of heat to or loss of heat from the substance.
biogeochemical sediment Natural processes that recycle nutrients in various chemical forms from the nonliving environment to the living organisms and then back to the nonliving environment.
Pacific Ring of Fire The zone of seismic and volcanic activity that encircles the Pacific Ocean.
current A flow of water in the sea, generated by wind, tidal movements, or thermohaline circulation.
infauna Animals that live buried in the sediment.
density stratification The formation of layers in a material, with each deeper layer being denser (weighing more per unit of volume) than the layer above.
ciguatera Toxin found in fish of tropical regions; produced by dinoflagellates.
Panthalassa Name given by Alfred Wegener to the ocean surrounding Pangaea.
Mollusca The phylum of animals that includes chitons, snails, clams, and octupuses.
Cnidaria The phylum of animals to which corals, jellyfish, and sea anemones belong.
community The populations of all species that occupy a particular habitat and interact within that habitat.
bank An undersea feature; and elevation of the sea floor, over which the depth of water is relatively shallow, but sufficient for safe surface navigation.
Greenwich Mean Theorem (GMT) Solar time along the prime meridian passing through Greenwich, England; also known as Universal Time or Zulu Time.
molecule A group of atoms held together by chemical bonds. The smallest unit of a compound that retains the characteristic of the compound.
bioluminescence Biologically produced light.
coastal upwelling Upwelling adjacent to a coast, usually induced by wind.
primary production The biological conversion of inorganic carbon (carbon dioxide) into living material (organic carbon)
hurricane An intense tropical cyclone w/ winds that move counterclockwise around a low-pressure system.
berm crest The top of the berm, the highest point on most beaches. Corresponds to the shoreward limit of wave action during most high tides.
front The boundary between two air masses of different density. The density differences can be caused by differences in temperature and/or humidity.
buoyancy The ability of an object to float in a fluid by displacement of a volume of fluid equal to it in mass.
capillary wave A wave on a fluid interface for which the restoring force is surface tension.
bulkhead Structure separating land and water areas; primarily designed to resist earth sliding and slumping or to reduce wave erosion at the base of a cliff.
dynamic theory of tides Model of tides that takes into account the effects of finite ocean depth, basin resonances, and the interference of continents on tide waves.
low-energy coast A coast only rarely exposed to large waves.
degree An arbitrary measure of temperature. One degree Celsius (°C) equals 1.8 degrees Fahrenheit (°F).
eutrophication A set of chemical, physical, and biological changes brought about when excessive nutrients are released into water.
acoustic thermometry of ocean climate ATOC; the measurement of ocean-wide changes in water properties such as temperature by transmitting and receiving low frequency sound signals.
euryhaline Describing an organism able to tolerate a wide range of salinity.
Brazil Basin An ocean basin located off the eastern coast of Brazil in the west-central Atlantic Ocean.
aseimic ridge see transverse ridge
ROV A Remotely Operated Vehicle- unmanned submersible controlled and powered from the surface by an umbilical cord.
shoal Elevation of the sea bottom comprising any material except rock or coral (in which case it is a reef); may endanger surface navigation.
kingdom The largest category of biological classification. Five kingdoms are presently recognized.
acoelomate Without a secondary body cavity (coelom).
littoral zone The band of coast alternately covered and uncovered by tidal action; the intertidal zone.
berm A horizontal ridge of sand or shingle running parallel to the shore, at the limit of wave action.
Antarctic Circle The line of latitude at 66°33'S marking the northern limit of the Antarctic region. The imaginary line around the Earth, parallel to the equator at 66°33'S, marking the southernmost limit of sunlight at the June solstice. The Antarctic Circle marks the northern limit of the area within which, for one day or more each year, the sun does not sea (around December 21) or rise (around June 21).
crest Highest part of a progressive wave above average water level.
base A substance that combines with a hydrogen ion (H+) in solution.
specific gravity Ratio of the density of a substance to the density of 4C water.
Porifera The phylum of animals to which sponges belong.
chronometer A very consistent clock. It doesn't need to tell accurate time, but its rate of gain or loss must be constant and known exactly so that accurate time may be calculated.
central water A term used to identify thermocline water masses in all three oceans. The water arrives at a thermocline via a process known as subduction.
big bang The hypothetical event that started the expansion of the universe from a geometric point. The beginning of time.
motile Able to move about.
andesite A volcanic rock intermediate in composition between basalt and granite; associated with subduction zones.
bioluminescence The generation of light by living organisms using the enzyme luciferase.
catastrophism The theory that the Earth's surface features are formed by catastrophic forces such as the biblical flood. Catastrophists believe in a young Earth and a literal interpretation of the biblical account of Creation.
cabbeling A phenomenon that occurs when two water masses with identical densities but different temperatures and salinities mix to form a third water mass with a greater density than either of its constituents.
isopleth Line of equal density
isostasy Mechanism by which areas of earth's crust rise or subside until their masses are in balance, "floating" on the mantle.
lunar month Time required for the moon to pass from one new moon to another new moon (approx. 29 days)
Meteor Expedition German Atlantic expedition begun in 1925; the first to use an echo sounder and other modern electrical and electronic instrumentation.
bloom High concentration of phytoplankton in an area, caused by increased reproduction; often produces discoloration of water. See red tide.
Antarctic Convergence Convergence zone encircling Antarctica between about 50° and 60°S, marking the boundary between Antarctic Circumpolar Water and Subantarctic Surface Water.
barrier reef One of three geomorphologically distinct types of coral reefs, the other two being fringing reefs and atolls. Barrier reefs are separated from land by a lagoon usually formed by coastal subsidence; A coral reef around islands or along continental coasts, with a deep lagoon between the reef and the coast.
acid A substance that releases a hydrogen ion (H+) in solution.
graben A portion of earth's crust that has moved downward and is bounded by steep faults; a rift.
earthquake A sudden motion of Earth's crust resulting from waves in Earth caused by faulting of the rocks or by volcanic activity.
ozone layer A diffuse layer of ozone mixed with other gases surrounding the world at a height of about 20 to 40 kilometers (12 to 25 miles).
piston corer A seabed-sampling device capable of punching through up to 25 meters (80 feet) of sediment and returning an intact plug of material.
chlorinity A measure of the amount of chlorine or other halides in water (especially seawater).
breakwater An artificial structure of durable material that interrupts the progress of waves to shore. Harbors are often shielded by breakwater.
chiton A polyplasophoran mollusk.
pack ice Sea ice that forms around the permanent ice sheets of polar regions in winter and which thins and retreats in the summer.
deep zone The zone of the ocean below the pycnocline, in which there is little additional change of density with increasing depth. Contains about 80% of the world's water.
oceanic ridge Young seabed at the active spreading center of an ocean, often unmasked by sediment, bulging above the abyssal plain. The boundary between diverging plates. Often called a mid-ocean ridge, though less than 60% of the length exists at mid-ocean.
atmospheric circulation cell Large circuit of air driven by uneven solar heating and the Coriolis effect. Three circulation cells form in each hemisphere. See also Ferrel cell; Hadley cell; polar cell.
heat capacity The heat, measured in calories, required to raise 1 gram of substance 1 degree Celsius. The input of 1 calorie of heat energy raises the temperature of 1 gram of pure water by 1 degree.
zooxanthellae Unicellular dinoflagellates that are symbiotic with coral and produce the relatively high pH and some of the enzymes essential for rapid calcium-carbonate deposition in coral reefs.
pelagic zone The water column.
oxygen revolution The time span, from about 2 billion to 400 million years ago, during which photosynthetic autotrophs changed the composition of Earth's atmosphere to its current oxygen-rich mixture.
Animalia The kingdom to which multicellular heterotrophs belong.
insolation rate The amount of solar energy reaching Earth's surface per unit of time.
population density The number of individuals per unit area.
by-catch See incidental catch.
CFCs A class of halogenated hydrocarbons thought to be depleting Earth's atmospheric ozone. CFCs are used as cleaning agents, refrigerants, fire extinguishing fluids, spray can propellants, and insulating foams.
pH scale A measure of the acidity or alkalinity of a solution. Numerically, the negative logarithm of the concentration of hydrogen ions in an aqueous solution. A pH of 7 is neutral; lower numbers indicate acidity, and higher numbers indicate alkalinity.
polar ocean areas Zones to the south of the Antarctic Convergence and to the north of the Arctic Convergence.
phycobilin A reddish accessory pigment found in red algae.
Crustacea The class of phylum Arthropoda to which lobsters, shrimp, barnacles, crabs, and copepods belong.
ectotherm An organism incapable of generating and maintaining steady internal temperature from metabolic heat and therefore whose internal body temperature is approximately the same as that of the surrounding environment. A cold-blooded organism.
knot A speed of 1 nautical mile per hour. See also nautical mile: the length of 1 minute of latitude, 6,076 feet, 1.15 statute miles, or 1.85 kilometers..
solar constant Rate at which solar radiation is received on a unit surface that is perpendicular to the direction of incident radiation just outside earth's atmosphere at earth's mean distance from the sun; equal to be 2 cal/cm2/min.
environmental resistance All of the limiting factors that act together to regulate the maximum allowable size, or carrying capacity, of a population.
carrying capacity The size at which a particular population in a particular environment will stabilize when its supply of resources--including nutrients, energy and living space -- remains constant.
falling tide tide period between high and low water. Also known as ebb tide.
littoral zone Seashore between high and low tide.
high tide The maximum elevation reached by each rising tide.
countercurrent A surface current flowing in the opposite direction from an adjacent surface current.
syzygy Occurs twice a month, when the sun and moon are in conjunction (lined up on the same side of earth at the new moon) and when they are in opposition (on opposite sides of earth at the full moon, though usually not so directly in line as to produce and eclipse). In either case, the gravitational effects of the sun and the moon reinforce each other, and tidal range is increased.
ice pack A large, floating expanse of broken ice masses pressed and frozen together.
buffer A group of substances that tends to resist change in the pH of a solution by combining with free ions.
Osteichthyes The class of fishes with bony skeletons.
barrier island A long, narrow, wave-built island lying parallel to the mainland and separated from it by a lagoon or bay. Compare sea island.
meridian Circle of longitude passing through the poles and any given point on earth's surface.
borderland undersea feature; a region adjacent to a continent, normally occupied by or bordering a shelf and sometimes emerging as islands.
diatom Earth's most abundant, successful, and efficient single-celled phytoplankton. Diatoms possess two interlocking valves made primarily of silica. The valves contribute to biogenous sediments.
Gulf Stream The strong western boundary current flowing the east coast of North America.
secchi disk White or white and black disk used to measure the transparency of the water by observing the depth at which the disk disappears from view.
population A group of individuals of the same species occupying the same area.
Ferrel cell The middle atmospheric circulation cell in each hemisphere. Air in these cells rises at 60° latitude and falls at 30° latitude. See also westerlies.
Jason-1 A follow-on satellite mission to TOPEX/Poseidon.
Chondrichthyes The class of fishes with cartilagenous skeletons: the sharks, skates, rays, and chimaeras.
anaerobic Living or functioning in the absence of oxygen.
multicellular Consisting of more than one cell.
equatorial upwelling Upwelling in which water moving westward on either side of the geographical equator tends to be deflected slightly poleward and replaced by deep water often rich in nutrients. See also upwelling.
node The line or point of no wave action in a standing pattern. See also amphidromic point: A "no-tide" point in an ocean caused by basin resonances, friction, and other factors around which tide crests rotate. About a dozen amphidromic points exist in the world ocean.
Cenderawasih Bay A bay on the northern coast of Irian Jaya centered at approximately 135°E and 2.5°S at the southwestern edge of the Pacific Ocean.
cabbeling A phenomenon that occurs when two water masses with identical densities but different temperatures and salinities mix to form a third water mass with a greater density than either of its constituents.
acoelomate Without a secondary body cavity (coelom).
algin A mucilaginous commercial product of multicellular marine algae. Widely used as a thickening and emulsifying agent.
nuclear energy Energy released when atomic nuclei undergo a nuclear reaction such as the spontaneous emission of radioactivity, nuclear fission, or nuclear fusion. About 17% of the electrical power generated in the United States is provided by the nuclear fission of uranium in civilian power reactors.
onshore Direction toward the shore.
continental crust The solid masses of the continents, composed primarily of granite.
bathybius Thomas Henry Huxley's name for an artifact of marine specimen preservation he thought was a remnant of the "primeval living slime."
asthenosphere The hot, plastic layer of the upper mantle below the lithosphere, extending some 350 to 650 kilometers below the surface. Convection currents within the asthenosphere power plate tectonics.
maximum sustainable yield The maximum amount of fish, crustaceans, and mollusks that can be caught without impairing future populations.
bay A recess in the shore or an inlet of a sea between two capes or headlands, not as large as a gulf but larger than a cove.
Harmful Algal Bloom (HAB) See red tide.
water budget Balance between the rates of water added and lost in an area.
bar Offshore ridge or mound of sand, gravel, or other loose material that is submerged, at least at high tide; located especially at the mouth of a river or estuary or lying a short distance from and parallel to the beach; A submerged or emerged mound of sand, gravel, or shell material built on the ocean floor in shallow water by waves and currents.
natural system of classification A method of classifying an organism based on its ancestry or origin.
experiments tests that simplify observation in nature or in the laboratory by manipulating or controlling the conditions under which observations are made.
barotropic Descriptive of a hypothetical atmosphere or ocean in which surfaces of pressure (isobaric surfaces) and density (isentropic surfaces) coincide at all levels, as compared to baroclinic. In a state of barotropic stratification, no potential energy is available for conversion to kinetic energy.
Cape Basin An ocean basin located to the west of South Africa at about 35°S in the South Atlantic Ocean.
ATP Adenosine triphosphate, the compound that acts as the immediate source of energy for all life on Earth. The energy stored in ATP is provided directly by photosynthesis or by respiration of glucose.
neritic sediment Continental shelf sediment consisting primarily of terrigenous material.
autotroph An organism that makes its own food by photosynthesis or chemosynthesis.
buffer factor Defined as the fractional changed in atmospheric CO2 divided by the fractional change in oceanic DIC after equilibrium has been reached.
Laurasia An ancient landmass that fragmented to produce North America and Eurasia.
bykill Animals unintentionally killed when desirable organisms are collected.
mixing time The time necessary to mix a substance through the ocean, about 1,600 years.
colligative properties Those characteristics of a solution that differ from those of pure water because of material held in solution.
benthic zone The seabed.
surimi Refined fish protein that is used to form artificial crab, shrimp, and scallop meat.
substrate Material making up the base on which an organism lives or to which it is attached.
cilia Microscopic, hairlike projections of living cells that beat in coordinated fashion and produce movement.
element A substance composed of identical atoms that cannot be broken into simpler substances by chemical means.
clamshell sampler Sampling device used to take shallow samples of the ocean bottom.
latitude Regularly spaced imaginary lines on Earth's surface running parallel to the equator.
artificial system of classification A method of classifying an object based on attributes other than its reason for existence, its ancestry, or its origin. Compare natural system of classification.
crust The outermost solid layer of Earth, composed mostly of granite and basalt; the top layer of the lithosphere. The crust has a density of 2.7-2.9 g/cm3 and accounts for 0.4% of Earth's mass.
acoustic thermometry of ocean climate ATOC; the measurement of ocean-wide changes in water properties such as temperature by transmitting and receiving low frequency sound signals.
benthic zone The seabed.
breaker Sea surface water wave that has become too steep to be stable and collapses.
breaker zone The portion of the nearshore zone where waves arriving from offshore become unstable and break
Hadley, George (1685-1768) A London lawyer and philosopher who worked out the overall scheme of wind circulation in an effort to explain the trade winds.
low tide The minimum elevation reached by each falling tide.
alternation of generations A reproductive cycle in which a plant alternates between sexual and asexual stages.
bathyal zone The marine ecologic zone that lies deeper than the continental shelf but shallower than the deep ocean floor, i.e. those depths corresponding to the locations of the continental slope and rise.
fucoxanthin A brown or tan accessory pigment found in many species of brown algae and some species of diatoms.
Eratosthenes of Cyrene (276-192 BC) Greek scholar and librarian at Alexandria who first calculated the circumference of the Earth about 230 BC.
buoyancy The ability of an object to float in a fluid by displacement of a volume of fluid equal to it in mass.
Bay of Nice Located in the north western Mediterranean basin.
caballing Mixing of two water masses of identical densities but different temperatures and salinities, such that the resulting mixture is denser than its components.
conduction The transfer of heat through matter by the collision of one atom with another.
alternation of generations A reproductive cycle in which a plant alternates between sexual and asexual stages.
cohesion Attachment of water molecules to each other by hydrogen bonds.
beta refraction An effect that results from the latitudinal variation of Rossby wave phase speed which is, in turn, due to the beta effect. If a line of Rossby waves were started along a straight eastern ocean boundary, then those at low latitudes would arrive at the western boundary before those at high latitudes.
surface zone The upper layer of ocean in which temperature and salinity are relatively constant with depth. Depending on local conditions, the surface zone may reach to 1,000 meters (3,300 feet) or be absent entirely. Also called the mixed layer.
jet stream (polar) A stream of air, between 30 and 50° N and S and about 12 km above earth, moving from west to east at an average speed of 1 km/h.
holdfast The multi-branched structure anchoring seaweeds to hard surfaces.
commercial extinction Depletion of a resource species to a point where it is no longer profitable to harvest the species.
action plan for the human environment In 1972 this UN program established 12 worldwide environmental units and determined procedures for assessing and monitoring various sources of pollution.
beach A zone of unconsolidated (loose) particles extending from below water level to the edge of the coastal zone.
Algulhas Current A warm current that carries Indian Ocean water around the southern tip of Africa and into the Atlantic Ocean.
isothermal Having a uniform temperature.
potable water Water suitable for drinking.
chemical bond An energy relationship that holds two atoms together as a result of changes in their electron distribution.
microtektite Translucent oblong particles of glass, a component of cosmogenous sediment.
jellyfish (sea jelly) semitransparent, bell-shaped pelagic organism, often with long tentacles bearing stinging cells.
Fissipedia The carnivoran suborder that includes sea otters.
Beaufort Sea The marginal sea consisting of the waters off the northern coast of Alaska and Canada.
Cook, James (1728-1779) Officer in the British Royal Navy who led the first European voyages of scientific discovery.
biological amplification Increase in concentration of certain fat-soluble chemicals such as DDT or heavy metal compounds, in successively higher trophic levels within a food web.
community The populations of all species that occupy a particular habitat and interact within that habitat.
Annelida The phylum of animals to which segmented worms belong.
beach The region of the shore where loose material, sand, mud, or pebble, are deposited between high- and low-water marks.
consumer A heterotrophic organism.
artificial system of classification A method of classifying an object based on attributes other than its reason for existence, its ancestry, or its origin. Compare natural system of classification.
biodegradable Able to be broken by natural processes into simpler compounds.
plate tectonics The theory that Earth's lithosphere is fractured into plates, which move relative to each other and are driven by convection currents in the mantle. Most volcanic and seismic activity occurs at plate margins.
acid rain Rain containing acids and acid-forming compounds such as sulfur dioxide and oxides of nitrogen.
Pangaea Name given by Alfred Wegener to the original "protocontinent". The breakup of Pangaea gave rise to the Atlantic Ocean and to the continents we see today.
hot spot A surface expression of a plume of magma rising from a stationary source of heat in the mantle.
drift sector See coastal circulation cell.
Bering Sea A marginal sea located on the northern rim of the Pacific Ocean centered at approximately 58°N and 160°W. It is surrounded by Alaska to the east, Siberia to the west, and the Aleutian Island arc to the south.
horse latitudes Zones of erratic horizontal surface air circulation near 30°N and 30°S latitudes. Over land, dry air falling from high altitudes produces deserts at these latitudes (for example, the Sahara).
bioturbation The stirring of sediment by animal life.
Gondwanaland An ancient landmass that fragmented to produce Africa, South America, Antarctica, Australia, and India.
bias The amount by which the average of a set of values departs from a reference value.
bathybius Thomas Henry Huxley's name for an artifact of marine specimen preservation he thought was a remnant of the "primeval living slime."
berm A horizontal ridge of sand or shingle running parallel to the shore, at the limit of wave action.
isohaline Having a uniform salt content.
centrifugal force Outward-directed force acting on a body moving along a curved path or rotating about an axis; an inertial force.
polar front Boundary between the polar cell and the Ferrell cell in each hemisphere.
microbial loop Component of marine food webs in which dissolved organic material cycles through bacteria and nanoplankton then back to small members of the zooplankton.
borderland undersea feature; a region adjacent to a continent, normally occupied by or bordering a shelf and sometimes emerging as islands.
chitin A complex nitrogen-rich carbohydrate from which parts of arthropod exoskeletons are constructed.
dredge Cyllindric or boxlike sampling device made of metal, net, or both, that is dragged across the bottom to obtain biological or geological samples.
fouling Attachment or growth of marine organisms on underwater objects, usually objects that are made or introduced by humans.
climax community A stable, long-established community of self-perpetuating organisms that tends not to change with time.
incidental catch The portion of any catch or harvest taken in addition to the targeted species.
current A flow of water in the sea, generated by wind, tidal movements, or thermohaline circulation.
amphidromic point A "no-tide" point in an ocean caused by basin resonances, friction, and other factors around which tide crests rotate. About a dozen amphidromic points exist in the world ocean. Also sometimes called a node.
mass A measure of the quantity of matter.
autotroph An organism that makes its own food by photosynthesis or chemosynthesis.
flagellum A whiplike structure used by some small organisms and gametes to move through the environment. (Plural, flagella.)
seamount A steep-sided circular or elliptical projection from the seafloor that is more than ⅔ mile in height.
density The mass per unit volume of a substance, usually expressed in grams per cubic centimeter (g/cm3); the mass of a substance for a given volume.
antinode Portion of a standing wave with maximum vertical motion.
benthic Descriptive of organisms that are attached to or resting on bottom sediments, as opposed to pelagic.
aphelion The point in the orbit of a satellite where it is farthest from the sun; opposite of perihelion.
eurythermal zone The upper layer of water, where temperature changes with the seasons.
calcareous ooze Partially composed organic matter mixed with a quantity of calcareous material on the bottom of some bodies of water; a fine-grained, deep-sea deposit of pelagic origin containing more than 30% calcium carbonate derived from the skeletal material of various plankton. It is the most extensive deposit on the ocean floor but restricted to depths less than about 3500 m due to the carbon compensation depth.
tsunami A huge wave created by earthquake or volcanic explosion. Mistakenly called a tidal wave.
basin An undersea feature; a depression, in the sea floor, more or less equidimensional in plan and of variable extent; large depression of the sea floor having about equal dimensions of length and width.
longshore current A current running parallel to shore in the surf zone, caused by the incomplete refraction of waves approaching the beach at an angle.
fast ice Sea ice that is anchored to shore or the sea floor in shallow water.
geostrophic flow Horizontal flow of water occurring when there is a balance between gravitation forces and the coriolis effect.
angle of incidence In meteorology, the angle of the sun above the horizon.
biodiversity The variety of different species within a habitat.
abyssal clay lithogenous sediment on the deep-sea floor composed of at least 70% clay-sized particles by weight.
spicules Small calcareous or siliceous skeletal structures found in sponges.
mean lower low water The arithmetic mean of the lesser of a daily pair of low waters, observed over a specific 19 year cycle called the national tidal datum epoch.
Camotes Sea A small sea within the Visayan Islands that comprise the middle portion of the Philippines.
Arctic Ocean An ice-covered ocean north of the continents of North America and Eurasia.
bay A recess in the shore or an inlet of a sea between two capes or headlands, not as large as a gulf but larger than a cove.
Bjerknes, Vilhelm (1862-1951) Pioneering Norwegian physicist and discoverer of the nature and formation of extratropical cyclones, which cause most mid-latitude weather.
spring tide A tide that occurs at or near the time of a new or full moon with a large tidal rise and fall.
armored beach A beach that is protected from wave and water erosion by coarse-size lag deposits.
calorie The amount of heat needed to raise the temperatures of 1 gram (0.035 ounce) of pure water by 1°C (1.8°F).
abyssal zone The ocean between 13,120 and 19,680 feet deep.
mitigation Coastal management concept requiring developers to replace developed areas with equivalent natural areas or to reengineer other areas to resemble areas prior to development.
mixture A close intermingling of different substances that still retain separate identities. The properties of a mixture are heterogenous; they may vary within the mixture.
Wilson, John Tuzo (1908-1993) Canadian geophysicist who proposed the theory of plate tectonics in 1965.
planet A smaller, usually nonluminous body orbiting a star.
Cnidaria The phylum of animals to which corals, jellyfish, and sea anemones belong.
dependency A feeding relationship in which an organism is limited to feeding on one species or, in extreme cases, on one size phase of one species.
acid rain Rain containing acids and acid-forming compounds such as sulfur dioxide and oxides of nitrogen.
aquaculture The growing or farming of plants and animals in a water environment under controlled conditions. Compare mariculture.
adsorption Attraction of ions to a solid surface.
hypertonic Referring to a solution having a higher concentration of dissolved substances than the solution that surrounds it. Opposite of hypotonic.
active sonar A device that generates underwater sound from special transducers and analyzes the returning echoes to gain information of geological, biological, or military importance.
ahermatypic Describing coral species lacking symbiotic zooxanthellae and incapable of secreting calcium carbonate at a rate suitable for reef production.
carbon dioxide The most important of the greenhouse gases with an atmospheric concentration of 353 ppm.
by-catch See incidental catch.
carbon-14 dating A radioisotope dating method wherein a radioactive isotope of carbon, also called radiocarbon, is used to date materials containing carbon.
benthos Organisms living on or in the ocean bottom.
convection cell Movement within a fluid resulting from differential heating and cooling of the fluid. Convection produces mass transport or mixing of the fluid.
Celebes Sea Alternate name for the Sulawesi Sea.
apogean tide A monthly tide of decreased range that occurs when the moon is farthest from earth (at apogee)
benthic Descriptive of organisms that are attached to or resting on bottom sediments, as opposed to pelagic.
declinational tide See diurnal tide
Phaeophyta Brown multicellular algae, including kelps.
salt marsh A relatively shallow coastal environment populated with salt-tolerant grasses. They are often found in temperate climates. They are extremely productive biologically and extend the shoreline seaward by trapping fine sediment.
nodule Solid mass of hydrogenous sediment, most commonly manganese or ferromanganese nodules and phosphorite nodules.
endotherm An organism capable of generating and regulating metabolic heat to maintain a steady internal temperature. Birds and mammals are the only animals capable of true endothermy. A warm-blooded organism.
declinational tide See diurnal tide
Holothuroidea The class of phylum Echinodermata to which sea cucumbers belong.
lee Shelter; the part or side sheltered from wind or waves.
buffer sublayer That part of a boundary layer where the viscous stress and the Reynolds stress have the same order of magnitude and the linear velocity profile turns smoothly into the logarithmic profile.
Antarctic Ocean An ocean in the Southern Hemisphere bounded to the north by the Atlantic Convergence and to the south by Antarctica.
evapotranspiration The combined effect of evaporation and transpiration.
commensalism A symbiotic interaction between two species in which only one species benefits and neither is harmed.
plate One of about a dozen rigid segments of Earth's lithosphere that move independently. The plate consists of continental or oceanic crust and the cool, rigid upper mantle directly below the crust.
red clay Red to brown fine-grained lithogenous deposit, of predominantly clay size, which is derived from land, transported by winds and currents, and deposited far from land and at a great depth; also known as brown mud or brown clay.
pelagic Of the open ocean. Refers to the water above the deep-ocean basins, sediments of oceanic origin, or organisms of the open ocean.
benthic Descriptive of organisms that are attached to or resting on bottom sediments, as opposed to pelagic.
orbital inclination The 23°27´ "tilt" of Earth's rotational axis relative to the plane of its orbit around the sun.
erosion A process of being gradually worn away.
Gastropoda The class of phylum Mollusca that includes snails and sea slugs.
Southern Oscillation Southern Oscillation is a reversal of airflow between normally low atmospheric pressure over the western Pacific and normally high pressure over the Eastern Pacific. The cause of El Niño.
EEZ exclusive economic zone: The offshore zone claimed by signatories to the 1982 United Nations Draft Convention of the Law of the Sea. The EEZ extends 200 nautical miles (370 kilometers) from a contiguous shoreline. See also United States Exclusive Economic Zone.
cold seep Cold seawater, rich in methane, hydrogen sulfide, and hydrocarbons issuing from the seafloor.
demersal fish Fish living near and on the bottom.
strait Narrow channel of water that connects two larger bodies of water, and thus lies between two landmasses.
membrane A complex structure of proteins and lipids that forms boundaries around and within the cell. It is usually semipermeable, allowing some kinds of molecules to pass through but not others.
flood current Water rushing into an enclosed harbor or bay because of the rise in sea level as a tide crest approaches.
oceanography The science of the ocean. See also marine science: The process (or result) of applying scientific method to the ocean, its surroundings, and the life forms within it.
piston corer A seabed-sampling device capable of punching through up to 25 meters (80 feet) of sediment and returning an intact plug of material.
biogenic One of three major components of deep sea sediments, the other two being authigenic and detrital. Biogenic sediment consists mainly of calcite and opal produced as the hard parts of organisms and eventually precipitated.
cohesion Attachment of water molecules to each other by hydrogen bonds.
gill membrane The thin boundary of living cells separating blood from water in a fish's (or other aquatic animal's) gills.
cartographer A person who makes maps and charts.
plate tectonics The processes by which the plates that form Earth's surface are formed, moved, and destroyed.
PCBs Polychlorinated biphenyls. Chlorinated hydrocarbons once widely used to cool and insulate electrical devices and to strengthen wood or concrete. PCBs may be responsible for the changes in and declining fertility of some marine mammals.
chlorophyll A pigment responsible for trapping sunlight and transferring its energy to electrons, thus initiating photosynthesis.
T-S diagram Graph of temperature verses salinity on which seawater samples taken at various depths are used to describe a water mass.
fringing reef A coral reef that forms around the shore of an island and gradually extends out to sea.
nebula Diffuse cloud of dust and gas.
guyot A flat-topped, submerged inactive volcano.
buffer factor Defined as the fractional changed in atmospheric CO2 divided by the fractional change in oceanic DIC after equilibrium has been reached.
molt To shed an external covering.
flood tide The period of tide between low water and high water. Also known as a rising tide.
deep-water wave A wave in water deeper than one-half its wavelength.
apogean tide A monthly tide of decreased range that occurs when the moon is farthest from earth (at apogee)
breaker Sea surface water wave that has become too steep to be stable and collapses.
barrier reef One of three geomorphologically distinct types of coral reefs, the other two being fringing reefs and atolls. Barrier reefs are separated from land by a lagoon usually formed by coastal subsidence; A coral reef around islands or along continental coasts, with a deep lagoon between the reef and the coast.
bathyal zone The ocean between about 200 and 4,000 meters deep.
semidiurnal Having a period of half a tidal day. East coast tides, for example, are semidiurnal, with two highs and two lows in approximately 24 hours.
polyculture Cultivation of more than one species of organism in an aquaculture system.
Celtic Sea A shallow embayment of the eastern North Atlantic bounded by Southern Ireland. Separated from the Irish Sea by a line drawn from Ramsey Island to Carnsore Point and from the English Channel by a line drawn from Ushant to Lands End.
sea A division of an ocean or a large body of saltwater partially enclosed by land. The term is also used for large, usually saline, lakes that lack a natural outlet.
plankton Drifting or weakly swimming organisms suspended in water. Their horizontal position is to a large extent dependent on the mass flow of water than on their own swimming efforts.
berm A nearly horizontal accumulation of sediment parallel to shore. Marks the normal limit of sand deposition by wave action.
eustatic change Global change in sea level that affects all the world's coastlines.
beach A zone of unconsolidated (loose) particles extending from below water level to the edge of the coastal zone.
pollutant A substance that causes damage by interfering directly or indirectly with an organism's biological processes.
Henry the Navigator (1394-1460) Prince of Portugal who established a school for the study of geography, seamanship, shipbuilding, and navigation.
compensation depth The depth in the water column at which the production of carbohydrates and oxygen by photosynthesis exactly equals the consumption of carbohydrates and oxygen by respiration. The break-even point for autotrophs. Generally a function of light level.
convergent evolution The evolution of similar characteristics in organisms of different ancestry; the body shape of a porpoise and a shark, for instance.
trailing margin (passing margin) The continental margin closest to the mid-ocean ridge.
density The mass per unit volume of a substance, usually expressed in grams per cubic centimeter (g/cm3); the mass of a substance for a given volume.
bathymetry The discovery and study of submerged contours.
escarpment Nearly continuous line of cliffs or steep slopes caused by erosion or faulting.
pressure Force per unit area.
semipermeable membrane Membrane that allows some substances to pass through but restricts or prevents the passage of other substances.
euphotic zone The upper layer of the photic zone in which net photosynthetic gain occurs. Part of the photic zone, which is the thin film of lighted water at the top of the world ocean. The photic zone rarely extends deeper than 200 meters (660 feet).
acoustic profiling The use of seismic energy to measure sediment thickness and layering on the sea floor.
bulkhead Structure separating land and water areas; primarily designed to resist earth sliding and slumping or to reduce wave erosion at the base of a cliff.
isotherm Line of equal temperature
buffer A group of substances that tends to resist change in the pH of a solution by combining with free ions.
cryptic coloration Camouflage. May be active (under control of the animal) or passive (an unalterable color or shape).
guyot A flat-topped seamount.
rain shadow An area of low precipitation on the leeward (or sheltered) side of an island or mountain. Precipitation occurs on the windward side as the air is forced to ascend the side of the island or mountain so the descending air on the leeward side is dry.
centers of action Large semi permanent belts of high or low sea level pressure distributed around the Earth that largely control the general circulation of the atmosphere and the concomitant long-term weather patterns.
atmospheric circulation cell Large circuit of air driven by uneven solar heating and the Coriolis effect. Three circulation cells form in each hemisphere. See also Ferrel cell; Hadley cell; polar cell.
biological amplification Increase in concentration of certain fat-soluble chemicals such as DDT or heavy metal compounds, in successively higher trophic levels within a food web.
nutrient Any needed substance that an organism obtains from its environment except oxygen, carbon dioxde, and water.
langmuir cells Shallow wind-driven circulation; paired helixes of moving water from windows of debris along convergence lines.
geostrophic Describing a gyre or current in balance between the Coriolis effect and gravity; literally, "turned by Earth".
offshore Direction seaward of the shore.
Carnivora The order of mammals that includes seals, sea lions, walruses, and sea otters.
biosynthesis The initial formation of life on Earth.
chiton A polyplasophoran mollusk.
free wave A progressive wave free of the forces that formed it. Compare to forced wave.
echolocation The use of sound by whales and dolphins to sense objects.
spit (sand spit) Low tongue of land, or a relatively long, narrow shoal extending from the shore.
marine pollution The introduction by humans of substances or energy into the ocean that changes the quality of the water or affects the physical or biological environment.
bias The amount by which the average of a set of values departs from a reference value.
coccolithophore A very small planktonic alga carrying discs of calcium carbonate, which contributes to biogenous sediments.
polar molecule A molecule with unbalanced charge. One end of the molecule has a slight negative charge, and the other end has a slight positive charge.
secondary coast A coast dominated by marine processes. See also primary coast: a coast on which terrestrial influences dominate.
armored beach A beach that is protected from wave and water erosion by coarse-size lag deposits.
Arctic Convergence Convergence zone between Arctic Water and Subarctic Surface Water.
precipitation Liquid or solid water that falls from the air and reaches the surface as rain, hail, or snowfall.
counterclockwise Rotation around a point in the direction opposite to that in which clock hands move. Also called anticlockwise.
crust The outermost solid layer of Earth, composed mostly of granite and basalt; the top layer of the lithosphere. The crust has a density of 2.7-2.9 g/cm3 and accounts for 0.4% of Earth's mass.
chaetognaths Free-swimming, carnivorous, pelagic, wormlike, planktonic animals; arrowworms.
isostatic equilibrium Balanced support of lighter material in a heavier, displaced supporting matrix. Analogous to buoyancy in a liquid.
mantle The layer of Earth between the crust and the core; composed of silicates of iron and magnesium. The mantle has an average density of about 4.5 gm/cm3 and accounts for about 68% of the Earth's mass.
abyssal plain Flat, cold, sediment-covered ocean floor between the continental rise and the mid-oceanic ridge at a depth of 3,700 to 5,300 meters. Abyssal plains are more extensive in the Atlantic and Indian Oceans than in the Pacific.
brackish Describing water intermediate in salinity between seawater and freshwater.
atoll A ring-shaped island of coral reefs and coral debris enclosing, or almost enclosing, a central shallow lagoon from which no land protrudes. Atolls often form over sinking, inactive volcanoes.
gravimeter A sensitive device that measures variations in the pull of gravity at different places on Earth's surface.
light Electromagnetic radiation propagated as small, nearly massless particles that behave like both a wave and a stream of particles.
Mysticeti The suborder of baleen whales.
Barents Sea One of the seas found on the Siberian shelf in the Arctic Mediterranean Sea. It is located between the White Sea to the west and the Kara Sea to the east and adjoins the Arctic Ocean proper to the north.
meroplankton The planktonic phase of the life cycle of organisms that spend only part of their life drifting in the plankton. Compare to holoplankton.
Darwin, Charles (1809-1882) English biologist. Co-discoverer (with Alfred Russell Wallace) of evolution by natural selection.
Challenger Expedition The first wholly scientific oceanographic expedition, 1872-76. Named for the steam corvette used in the voyage.
abyssal clay lithogenous sediment on the deep-sea floor composed of at least 70% clay-sized particles by weight.
buffer sublayer That part of a boundary layer where the viscous stress and the Reynolds stress have the same order of magnitude and the linear velocity profile turns smoothly into the logarithmic profile.
iceberg Floating piece of ice broken off from a glacier or ice sheet.
latent heat of vaporization Heat added to a liquid during evaporation (or released from a gas during condensation) that produces a change in state but not a change in temperature. For pure water, 585 calories per gram at 20°C (68°F).
Barents Sea One of the seas found on the Siberian shelf in the Arctic Mediterranean Sea. It is located between the White Sea to the west and the Kara Sea to the east and adjoins the Arctic Ocean proper to the north.
hypsographic curve A graph of the area of the Earth's surface above any given elevation or depth above or below sea level.
poikilotherm Organism with a body temperature that varies according to the temperature of surroundings.
dinoflagellate One of a class of microscopic single-celled flagellates, not all of which are autotrophic. The outer covering is often of stiff cellulose. Planktonic dinoflagellates are responsible for "red tides".
Darwin, Charles (1809-1882) English biologist. Co-discoverer (with Alfred Russell Wallace) of evolution by natural selection.
Chlorophyta Green algae.
cabbeling A phenomenon that occurs when two water masses with identical densities but different temperatures and salinities mix to form a third water mass with a greater density than either of its constituents.
photophore Luminous organ found on fish.
sponges Invertebrates that consist of complex aggregations of cells, bound together by protein fibers and mineral spicules.
bay mouth bar An exposed sandbar attached to a headland adjacent to a bay and extending across the mouth of the bay.
lithosphere The brittle, relatively cool outer layer of earth, consisting of the oceanic and the continental crust and the outermost, rigid layer of mantle.
drumlin A streamlined hill formed by a glacier.
abyssal zone The ocean between 13,120 and 19,680 feet deep.
backwash The water retreating down the shore after an incoming wave.
angiosperm A flowering vascular plant that reproduces by means of a seed-bearing fruit. Examples are sea grasses and mangroves.
barrier reef A coral reef surrounding an island or lying parallel to the shore of a continent, separated from land by a deep lagoon. Coral debris islands may form along the reef.
continental slope The steeply inclined edge of a continental plate below the continental shelf.
lunar tide Tide caused by gravitational and inertial interaction of the moon and Earth.
grab sampler Instrument used to remove a piece of the ocean floor for study.
berm crest The seaward limit of a beach berm.
coast The zone extending from the ocean inland as far as the environment is immediately affected by marine processes.
acid A substance that releases a hydrogen ion (H+) in solution.
pelagic sediment Sediments of the slope, rise, and deep-ocean floor that originate in the ocean.
harmonic analysis Process of separating astronomical tide-causing effects from the tide record, in order to predict the tides at any location.
baroclinic Descriptive of an atmosphere or ocean in which surfaces of pressure and density intersect at some level or levels. The state of the real atmosphere and ocean, as opposed to barotropic.
Bali Sea A regional sea which is part of the Australasian Mediterranean Sea in the southwest Pacific Ocean. It is centered at around 116°E and 8.5°S and is bordered by Bali and Sumbawa to the south and Madura to the west.
mariculture The farming of marine organisms, usually in estuaries, bays, or nearshore environments or in specially designed structures using circulating seawater. Compare aquaculture: The growing or farming of plants and animals in a water environment under controlled conditions.
commercial extinction Depletion of a resource species to a point where it is no longer profitable to harvest the species.
hypotonic Referring to a solution having a lower concentration of dissolved substances than the solution that surrounds it. Opposite of hypertonic.
Echinoidea The class of the phylum Echinodermata to which sea urchins and sand dollars belong.
Barents Sea One of the seas found on the Siberian shelf in the Arctic Mediterranean Sea. It is located between the White Sea to the west and the Kara Sea to the east and adjoins the Arctic Ocean proper to the north.
Asteroidea The class of the phylum Echinodermata to which sea stars belong.
conduction The transfer of heat through matter by the collision of one atom with another.
Perigean Tide A monthly tide of increased range that occurs when the moon is closest to earth (at perigee).
barycenter Center of mass and center rotation of the Earth-moon system, 1,700 kilometers inside Earth.
angle of incidence In meteorology, the angle of the sun above the horizon.
tropics The zone between the Tropic of Cancer (23°27'N) and the Tropic of Capricorn (23°27'S) approximating to the area of the ocean where water temperatures remain above 69°F (20°C).
Bering Sea A marginal sea located on the northern rim of the Pacific Ocean centered at approximately 58°N and 160°W. It is surrounded by Alaska to the east, Siberia to the west, and the Aleutian Island arc to the south.
phylum One of the major groups of the animal kingdom whose members share a similar body plan, level of complexity, and evolutionary history. (Plural: phyla) (The major groups of the plant kingdom are called divisions.)
extratropical cyclone A low-pressure mid-latitude weather system characterized by converging winds and ascending air rotating counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. An extratropical cyclone forms at the front between the polar and Ferrel cells.
foraminiferan One of a group of planktonic amoeba-like animals with a calcareous shell, which contributes to biogenous sediments.
medusa Free-swimming body form of many members of the phylum Cnidaria.
Cariaco Basin A 1400 m deep depression within the continental shelf of Venezuela.
continental rise The wedge of sediment forming the gentle transition from the outer (lower) edge of the continental slope to the abyssal plain. Usually associated with passive margins.
bykill Animals unintentionally killed when desirable organisms are collected.
low water Lowest elevation reached by a falling tide.
convergent plate boundary A region where plates are pushing together and where a mountain range, island arc, and/or trench will eventually form. Often a site of much seismic and volcanic activity.
lower low water The lower of the two low waters of any tidal day in a region of mixed tides.
equator 0° latitude, an imaginary line equidistant from the geographical poles. See also geographical equator and meteorological equator.
Black Sea A Mediterranean sea, centered at approximately 35°E and 44°N, that is the world's largest inland water basin.
Bivalvia The class of phylum Mollusca that includes clams, oysters, and mussels.
Antarctic Circumpolar Current The current driven by powerful westerly winds north of Antarctica. The largest of all ocean currents, it continues permanently eastward without changing direction.
Zulu time Solar time along the prime meridian passing through Greenwich, England; also known as the Greenwich Mean Time (GMT) or Universal Time.
pack ice Sea ice that forms around the permanent ice sheets of polar regions in winter and which thins and retreats in the summer.
eustatic change A worldwide change in sea level, as distinct from local changes.
berm crest The top of the berm, the highest point on most beaches. Corresponds to the shoreward limit of wave action during most high tides.
mutation A heritable change in an organism's genes.
chemical bond An energy relationship that holds two atoms together as a result of changes in their electron distribution.
plankter Informal name for a member of the plankton community.
phosphorite A sedimentary rock composed largely of calcium phosphate and largely in the form of concretions and nodules.
beach scarp Vertical wall of variable height marking the landward limit of the most recent high tides.
bay mouth bar An exposed sandbar attached to a headland adjacent to a bay and extending across the mouth of the bay.
predator An animal that feeds by capturing and eating other animals.
groin A short, artificial projection of durable material placed at a right-angle to a shore in an attempt to slow longshore transport of sand from a beach. Usually deployed in repeating units.
echo sounder A device that reflects sound off the ocean bottom to sense water depth. Its accuracy is affected by the variability of the speed of sound through water.
countercurrent A surface current flowing in the opposite direction from an adjacent surface current.
core The innermost layer of the Earth, composed primarily of iron, with nickel and heavy elements. The inner core is thought to be a solid 6,000°C (11,000°F) sphere, the outer core a 5,000°C (9,000°F) liquid mass. The average density of the outer core is about 11.8 g/cm3, and that of the inner core is about 16 g/cm3.
air mass A large mass of air with nearly uniform temperature, humidity, and density throughout.
bond An energy relationship that holds two atoms together as a result of changes in their electron distribution.
cat's-paw Patch of ripples on the water's surface, related to a discrete gust of wind.
biosynthesis The initial formation of life on Earth.
Antarctic Convergence Convergence zone encircling Antarctica between about 50° and 60°S, marking the boundary between Antarctic Circumpolar Water and Subantarctic Surface Water.
Bivalvia The class of phylum Mollusca that includes clams, oysters, and mussels.
holdfast A complex branching structure that anchors many kinds of multicellular algae to the substrate.
bioturbation The stirring of sediment by animal life.
brackish Describing water intermediate in salinity between seawater and freshwater.
abyssal clay lithogenous sediment on the deep-sea floor composed of at least 70% clay-sized particles by weight.
lagoon A shallow body of water, such as a pond or lake, usually connected to the sea.
aphotic zone The part of the ocean where no surface light can penetrate.
typhoon A hurricane in the western Pacific Ocean or China seas.
hook Spit turned landward at its outer end.
bank An undersea feature; and elevation of the sea floor, over which the depth of water is relatively shallow, but sufficient for safe surface navigation.
lag deposits Large particles left on a beach after the smaller particles are washed away.
oceanography The scientific study of all aspects of the ocean.
nekton Drifting organisms.
barrier reef A coral reef surrounding an island or lying parallel to the shore of a continent, separated from land by a deep lagoon. Coral debris islands may form along the reef.
coccolithophore A very small planktonic alga carrying discs of calcium carbonate, which contributes to biogenous sediments.
bar Offshore ridge or mound of sand, gravel, or other loose material that is submerged, at least at high tide; located especially at the mouth of a river or estuary or lying a short distance from and parallel to the beach; A submerged or emerged mound of sand, gravel, or shell material built on the ocean floor in shallow water by waves and currents.
abyssal hill Small sediment-covered inactive volcano or intrusion of molten rock less than 200 meters high, thought to be associated with sea-floor spreading. Abyssal hills punctuate the otherwise flat abyssal plain.
epicenter The point on Earth's surface directly above the focus of an earthquake.
alkaline Basic. See also base.
adaptation An inheritable structural or behavioral modification. A favorable adaptation gives a species an advantage in survival and reproduction. An unfavorable adaptation lessens a species ability to survive and reproduce.
acoustical tomography A technique for studying ocean structure that depends on pulses of low frequency sounds to sense difference in water temperature, salinity, and movement beneath the surface.
biogenic One of three major components of deep sea sediments, the other two being authigenic and detrital. Biogenic sediment consists mainly of calcite and opal produced as the hard parts of organisms and eventually precipitated.
Exclusive economic zone (EEZ) The offshore zone claimed by signatories to the 1982 United Nations Draft Convention of the Law of the Sea. The EEZ extends 200 nautical miles (370 kilometers) from a contiguous shoreline. See also United States Exclusive Economic Zone.
biodiversity The variety of different species within a habitat.
orographic effect Precipitation patterns caused by the flow of air over mountains.
higher high water Higher of the two high waters of any tidal day in a region of mixed tides.
canyon Undersea feature; a relatively narrow, deep depression with steep sides, the bottom of which generally deepends continuously, developed characteristically on some continental slopes.
epifauna Animals living attached to the sea bottom or moving freely over it.
marine energy resource Any resource resulting from the direct extraction of energy from the heat or movement of ocean water.
biogenous sediment Sediment of biological origin. Organisms can deposit calcareous (calcium-containing) or siliceous (silicon-containing) residue.
centrifugal force Outward-directed force acting on a body moving along a curved path or rotating about an axis; an inertial force.
active margin Continental margin near an area of lithospheric plate convergence. Also called Pacific Type Margin.
moraine Hills or ridges of sediment deposited by glaciers.
amnesic shellfish poisoning Poisoning caused by demic acid secreted by a diatom. It has been known to kill birds and humans and obtains its name from the fact that the pervasive symptoms in humans is amnesia.
animal A multicellular organism unable to synthesize its own food and often capable of movement.
nor'easter (northeaster) Any energetic extratropical cyclone that sweeps the eastern seaboard of North America in winter.
clumped distribution Distribution of organisms within a community in small, patchy aggregations, or clumps; the most common distribution pattern.
biodegradable Able to be broken by natural processes into simpler compounds.
atmospheric circulation cell Large circuit of air driven by uneven solar heating and the Coriolis effect. Three circulation cells form in each hemisphere. See also Ferrel cell; Hadley cell; polar cell.
acid A substance that releases a hydrogen ion (H+) in solution.
dobson unit Ozone unit, defined as 0.01 mm thickness of ozone at Standard Temperature and Pressure. If all the ozone over a certain area is compressed to 1 atm pressure at 0°C, it forms a slab of a thickness corresponding to a number of Dobson units.
CFCs A class of halogenated hydrocarbons thought to be depleting Earth's atmospheric ozone. CFCs are used as cleaning agents, refrigerants, fire extinguishing fluids, spray can propellants, and insulating foams.
Pangaea Name given by Alfred Wegener to the original "protocontinent". The breakup of Pangaea gave rise to the Atlantic Ocean and to the continents we see today.
kelp Informal name for any species of large phaeophyte.
masking pigment One of the class of pigments (such as fucoxanthin, phycobilin, and xanthophyll) present in various photosynthetic plants and that assist in the absorption of light and the transfer of its energy to chlorophyll. Also called accessory pigment.
bathybius Thomas Henry Huxley's name for an artifact of marine specimen preservation he thought was a remnant of the "primeval living slime."
mesoderm The middle layer of cells in a developing embryo.
constructive interference The addition of wave energy as waves interact producing larger waves.
anaerobic Living or functioning in the absence of oxygen.
cetaceans The whales and dolphins.
classification A way of grouping objects according to some stated criteria.
Platyhelminthes The phylum of animals to which flatworms belong.
ophiolite An assemblage of subducting oceanic lithosphere scraped off (obducted) onto the edge of a continent.
reef crest Highest portion of a coral reef on the exposed seaward edge of the reef.
eastern boundary current Weak, cold, diffuse, slow-moving current at the eastern boundary of an ocean (off the west coast of a continent). Examples include the Canary Current and the Humboldt Current.
hydrogenous sediment Sediment formed directly by precipitation from seawater. Also called authigenic sediment.
clamshell sampler Sampling device used to take shallow samples of the ocean bottom.
deadweight ton (DWT) Capacity of a vessel in tons of cargo, fuel, stores, and so on; determined by the weight of the water displace.
equilibrium theory of tides Idealized model of tides that considers earth to be covered by an ocean of great and uniform depth capable of instantaneous response to the gravitational and inertial forces of the sun and the moon.
loran Navigational system in which position is determined by measuring the difference in time of reception of synchronized radio signals; derived from the phrase "long-range navigation."
bucket temperature The surface temperature of the ocean as measured by a bucket thermometer.
picoplankton Extremely small members of the plankton community, typically 0.2 to 2 micrometers ( 4 to 40 millionths of an inch) across.
biological amplification Increase in concentration of certain fat-soluble chemicals such as DDT or heavy metal compounds, in successively higher trophic levels within a food web.
Cook, James (1728-1779) Officer in the British Royal Navy who led the first European voyages of scientific discovery.
bloom The sudden increase in phytoplankton number, usually associated with season changes.
condensation theory Premise that stars and planets accumulate from contracting, accreting clouds of galactic gas, dust, and debris.
pseudopodium Flowing, temporary extension of the protoplasm of a cell, used in locomotion or feeding.
tide The regular rising and falling of the sea that results from gravitational attraction of the moon, the sun, and other astronomical bodies acting upon the rotating Earth.
euphausiid Planktonic, shrimplike crustacean, see also krill.
dugong See sea cow.
bulkhead Structure separating land and water areas; primarily designed to resist earth sliding and slumping or to reduce wave erosion at the base of a cliff.
nudibranches Soft-bodied, gastropod mollusks; sea slugs.
projection The system used to translate the three-dimensional form of Earth onto a two-dimensional map.
calcareous ooze Ooze composed mostly of the hard remains of organisms containing calcium carbonate.
magma Molten rock capable of fluid flow. Called lava above ground.
geomorphology Study of earth's land forms and the processes that have formed them.
astrolabe An early navigation instrument that was the forerunner of the sextant.
chlorofluorocarbons A class of halogenated hydrocarbons thought to be depleting Earth's atmospheric ozone. CFCs are used as cleaning agents, refrigerants, fire extinguishing fluids, spray can propellants, and insulating foams.
Maury, Matthew (1806-1873) "Father" of physical oceanography. Probably the first person to undertake the systemic study of the ocean as a full-time occupation, and probably the first to understand the global interlocking of currents, wind flow, and weather.
auxospore A naked diatom cell without valves. Often a dormant stage in the life cycle following sexual reproduction.
wind strength Average speed of the wind, a factor in wind wave development.
salinity A measure of the total concentration of dissolved solids in seawater, usually expressed as parts per thousand; total mass, expressed in grams, of all substances dissolved in one kilogram of seawater when all carbonate has been converted to oxide, all bromine and iodine has been replaced by chlorine, and all organic compounds have been oxidized at a temperature of 480°C.
picoplankton Extremely small members of the plankton community, typically 0.2 to 2 micrometers ( 4 to 40 millionths of an inch) across.
chromatophore A pigmented skin cell that expands or contracts to affect color change.
Alaska gyre A small Pacific Ocean subpolar surface current gyre that rotates counter-clockwise south of Alaska.
bioturbation The stirring of sediment by animal life.
sill Shallow area that separates two basins from one another or a coastal bay from the adjacent ocean.
photophore Luminous organ found on fish.
ridge Long, narrow elevation of the sea floor, with steep sides and irregular topography.
Baltic Sea A dilution basin type of Mediterranean sea that is connected to and experiences limited, intermittent water exchange with the North Sea.
Cenderawasih Bay A bay on the northern coast of Irian Jaya centered at approximately 135°E and 2.5°S at the southwestern edge of the Pacific Ocean.
Platyhelminthes The phylum of animals to which flatworms belong.
Camotes Sea A small sea within the Visayan Islands that comprise the middle portion of the Philippines.
mean sea level The height of the ocean surface averaged over a few year's time.
evaporite Deposit formed by the evaporation of ocean water.
ahermatypic Describing coral species lacking symbiotic zooxanthellae and incapable of secreting calcium carbonate at a rate suitable for reef production.
calcium carbonate compensation depth The depth at which the rate of accumulation of calcareous sediments equals the rate of dissolution of those sediments. Below this depth, sediment contains little or no calcium carbonate.
drift bottle Bottle released into the sea for use in studying currents; contains a card identifying date and place of release and requesting the finder to return it with date and place of recovery.
consumer A heterotrophic organism.
Nematoda The phylum of animals to which roundworms belong.
GPS Satellite-based navigation system that provides a geographical position -- longitude and latitude -- accurate to less than 1 meter.
chlorinated hydrocarbons The most abundant and dangerous class of halogenated hydrocarbons, synthetic organic chemicals hazardous to the marine environment.
lava coast A primary coast formed by active volcanism producing laval flows that extend to the sea.
Antarctic Convergence Convergence zone encircling Antarctica between about 50° and 60°S, marking the boundary between Antarctic Circumpolar Water and Subantarctic Surface Water.
benthic zone The zone of the ocean bottom. See also pelagic zone.
physical resource Any resource that has resulted from the deposition, precipitation, or accumulation of a useful nonliving substance in the ocean or seabed. Also called a nonliving resource.
ascidian The sea squirts- a group of invertebrates that produce a larva with a primitive backbone.
divergent plate boundary A region where plates are moving apart and where new ocean or rift valley will eventually form. A spreading center forms the junction.
basalt The relatively heavy crustal rock that forms the seabeds, composed mostly of oxygen, silicon, magnesium, and iron. Its density is about 2.9 g/cm3.
chronometer A watch or clock able to maintain its accuracy on long sea voyages.
adaptation An inheritable structural or behavioral modification. A favorable adaptation gives a species an advantage in survival and reproduction. An unfavorable adaptation lessens a species ability to survive and reproduce.
attenuation Decrease in the energy of a wave or beam of particles occurring as the distance from the source increases; caused by absorption, scattering, and divergence from a point source.
andesite A volcanic rock intermediate in composition between basalt and granite; associated with subduction zones.
equinoxes Days of the year when the sun stands directly above the equator, so that day and night are of equal length around the world. The vernal equinox occurs about March 21, and the autumnal equinox occurs September 22-23.
Aves The class of birds.
Bowen ration The ratio of the amount of sensible to that of latent heat lost by a surface to the atmosphere by the processes of conduction and turbulence.
constructive interference The addition of wave energy as waves interact producing larger waves.
pollutant A harmful substance or heat energy introduced into an ecosystem by human activities.
disthermal zone The zone of stable temperature below the thermocline.
big bang The hypothetical event that started the expansion of the universe from a geometric point. The beginning of time.
capillary wave A tiny wave with a wavelength of less than 1.73 centimeters (0.68 inch), whose restoring force is surface tension; the first type of wave to form when the wind blows.
Black Sea A Mediterranean sea, centered at approximately 35°E and 44°N, that is the world's largest inland water basin.
Chondrichthyes The class of fishes with cartilagenous skeletons: the sharks, skates, rays, and chimaeras.
neritic zone The zone of open water near shore, over the continental shelf.
submersible A small underwater vehicle designed for deep sea research and other tasks.
atoll A ring-shaped island of coral reefs and coral debris enclosing, or almost enclosing, a central shallow lagoon from which no land protrudes. Atolls often form over sinking, inactive volcanoes.
aphelion The point in the orbit of a satellite where it is farthest from the sun; opposite of perihelion.
basin An undersea feature; a depression, in the sea floor, more or less equidimensional in plan and of variable extent; large depression of the sea floor having about equal dimensions of length and width.
Antarctic Circumpolar Current The current driven by powerful westerly winds north of Antarctica. The largest of all ocean currents, it continues permanently eastward without changing direction.
Agnatha The class of jawless fishes: hagfishes and lampreys.
symbiosis The close beneficial feeding relationship between two species.
attenuation Decrease in the energy of a wave or beam of particles occurring as the distance from the source increases; caused by absorption, scattering, and divergence from a point source.
continental crust The solid masses of the continents, composed primarily of granite.
continental rise Gently sloping base of the continental slope.
bathymetry The discovery and study of submerged contours.
continental margin The submerged outer edge of a continent, made of granitic crust. Includes the continental shelf and continental slope. Compare ocean basin.
continental margin The submerged outer edge of a continent, made of granitic crust. Includes the continental shelf and continental slope. Compare ocean basin.
Bohol Sea A small sea centered in the Philippines at about 124°E and 9°S.
benthic zone The zone of the ocean bottom. See also pelagic zone.
contour current A bottom current made up of dense water that flows around (rather than over) seabed projections.
Annelida The phylum of animals to which segmented worms belong.
calcareous Of or containing calcium carbonate or another, usually insoluble, calcium salt.
absorption Conversion of sound or light energy into heat.
standing crop Biomass present at any given time.
bacteria Single-celled prokaryotes, organisms lacking membrane-bound organelles.
Agnatha The class of jawless fishes: hagfishes and lampreys.
nonconservative resource Any use of the ocean in place, such as transportation of people and commodities by sea, recreation, or waste disposal.
Odontoceti The suborder of toothed whales.
cyclone A weather system with a low-pressure area in the center around which winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Not to be confused with a tornado, a much smaller weather phenomenon associated with sever thunderstorms. Se also extratropical cyclone; tropical cyclone.
Brazil Basin An ocean basin located off the eastern coast of Brazil in the west-central Atlantic Ocean.
chlorinity A measure of the amount of chlorine or other halides in water (especially seawater).
barrier island A long, narrow, wave-built island lying parallel to the mainland and separated from it by a lagoon or bay. Compare sea island.
Antarctic Circle The line of latitude at 66°33'S marking the northern limit of the Antarctic region. The imaginary line around the Earth, parallel to the equator at 66°33'S, marking the southernmost limit of sunlight at the June solstice. The Antarctic Circle marks the northern limit of the area within which, for one day or more each year, the sun does not sea (around December 21) or rise (around June 21).
buffer A group of substances that tends to resist change in the pH of a solution by combining with free ions.
bloom High concentration of phytoplankton in an area, caused by increased reproduction; often produces discoloration of water. See red tide.
zooplankton One of the two groups into which plankton are divided, the other being phytoplankton. Zooplankton are a large group of micro- and macroscopic animals ranging in size from a fraction of a millimeter to 30-50 millimeters; Small animals that spend all or part of their life cycles floating in the surfaces layers of the ocean.
flow method A method of current study that measures the current as it floats past a fixed object.
rafting Transport of sediment, rock, silt, and other land matter out to sea by ice, logs, and the like, with the deposition of the rafted material when the carrying agent melts or disintegrates.
Law of the Sea Collective term for laws and treaties governing the commercial and practical use of the ocean.
neap tide The time of smallest variation between high and low tides occurring when Earth, moon, and sun align at right angles. Neap tides alternate with spring tides, occurring at two week intervals.
microplankton Net plankton, composed of individuals from 0.07-1 mm in size but not large enough to be retained by a small mesh net.
coral reef A linear mass of calcium carbonate (aragonite and calcite) assembled from coral organisms, algae, mollusks, worms, and so on. Coral may contribute to less than half of the reef material.
cell The basic organizational unit of life on this planet.
Arctic Circle The line of latitude at 66°33'N marking the southern limit of where the sun does not set in June or rise at December solstices.
Bay of Bengal The northeastern arm of the Indian Ocean, located between India and Burma.
jetty Structure located to influence currents or to protect the entrance to a harbor or river from waves.
passive sonar A device that detects the intensity and direction of underwater sounds.
food General term for organic molecules capable of providing energy to heterotrophs when combined with oxygen during biochemical respiration.
backwash The water retreating down the shore after an incoming wave.
eddy A circular movement of water usually formed where currents pass obstructions, or between two adjacent currents flowing in opposite directions, or along the edge of a permanent current.
angle of incidence In meteorology, the angle of the sun above the horizon.
Agnatha The class of jawless fishes: hagfishes and lampreys.
wave The disturbance in water caused by the movement of energy through the water.
atom The smallest particle of an element that exhibits the characteristics of that element.
winter berm A relatively permanent berm that is formed by high energy waves in the winter.
backshore That part or zone of a beach profile that extends landward from the sloping foreshore to a point of either vegetation development or a change of physiography, e.g. a sea cliff or a dune field.
breakwater Structure protecting a shore area, harbor, anchorage, or basin from waves; a type of jetty.
Panthalassa Name given by Alfred Wegener to the ocean surrounding Pangaea.
ecology Study of the interactions of organisms with one another and with their environment.
coastal cell The natural sector of a coastline in which sand input and sand outflow are balanced.
exoskeleton A strong, lightweight, form-fitted external covering and support common to animals of the phylum Arthropoda. The exoskeleton is made partly of chitin and may be strengthened by calcium carbonate.
coral reef A linear mass of calcium carbonate (aragonite and calcite) assembled from coral organisms, algae, mollusks, worms, and so on. Coral may contribute to less than half of the reef material.
summer berm A seasonal berm that is built by low energy waves during the summer and removed by high energy waves in the winter.
high tide The high-water position corresponding to a tidal crest.
hydrogenous sediment Sediment precipitated from substances dissolved in water.
proton A positively charged particle at the center of an atom.
crest Highest part of a progressive wave above average water level.
beach The region of the shore where loose material, sand, mud, or pebble, are deposited between high- and low-water marks.
nonconservative constituent An element whose proportion in seawater varies with time and place, depending on biological demand or chemical reactivity. An element with a short residence time. For example, iron, aluminum, silicon, trace nutrients, dissolved oxygen, and carbon dioxide.
auxospore A naked diatom cell without valves. Often a dormant stage in the life cycle following sexual reproduction.
Magellan, Ferdinand (c. 1480-1521) Portuguese navigator in the service of Spain who led the first expedition to navigate the Earth, 1519-22. He was killed in the Philippines.
nautical chart A chart used for marine navigation.
berm crest The seaward limit of a beach berm.
accessory pigment One of the class of pigments (such as fucoxanthin, phycobilin, and xanthophyll) present in various photosynthetic plants and that assist in the absorption of light and the transfer of its energy to chlorophyll. Also called masking pigment.
continental drift The theory that the continents move slowly across the surface of the earth.
perihelion The point in the orbit of a satellite where it is closest to the sun; opposite of aphelion.
chitin A complex nitrogen-rich carbohydrate from which parts of arthropod exoskeletons are constructed.
Ophiuroidea The class of the phylum Echinodermata to which brittle stars belong.
carbon cycle The cycling of carbon in the form of carbon dioxide, carbonates, organic compounds, etc. between various reservoirs, e.g. the atmosphere, the oceans, land and marine biota and, on geological time scales, sediments, and rocks.
sun tide Portion of the tide generated solely by the sun's tide-raising force, as distinguished as that from the moon.
longshore bar A submerged or exposed line of sand lying parallel to shore and accumulated by wave action.
bioluminescence Biologically produced light.
bathyal zone The marine ecologic zone that lies deeper than the continental shelf but shallower than the deep ocean floor, i.e. those depths corresponding to the locations of the continental slope and rise.
Beaufort scale Scale of wind forces by range of velocity; scale of sea state created by winds of these velocities
primary consumer Initial consumer of primary producers. The consumers of autotrophs; the second level in food webs.
biological factor A biologically generated aspect of the environment, such as predation or metabolic waste products, that affects living organisms. Biological factors usually operate in association with purely physical factors such as light and temperature.
central water A term used to identify thermocline water masses in all three oceans. The water arrives at a thermocline via a process known as subduction.
zooanthellae Single-celled photosynthetic organisms that live in coral tissues in a symbiotic relationship.
focus The location of an earthquake within earth. Focus is specified by identifying latitude, longitude, and depth of the earthquake. See also epicenter.
absolute dating Determining the age of a geological sample by calculations of radioactive decay and/or its position in relation to other samples.
navigation The science of position fixing and course plotting, using astronomical and other observations.
high-energy coast A coast exposed to large waves.
leading margin Also known as active margin. The edge of the overriding plate at a trench or subduction zone.
Arctic Ocean An ice-covered ocean north of the continents of North America and Eurasia.
authogenic sediment Sediment formed directly by precipitation from seawater. Also called hydrogenous sediment.
wave ray Line indicating the direction waves travel; drawn at right angles to the wave's crest.
longshore trough Submerged excavation parallel to shore adjacent to an exposed sandy beach. Caused by the turbulence of water returning to the ocean after each wave.
evolution Change. The maintenance of life under constantly changing conditions by continuous adaptation of successive generations of a species to its environment.
coastal upwelling Upwelling adjacent to a coast, usually induced by wind.
flood tide Rising tide; the period of the tide between low water and the next high water.
convection cell Movement within a fluid resulting from differential heating and cooling of the fluid. Convection produces mass transport or mixing of the fluid.
upwelling The rising of deep, cold-nutrient-laden waters into the surface layers, close to continental coasts
amphidromic point A "no-tide" point in an ocean caused by basin resonances, friction, and other factors around which tide crests rotate. About a dozen amphidromic points exist in the world ocean. Also sometimes called a node.
low tide terrace The smooth, hard-packed beach seaward of the beach scarp on which waves expend most of their energy. Site of the most vigorous onshore and offshore movement of sand.
coral Any of over 6,000 species of small cnidarians, many of which are capable of generating hard calcareous (aragonite CaCO3) skeletons.
littoral Area of the shore between mean high water and mean low water; the intertidal zone.
backwash Water returning to the ocean from waves washing onto a beach.
breakwater Structure protecting a shore area, harbor, anchorage, or basin from waves; a type of jetty.
greenhouse gases Gases in Earth's atmosphere that cause the greenhouse effect; include carbon dioxide, methane, and CFCs.
biological pump Photosynthetic transfer of carbon as CO2 from the atmosphere to the ocean in the form of organic molecules; carbon is transferred to intermediate and deep-ocean water when organic material sinks and decays.
coast The zone extending from the ocean inland as far as the environment is immediately affected by marine processes.
ectoderm The outermost layer of cells in a developing embryo.
planet A smaller, usually nonluminous body orbiting a star.
beach berm The nearly horizontal portion of a beach formed by the deposition of sediment by receding waves. A beach may have more than one berm.
tidal day Time interval between two successive passes of the moon over a meridian, approximately 24 hours and 50 minutes.
acoustic profiling The use of seismic energy to measure sediment thickness and layering on the sea floor.
rift valley Trough formed by faulting along a zone in which plates move apart and new crust is created, such as along the crest of a ridge system.
latitude A measure of north-south location, relative to the equator at 0˚.
clay Sediment particle smaller than 0.004mm in diameter; the smallest sediment size category.
chlorinated hydrocarbons The most abundant and dangerous class of halogenated hydrocarbons, synthetic organic chemicals hazardous to the marine environment.
polar reversal The periodic reversal of earth's magnetic field where the north magnetic pole becomes the south magnetic pole and vice versa.
mutualism A symbiotic interaction between two species that is beneficial to both.
fetch The uninterrupted distance over which the wind blows without a significant change in direction, a factor in wind wave development.
lower high water The lower of the two high waters of any tidal day in a region of mixed tides.
bathythermograph A device developed by Athelstan Spilhaus in 1938 to measure temperature/depth profiles in the ocean. Replaced the oceanograph.
adhesion Attachment of water molecules to other substances of hydrogen bonds. Wetting.
absorption Conversion of sound or light energy into heat.
sea smoke Type of fog caused by dry, cold air moving over warmer water.
side-scan sonar High-resolution sound-imaging of the seabed.
continental shelf break Zone along which there is a marked increase of slope at the outer margin of a continental shelf.
backwash Water returning to the ocean from waves washing onto a beach.
neap tides Tides with much smaller ranges than spring tides, that occur while the gravitational pulls of the moon and sun on the oceans work against each other.
capillary wave A wave on a fluid interface for which the restoring force is surface tension.
limiting factor A physical or biological environmental factor whose absence or presence in an inappropriate amount limits the normal actions of an organism.
rogue wave A single, unusually high wave created by the constructive interference of two or more smaller waves.
ITCZ Intertropical convergence zone; The equatorial area at which the trade winds converge. The ITCZ usually lies at or near the meteorological equator. Also called the doldrums.
oolith Small, rounded, accretionary body of calcium carbonate. Created by precipitation of calcium carbonate in shallow, warm seawater due to a change in water temperature or acidity.
calcareous ooze Partially composed organic matter mixed with a quantity of calcareous material on the bottom of some bodies of water; a fine-grained, deep-sea deposit of pelagic origin containing more than 30% calcium carbonate derived from the skeletal material of various plankton. It is the most extensive deposit on the ocean floor but restricted to depths less than about 3500 m due to the carbon compensation depth.
adsorption Attraction of ions to a solid surface.
Bransfield Strait A strait located between the northern tip of the Antarctica Peninsula and the South Shetland Islands. 120 km wide and extends 460 km from Clarence Island to Low Island.
acid rain Rain containing acids and acid-forming compounds such as sulfur dioxide and oxides of nitrogen.
plankter Informal name for a member of the plankton community.
backshore Sand on the shoreward side of the berm crest, sloping away from the ocean.
abyssal zone The ocean between 13,120 and 19,680 feet deep.
basalt The relatively heavy crustal rock that forms the seabeds, composed mostly of oxygen, silicon, magnesium, and iron. Its density is about 2.9 g/cm3.
adhesion Attachment of water molecules to other substances of hydrogen bonds. Wetting.
physiographic map Portrayal of earth's features by perspective drawing.
Antarctic Ocean An ocean in the Southern Hemisphere bounded to the north by the Atlantic Convergence and to the south by Antarctica.
precipitate (1) A solid substance formed in an aqueous reaction. (2) The process by which a solute forms in and falls from a solution. The falling of water or ice from the atmosphere.
invertebrate Animal lacking a backbone.
baleen The interleaved, hard, fibrous, hornlike filters within the mouth of baleen whales.
anaerobic Living or functioning in the absence of oxygen.
excess volatiles A compound found in the ocean and atmosphere in quantities greater than can be accounted for by the weathering of surface rock. Such compounds probably entered the atmosphere and ocean from deep crustal and upper mantle sources through volcanism.
apogee The point in the orbit of a satellite farthest from the main body; opposite of perigee.
accretion An increase in the mass of a body by accumulation or a clumping of smaller particles.
Black Sea A Mediterranean sea, centered at approximately 35°E and 44°N, that is the world's largest inland water basin.
advection Horizontal or vertical transport of seawater, as by a current.
barrier island A long, narrow, wave-built island lying parallel to the mainland and separated from it by a lagoon or bay. Compare sea island.
density curve A graph showing the relationship between a fluid's temperature or salinity and its density.
active sonar A device that generates underwater sound from special transducers and analyzes the returning echoes to gain information of geological, biological, or military importance.
principle of constant proportions The proportions of major conservative elements in seawater remain nearly constant, though total salinity may change with location Also called Forchhammer's principle.
chemical equilibrium In seawater, the condition in which the proportion and amounts of dissolved salts per unit volume of ocean are nearly consistent.
mixed layer The upper layer of ocean in which temperature and salinity are relatively constant with depth. Depending on local conditions, the surface zone may reach to 1,000 meters (3,300 feet) or be absent entirely. Also called the surface zone.
Bohol Sea A small sea centered in the Philippines at about 124°E and 9°S.
bucket thermometer A thermometer with an insulated container around the bulb.
Polynesia A large group of Pacific Islands extending from the Hawaiian Islands south to New Zealand and east to Easter Island.
accretion An increase in the mass of a body by accumulation or a clumping of smaller particles.
buffer factor Defined as the fractional changed in atmospheric CO2 divided by the fractional change in oceanic DIC after equilibrium has been reached.
Antarctic Ocean An ocean in the Southern Hemisphere bounded to the north by the Atlantic Convergence and to the south by Antarctica.
Arctic Convergence Convergence zone between Arctic Water and Subarctic Surface Water.
calving Breaking away of a mass of ice from its parent glacier, iceberg, or sea ice formation.
beach face The sloping section of a beach profile below the beach berm which is normally exposed to the action of the wave swash.
backwash The water retreating down the shore after an incoming wave.
nautical mile The length of 1 minute of latitude, 6,076 feet, 1.15 statute miles, or 1.85 kilometers.
channel A body of water that connects two larger bodies of water. A channel is also part of a river or harbor that is deep enough to let ships sail through.
paleomagnetism The "fossil", or remanent, magnetic field of a rock.
electromagnetic radiation Waves of energy formed by simultaneous electrical and magnetic oscillations, the electromagnetic spectrum is the continuum of all electromagnetic radiation from low-energy radio waves to high-energy gamma rays, including visible light.
storm berm See winter berm
ozone O3, the triatomic form of oxygen. Ozone in the atmosphere protects living things from some of the harmful effects of the sun's ultraviolet radiation.
cartographer A person who makes maps and charts.
polar regions The cold zones between the poles and either the Arctic or Antarctic circles.
copepod Small, shrimplike member of the zooplankton; in the class Crustacea.
mineral A naturally occurring inorganic crystalline material with a specific chemical composition and structure.
Bjerknes, Vilhelm (1862-1951) Pioneering Norwegian physicist and discoverer of the nature and formation of extratropical cyclones, which cause most mid-latitude weather.
phosphorite A sedimentary rock composed largely of calcium phosphate and largely in the form of concretions and nodules.
chlorophyll A pigment responsible for trapping sunlight and transferring its energy to electrons, thus initiating photosynthesis.
alluvial plain A flat deposit of terrestrial sediment eroded by water from higher elevations.
pinnipeds The seals, walruses, and sea lions.
algae Collective term for nonvascular plants possessing chlorophyll and capable of photosynthesis. Simple plants found as single cells or as seaweeds.
cell The basic organizational unit of life on this planet.
Cephalopoda The class of the phylum Mollusca that includes squid, octopuses, and nautiluses.
partially mixed estuary An estuary in which an influx of seawater occurs beneath a surface layer of fresh water flowing seaward. Mixing occurs along the junction.
deposition Accumulation, usually of sediments.
baroclinic Descriptive of an atmosphere or ocean in which surfaces of pressure and density intersect at some level or levels. The state of the real atmosphere and ocean, as opposed to barotropic.
hurricane A large tropical cyclone in the North Atlantic or eastern Pacific, whose winds exceed 118 kilometers (74 miles) per hour.
aphelion The point in the orbit of a satellite where it is farthest from the sun; opposite of perihelion.
nonrenewable resource Any resource that is present on Earth in fixed amounts and cannot be replenished.
abyssopelagic Oceanic zone from 4000m to the deepest depth.
natural selection A mechanism of evolution that results in the continuation of only those forms of life best adapted to survive and reproduce in their environment.
convection current A single closed-flow circuit of rising warm material and falling cool material.
overfishing The commercial fishing of natural populations so that breeding does not replenish what has been removed.
La Niña An event during which normal tropical Pacific atmospheric and oceanic circulation strengthens and the surface temperature of the eastern South Pacific drops below average values. Usually occurs at the end of an ENSO event. See also ENSO.
polar front Boundary between the polar cell and the Ferrell cell in each hemisphere.
passive margin Continental margin near an area of lithospheric plate divergence. Also called Atlantic-type margin.
Chlorophyta Green algae.
Arctic Circle The line of latitude at 66°33'N marking the southern limit of where the sun does not set in June or rise at December solstices.
Hadley cell The atmospheric circulation cell nearest the equator in each hemisphere. Air in these cells rises near the equator because of strong solar heating there and falls because of cooling at about 30° latitude. See also trade winds.
by-catch See incidental catch.
Franklin, Benjamin (1706-1790) American scientist and statesman. Published the first chart of an ocean current in 1769.
endoderm The innermost layer of cells in a developing embryo.
Algulhas Current A warm current that carries Indian Ocean water around the southern tip of Africa and into the Atlantic Ocean.
cephalopod An advanced group of mollusks that includes the squids, octopuses, and cuttlefishes.
bioluminescence The generation of light by living organisms using the enzyme luciferase.
adsorption Attraction of ions to a solid surface.
filament Chain of living cells.
West Wind Drift The current driven by powerful westerly winds north of Antarctica. The largest of all ocean currents, continues permanently eastward without changing direction. See Antarctic Circumpolar Current: The current driven by powerful westerly winds north of Antarctica. The largest of all ocean currents, it continues permanently eastward without changing direction.
Prince Henry the Navigator Established a center at Sagres, Portugal, for the study of marine science and navigation in the mid-1450's.
biogeochemical sediment Natural processes that recycle nutrients in various chemical forms from the nonliving environment to the living organisms and then back to the nonliving environment.
energy The capacity to do work.
cnidoblast Type of cell found in members of the phylum Cnidaria that contains a stinging capsule. The threads that evert from the capsules assist in capturing prey and repelling aggressors.
bacteria Single-celled prokaryotes, organisms lacking membrane-bound organelles.
advection Horizontal or vertical transport of seawater, as by a current.
diurnal tide A tidal cycle of one high tide and one low tide per day.
intermediate-depth water wave A wave moving through water deeper than 1/20 but shallower than 1/2 its wavelength. Also called a transitional wave.
brash ice A type of sea ice; accumulations of floating ice made up of fragments not more than 2 meters across; the wreckage of other forms of ice.
pelagic zone The water column.
krill Euphausia superba, a thumb-size crustacean common in Antarctic waters.
Caribbean Sea The largest marginal sea of the Atlantic Ocean, with a surface area twice that of the Mediterranean Sea.
freezing point The temperature at which a solid can begin to form as a liquid is cooled.
metamerism Segmentation; repeating body parts.
Ferrel, William (1817-1891) The American scientist who discovered the mid-latitude circulation cells of each hemisphere.
overfishing Harvesting so many fish that there is not enough breeding stock left to replenish the species.
convection current A single closed-flow circuit of rising warm material and falling cool material.
beach scarp Vertical wall of variable height marking the landward limit of the most recent high tides.
multicellular algae Algae with bodies consisting of more than one cell. Examples are kelp and ulva.
progressive wave A wave of moving energy in which the wave form moves in one direction along the surface (or junction) of the transmission medium (or media).
lysocline Depth at which calcareous skeletal material first begins to dissolve.
primary coast Coast on which terrestrial influences dominate. See also secondary coast: a coast dominated by marine processes.
poikilotherm Organism with a body temperature that varies according to the temperature of surroundings.
ciguatera Toxin found in fish of tropical regions; produced by dinoflagellates.
primary productivity The synthesis of organic materials from inorganic substances by photosynthesis or chemosynthesis. Expressed in grams of carbon bound into carbohydrate per unit area per unit of time (g C/m2/yr).
hadal zone The deepest zone of the ocean, below a depth of 5,000 meters (16,500 feet).
corange lines In a rotary tide, lines of equal tidal range about the amphidromic point.
chart A map that depicts mostly water and the adjoining land areas.
plunging wave Breaking wave in which the upper section topples forward and away form the bottom, forming an air-filled tube.
catastrophism The theory that the Earth's surface features are formed by catastrophic forces such as the biblical flood. Catastrophists believe in a young Earth and a literal interpretation of the biblical account of Creation.
continental drift The theory that the continents move slowly across the surface of the earth.
Bali Sea A regional sea which is part of the Australasian Mediterranean Sea in the southwest Pacific Ocean. It is centered at around 116°E and 8.5°S and is bordered by Bali and Sumbawa to the south and Madura to the west.
La Niña The periodic cooling of the surface waters in the eastern Pacific.
absorption Conversion of sound or light energy into heat.
ENSO Acronym for the coupled phenomena of El Niño and the Southern Oscillation. El Niño is a southward-flowing nutrient-poor current of warm water off the coast of western South America, caused by a breakdown of trade-wind circulation. Southern Oscillation is a reversal of airflow between normally low atmospheric pressure over the western Pacific and normally high pressure over the Eastern Pacific, and is the cause of El Niño.
biogenous sediment Sediment of biological origin. Organisms can deposit calcareous (calcium-containing) or siliceous (silicon-containing) residue.
photosynthesis The process by which autotrophs bind light energy into the chemical bonds of food with the aid of chlorophyll and other substances. The process uses carbon dioxide and water as raw materials and yields glucose and oxygen.
isostasy The equilibrium of the earth's crust, a condition in which the forces tending to elevate balance those tending to depress; the state in which pressures from every side are equal
desiccation Drying.
coral Any of over 6,000 species of small cnidarians, many of which are capable of generating hard calcareous (aragonite CaCO3) skeletons.
Challenger Expedition The first wholly scientific oceanographic expedition, 1872-76. Named for the steam corvette used in the voyage.
eurythermal Describing an organism able to tolerate a wide range of temperature.
latent heat of fusion Heat removed from a liquid during freezing (or added to a solid during thawing) that produces a change in state but not a change in temperature. For pure water, 80 calories per gram at 0°C (32°F).
backshore Sand on the shoreward side of the berm crest, sloping away from the ocean.
Aves The class of birds.
continental shelf Gradually sloping submerged extension of a continent composed of granitic rock overlain by sediments. Has features similar to the edge of the nearby continent.
anoxic Deficient in oxygen.
aseimic ridge see transverse ridge
reverse osmosis The process of producing fresh water from seawater by forcing the water molecules through a semipermeable membrane, leaving behind salt ions and other impurities.
phycobilin A reddish accessory pigment found in red algae.
berm crest The seaward limit of a beach berm.
abyssal hill Small sediment-covered inactive volcano or intrusion of molten rock less than 200 meters high, thought to be associated with sea-floor spreading. Abyssal hills punctuate the otherwise flat abyssal plain.
biogenic One of three major components of deep sea sediments, the other two being authigenic and detrital. Biogenic sediment consists mainly of calcite and opal produced as the hard parts of organisms and eventually precipitated.
asthenosphere The hot, plastic layer of the upper mantle below the lithosphere, extending some 350 to 650 kilometers below the surface. Convection currents within the asthenosphere power plate tectonics.
longshore drift The movement of beach material parallel to the coastline by combined wind and wave action.
action plan for the human environment In 1972 this UN program established 12 worldwide environmental units and determined procedures for assessing and monitoring various sources of pollution.
bioturbation Reworking of sediments by organisms that burrow into them and ingest them.
Arctic Circle The line of latitude at 66°33'N marking the southern limit of where the sun does not set in June or rise at December solstices.
moon tide Portion of the tide generated solely by the moon's tide-raising force, as distinguished from that of the sun.
dissolution The dissolving by water of minerals in the rocks.
seismic survey The use of high-intensity sound waves to examine deep geological structures.
ascidian The sea squirts- a group of invertebrates that produce a larva with a primitive backbone.
Protista The kingdom of single-celled nucleated organisms to which protozoa, diatoms, and dinoflagellates belong. Also called Protoctista.
monsoon A pattern of wind circulation that changes with the season. Also, the rainy season in areas with monsoon wind patterns.
plunging wave Breaking wave in which the upper section topples forward and away form the bottom, forming an air-filled tube.
plankton bloom A sudden increase in the number of phytoplankton cells in a volume of water.
artificial system of classification A method of classifying an object based on attributes other than its reason for existence, its ancestry, or its origin. Compare natural system of classification.
gabbro A coarse-grained, dark igneous rock, rich in iron and magnesium, the slow-cooling equivalent of basalt.
protostar Tightly condensed knot of material that has not yet attained fusion temperature.
xanthophyll A yellow or brown accessory pigment that gives some marine autotrophs a yellow or brown appearance.
celestial navigation The technique of finding one's position on Earth by reference to the apparent position of stars, planets, the moon, and the sun.
astrolabe An early navigation instrument that was the forerunner of the sextant.
demersal fish Fish living near and on the bottom.
alveoli A tiny thin-walled capillary rich sack in the lungs where the exchange of oxygen and carbon dioxide take place.
habitat The place where an individual or population of a given species lives. Its "mailing address".
pinnipeds The seals, walruses, and sea lions.
Bowen ration The ratio of the amount of sensible to that of latent heat lost by a surface to the atmosphere by the processes of conduction and turbulence.
carrageenan Substance produced by certain algae that acts as a thickening agent.
compass An instrument for showing direction by means of a magnetic needle swinging freely on a pivot and pointing to magnetic north.
compound A substance composed of two or more elements in a fixed proportion.
Bay of Bengal The northeastern arm of the Indian Ocean, located between India and Burma.
mercator projection A map projection in which the surface of earth is projected onto a cylinder. Distortion is great at high latitudes and the poles cannot be shown. Mercator projections are frequently used for navigation because a straight line drawn on them is a line of true direction or constant compass heading.
pollutant A substance that causes damage by interfering directly or indirectly with an organism's biological processes.
convergence zone The line along which waters of different density converge. Convergence zones form the boundaries of tropical, sub-tropical, temperate, and polar regions.
gyre circuit of mid-latitude currents around the periphery of an ocean basin. Most oceanographers recognize five gyres plus the Antarctic Circumpolar Current.
nautical mile The length of 1 minute of latitude, 6,076 feet, 1.15 statute miles, or 1.85 kilometers.
forced wave A progressive wave under the continuing influence of the forces that formed it. Compare to free wave.
centers of action Large semi permanent belts of high or low sea level pressure distributed around the Earth that largely control the general circulation of the atmosphere and the concomitant long-term weather patterns.
bank An undersea feature; and elevation of the sea floor, over which the depth of water is relatively shallow, but sufficient for safe surface navigation.
conservative constituent An element that occurs in constant proportion in seawater. For example, chlorine, sodium, and magnesium.
Celtic Sea A shallow embayment of the eastern North Atlantic bounded by Southern Ireland. Separated from the Irish Sea by a line drawn from Ramsey Island to Carnsore Point and from the English Channel by a line drawn from Ushant to Lands End.
pelagic Of the open ocean. Refers to the water above the deep-ocean basins, sediments of oceanic origin, or organisms of the open ocean.
map A representation of Earth's surface, usually depicting mostly land areas. See also chart.
electrodialysis Separation process in which electrodes of opposite charge are placed on each side of a semipermeable membrane to accelerate the diffusion of ions across the membrane.
Balearic Sea One of the seas that comprise the western basin of the Mediterranean Sea which is sometimes called the Catalan Sea. It lies between The Iberian coast and the Balearic Islands (Ibiza, Mallorca, Menorca) in the northwestern Mediterranean.
buoyancy The ability of an object to float in a fluid by displacement of a volume of fluid equal to it in mass.
oceanus Latin form of okeanos, the Greek name for the "ocean river" past Gibraltor.
manganese nodules Rounded, layered lumps found on the deep-ocean floor that contain on average about 18% manganese, 17% iron, with smaller amounts of nickel, cobalt, and copper and traces of two dozen other metals; a hydrogenous sediment.
El Niño The periodic warming of the surface waters in the east Pacific that stops upwelling of nutrients.
fathom A unit of length equal to 1.8m (6ft); used to measure water depth.
intertidal zone The marine zone between the highest high-tide point on a shoreline and the lowest low-tide point. The intertidal zone is sometimes subdivided into four separate habitats by height above tidal datum, typically numbered 1 to 4, land to sea.
bathyal zone The ocean between about 200 and 4,000 meters deep.
wind wave Gravity wave formed by transfer of wind energy into water. Wavelengths from 60 to 150 meters (200 to 500 feet) are most common in the open ocean.
magma Molten rock found below Earth's crust that is ejected by volcanoes and emerges at ocean ridges as lava.
bathythermograph A device developed by Athelstan Spilhaus in 1938 to measure temperature/depth profiles in the ocean. Replaced the oceanograph.
alkaline Basic. See also base.
bathypelagic zone The ocean between 656 and 13,120 feet deep; One of five vertical ecological zones into which the deep sea is sometimes divided. This is the zone starting from 100 to 700 m deep (coinciding with the upper limit of the psychrosphere) at the 10°C isotherm.
mangrove Large flowering shrub or tree that grows in dense thickets or forests along muddy or silty tropical coasts.
international date line An imaginary line through the Pacific Ocean roughly corresponding to 180° longitude, to the east of which, by international agreement, the calendar date is one day earlier than to the west.
climax community A stable, long-established community of self-perpetuating organisms that tends not to change with time.
bilateral symmetry Body structure having left and right sides that are approximate mirror images of each other. Examples are crabs and humans. Compare radial symmetry.
neritic zone Zone from high tide to the continental shelf break.
minus tide Low tide level below the mean value of the low tides or the zero tidal depth reference.
rotary current Tidal current that continually changes its direction of flow through all points of the compass during a tidal period.
ahermatypic Describing coral species lacking symbiotic zooxanthellae and incapable of secreting calcium carbonate at a rate suitable for reef production.
biomass The mass of living material in a given area or volume of habitat.
depositional coast A coast in which processes that deposit sediment exceed erosive processes.
Plantae The kingdom to which multicellular vascular autotrophs belong.
detritus Any loose material, especially decomposed, broken, and dead organic materials.
continental slope The sloping transition between the granite of the continent and the basalt of the seabed. The true edge of a continent.
salt budget Balance between the rates of salt addition to and removal from a body of water.
epipelagic zone The lighted, or photic, zone in the ocean.
adiabatic Pertaining to a change in the temp of a mass resulting from compression or expansion; requires no addition of heat to or loss of heat from the substance.
Bowen ration The ratio of the amount of sensible to that of latent heat lost by a surface to the atmosphere by the processes of conduction and turbulence.
great circle The intersection of a plane passing through the center of the earth with the surface of the earth. Great circles are formed by the equator and any two meridians of longitude 180° apart.
bathyscaphe Deep-diving submersible designed like a blimp, which uses gasoline for buoyancy and can reach the bottom of the deepest ocean trenches.
oceanic zone The zone of open water away from shore, past the continental shelf.
chlorinity A measure of the content of chloride, bromine, and iodide ions in seawater. We may derive salinity from chlorinity by multiplying by 1.80655.
continental crust Solid, outer layers of earth, including the rocks of the continents
hydrostatic pressure The constant pressure of water around a submerged organism.
triploid Condition in which cells have three sets of chromosomes.
buoy Floating object to float due to the support of the fluid the body is in or on.
cetacea The order of mammals that includes porpoises, dolphins and whales.
Coriolis effect The apparent deflection of a moving object from its initial course when its speed and direction are measured in reference to the surface of the rotating Earth. The object is deflected to the right of its anticipated course in the Northern hemisphere and to the left in the Southern Hemisphere. The deflection occurs for any horizontal movement of objects and has no effect at the equator.
acoustic thermometry of ocean climate ATOC; the measurement of ocean-wide changes in water properties such as temperature by transmitting and receiving low frequency sound signals.
photic zone The thin film of lighted water at the top of the world ocean. The photic zone rarely extends deeper than 200 meters (660 feet). Compare euphotic zone: The upper layer of the photic zone in which net photosynthetic gain occurs. Part of the photic zone, which is the thin film of lighted water at the top of the world ocean.
plankton bloom A sudden increase in the number of phytoplankton cells in a volume of water.
baleen The interleaved, hard, fibrous, hornlike filters within the mouth of baleen whales.
land breeze Movement of air offshore as marine air heats and rises.
Arctic Convergence Convergence zone between Arctic Water and Subarctic Surface Water.
benthic zone The zone of the ocean bottom. See also pelagic zone.
bathythermograph A device developed by Athelstan Spilhaus in 1938 to measure temperature/depth profiles in the ocean. Replaced the oceanograph.
ATP Adenosine triphosphate, the compound that acts as the immediate source of energy for all life on Earth. The energy stored in ATP is provided directly by photosynthesis or by respiration of glucose.
animal A multicellular organism unable to synthesize its own food and often capable of movement.
earth sphere depth Uniform depth of earth below the present mean sea level, if the solid earth surface were smoothed off evenly (2440 m).
biological resource A living animal or plant collected for human use. Also called a living resource.
hydrologic cycle Movement of water among the land, oceans, and atmosphere due to vertical and horizontal transport, evaporation, and precipitation.
barotropic Descriptive of a hypothetical atmosphere or ocean in which surfaces of pressure (isobaric surfaces) and density (isentropic surfaces) coincide at all levels, as compared to baroclinic. In a state of barotropic stratification, no potential energy is available for conversion to kinetic energy.
prime meridian Meridian of 0° longitude, used as the origin for measurements of longitude; internationally accepted as the meridian of the Royal Naval Observatory, Greenwich, England.
osmosis The diffusion of water from a region of high water concentration to a region of lower water concentration through a semipermeable membrane.
polar cell The atmospheric circulation cell centered over each pole.
ice cap Permanent cover of ice. Formally limited to ice atop land, but informally applied also to floating ice in the Arctic Ocean.
copepod Small, shrimplike member of the zooplankton; in the class Crustacea.
barycenter Center of mass and center rotation of the Earth-moon system, 1,700 kilometers inside Earth.
polar regions The cold zones between the poles and either the Arctic or Antarctic circles.
reef coast A secondary coast formed by reef-building corals in tropical waters.
calorie The amount of heat needed to raise the temperatures of 1 gram (0.035 ounce) of pure water by 1°C (1.8°F).
primary forces The forces that induce and maintain water flow in ocean systems: thermal expansion, wind friction, and density differences.
heat A form of energy produced by the random vibration of atoms or molecules.
bathypelagic zone The ocean between 656 and 13,120 feet deep; One of five vertical ecological zones into which the deep sea is sometimes divided. This is the zone starting from 100 to 700 m deep (coinciding with the upper limit of the psychrosphere) at the 10°C isotherm.
heterotroph An organism that derives nourishment from other organisms because it is unable to synthesize its own food molecules.
eddy A circular movement in water produced by flows around obstructions or by interacting currents.
gravity wave A wave with wavelength greater than 1.73 centimeters (0.68 inch), whose restoring forces are gravity and momentum.
beach berm The nearly horizontal portion of a beach formed by the deposition of sediment by receding waves. A beach may have more than one berm.
algae Collective term for nonvascular plants possessing chlorophyll and capable of photosynthesis. Simple plants found as single cells or as seaweeds.
foreshore Sand on the seaward side of the berm, sloping toward the ocean, to the low tide mark.
counterclockwise Rotation around a point in the direction opposite to that in which clock hands move. Also called anticlockwise.
asthenosphere The hot, plastic layer of the upper mantle below the lithosphere, extending some 350 to 650 kilometers below the surface. Convection currents within the asthenosphere power plate tectonics.
antinode Portion of a standing wave with maximum vertical motion.
canyon Undersea feature; a relatively narrow, deep depression with steep sides, the bottom of which generally deepends continuously, developed characteristically on some continental slopes.
carrageenan Substance produced by certain algae that acts as a thickening agent.
bay A recess in the shore or an inlet of a sea between two capes or headlands, not as large as a gulf but larger than a cove.
nanoplankton Very small members of the plankton community. Examples are coccolithophores and silicoflagellates.
moon tide Tide caused by gravitational and inertial interaction of the moon and Earth. Also called lunar tide.
disturbing force The energy that causes a wave to form.
coastal cell The natural sector of a coastline in which sand input and sand outflow are balanced.
electron A tiny negatively charged particle in an atom responsible for chemical bonding.
berm A nearly horizontal accumulation of sediment parallel to shore. Marks the normal limit of sand deposition by wave action.
chromatophore A pigmented skin cell that expands or contracts to affect color change.
conservative constituent An element that occurs in constant proportion in seawater. For example, chlorine, sodium, and magnesium.
gulf Part of the ocean or sea that is partly surrounded by land, usually on three sides. It is usually larger than a bay.
photo cell A device that converts light energy to electrical energy; used to determine solar radiation below the sea surface.
hadal The ocean zone below 19,680 feet.
calcium carbonate compensation depth The depth at which the rate of accumulation of calcareous sediments equals the rate of dissolution of those sediments. Below this depth, sediment contains little or no calcium carbonate.
alveoli A tiny thin-walled capillary rich sack in the lungs where the exchange of oxygen and carbon dioxide take place.
bathyal zone The ocean between about 200 and 4,000 meters deep.
chemosynthesis The synthesis of organic compounds from inorganic compounds using energy stored in inorganic substances such as sulfur, ammonia, and hydrogen. Energy is released when these substances are oxidized by certain organisms.
ascidian The sea squirts- a group of invertebrates that produce a larva with a primitive backbone.
active margin Continental margin near an area of lithospheric plate convergence. Also called Pacific Type Margin.
convergence zone The line along which waters of different density converge. Convergence zones form the boundaries of tropical, sub-tropical, temperate, and polar regions.
degree An arbitrary measure of temperature. One degree Celsius (°C) equals 1.8 degrees Fahrenheit (°F).
desalination The process of removing salt from seawater or brackish water.
Algulhas Current A warm current that carries Indian Ocean water around the southern tip of Africa and into the Atlantic Ocean.
higher low water Higher of the two low waters of any tidal day in a region of mixed tides.
chemosynthesis The synthesis of organic compounds from inorganic compounds using energy stored in inorganic substances such as sulfur, ammonia, and hydrogen. Energy is released when these substances are oxidized by certain organisms.
dynamic equilibrium State in which the sums of all changes are balanced and there is no net charge.
Linnaeus, Carolus Carl von Linné (1707-1778). Swedish 'father' of modern taxonomy.
North Atlantic Deep Water Cold, dense water formed in the Arctic that flows onto the floor of the North Atlantic ocean.
chlorine titration The method developed by Knudsen in 1902 to determine the chlorinity and therefore salinity of a sea water sample.
animal A multicellular organism unable to synthesize its own food and often capable of movement.
cetacea The order of mammals that includes porpoises, dolphins and whales.
passive sonar A device that detects the intensity and direction of underwater sounds.
corer Device that plunges a hollow tube into bottom sediments to extract a vertical sample.
magnetometer A device that measures the amount and direction of residual magnetism in a rock sample.
isotonic Referring to a solution having the same concentration of dissolved substances as the solution that surrounds it.
Chordata The phylum of animals to which tunicates, Amphioxus, fishes, amphibians, reptiles, birds, and mammals belong.
ria coast A primary coast formed when rising sea level, caused by the melting of glaciers and ice sheets following the last ice age, flooded coastal river valleys.
carbon dioxide The most important of the greenhouse gases with an atmospheric concentration of 353 ppm.
continental shelf the shallow, gently sloping edge of a continental landmass where it meets the sea.
bioluminescence The generation of light by living organisms using the enzyme luciferase.
beach face The sloping section of a beach profile below the beach berm which is normally exposed to the action of the wave swash.
Alaska gyre A small Pacific Ocean subpolar surface current gyre that rotates counter-clockwise south of Alaska.
cilia Microscopic, hairlike projections of living cells that beat in coordinated fashion and produce movement.
DSL Deep Scattering Layer: A relatively dense aggregation of fishes, squid, and other mesopelagic organisms capable of reflecting a sonar pulse that resembles a false bottom in the ocean. Its position varies with the time of day.
polychlorinated biphenyls Chlorinated hydrocarbons once widely used to cool and insulate electrical devices and to strengthen wood or concrete. PCBs may be responsible for the changes in and declining fertility of some marine mammals.
divergent evolution Evolutionary radiation of different species from a common ancestor.
bioluminescence Biologically produced light.
climate The long-term average of weather in an area.
biological resource A living animal or plant collected for human use. Also called a living resource.
meteorological tide A tide influenced by the weather. Arrival of a storm surge will alter the estimate of a tide's height or arrival time, as will a strong, steady onshore or offshore wind.
notochord Stiffening structure found at some time in the life cycle of all members of the Phylum Chordata.
air mass A large mass of air with nearly uniform temperature, humidity, and density throughout.
Cape Basin An ocean basin located to the west of South Africa at about 35°S in the South Atlantic Ocean.
physical factor An aspect of the physical environment that affects living organisms, such as light, salinity, or temperature.
Chordata The phylum of animals to which tunicates, Amphioxus, fishes, amphibians, reptiles, birds, and mammals belong.
hydrogen bond Relatively weak bond formed between a partially positive hydrogen atom and a partially negative oxygen, fluorine, or nitrogen atom of an adjacent molecule.
rotary tide Tide that is the result of a standing wave moving around the central node of a basin.
bias The amount by which the average of a set of values departs from a reference value.
adhesion Attachment of water molecules to other substances of hydrogen bonds. Wetting.
food web A group of organisms associated by a complex set of feeding relationships in which the flow of food energy can be followed from primary producers through consumers.
zone Division or province of the ocean with homgeneous characteristics.
celestial navigation The technique of finding one's position on Earth by reference to the apparent position of stars, planets, the moon, and the sun.
breakwater Structure protecting a shore area, harbor, anchorage, or basin from waves; a type of jetty.
gas bladder In multicellular algae, an air-filled structure that assists in floatation.
overturn Sinking of denser water and its replacement by less-dense water from below.
berm A horizontal ridge of sand or shingle running parallel to the shore, at the limit of wave action.
Bransfield Strait A strait located between the northern tip of the Antarctica Peninsula and the South Shetland Islands. 120 km wide and extends 460 km from Clarence Island to Low Island.
set Direction in which the current flows.
Animalia The kingdom to which multicellular heterotrophs belong.
Milky Way The name of our galaxy. Sometimes applied to the field of stars in our home spiral arm, which is correctly called the Orion arm.
photic zone The thin film of lighted water at the top of the world ocean. The photic zone rarely extends deeper than 200 meters (660 feet). See also euphotic zone.
bilateral symmetry Body structure having left and right sides that are approximate mirror images of each other. Examples are crabs and humans. Compare radial symmetry.
calcareous Of or containing calcium carbonate or another, usually insoluble, calcium salt.
cat's-paw Patch of ripples on the water's surface, related to a discrete gust of wind.
storm center Area of origin for surface waves generated by the wind; an intense atmospheric low-pressure system.
monoculture Cultivation of only one species of organism in an aquaculture system.
bucket thermometer A thermometer with an insulated container around the bulb.
inlet A passage giving the ocean access to an enclosed lagoon, harbor, or bay.
destructive interference The subtraction of wave energy as waves interact, producing smaller waves.
pH scale A measure of the acidity or alkalinity of a solution. Numerically, the negative logarithm of the concentration of hydrogen ions in an aqueous solution. A pH of 7 is neutral; lower numbers indicate acidity, and higher numbers indicate alkalinity.
half-life Time required for one-half of all the unstable radioactive nuclei in a sample to decay.
precision depth recorder (PDR) Instrument used to obtain continuous pictorial record of the ocean bottom by timing the returning echoes of sound pulses.
calcareous ooze Ooze composed mostly of the hard remains of organisms containing calcium carbonate.
adaptation An inheritable structural or behavioral modification. A favorable adaptation gives a species an advantage in survival and reproduction. An unfavorable adaptation lessens a species ability to survive and reproduce.
fetch The distance over water in which waves are generated by a wind having a rather constant direction and speed.
bathymetry the measurement and charting of the spatial variation of the ocean depths.
prey An organism consumed by a predator.
Crustacea The class of phylum Arthropoda to which lobsters, shrimp, barnacles, crabs, and copepods belong.
photon The smallest unit of light energy.
abyssal hill Small sediment-covered inactive volcano or intrusion of molten rock less than 200 meters high, thought to be associated with sea-floor spreading. Abyssal hills punctuate the otherwise flat abyssal plain.
fracture zone Area of irregular, seismically inactive topography marking the position of a once-active transform fault.
caballing Mixing of two water masses of identical densities but different temperatures and salinities, such that the resulting mixture is denser than its components.
advection Horizontal or vertical transport of seawater, as by a current.
aphotic zone The part of the ocean where no surface light can penetrate.
Ekman transport Net water transport, the sum of layer movement due to the Ekman spiral. Theoretical Ekman transport in the Northern Hemisphere is 90° to the right of wind direction.
plankton net Conical net of fine nylon or Dacron fabric used to collect plankton.
fully developed sea The theoretical maximum height attainable by ocean waves given wind of a specific strength, duration, and fetch. Longer exposure to wind will not increase the size of the waves.
diatomaceous ooze Sediment made up of more than 30% skeletal remains of diatoms.
parasitism A symbiotic relationship in which one species spends all or part of its life cycle on or within another, using the host species (or food within the host) as a source of nutrients. The most common form of symbiosis.
biomass The mass of living material in a given area or volume of habitat.
photo cell A device that converts light energy to electrical energy; used to determine solar radiation below the sea surface.
abyssal plain Flat, cold, sediment-covered ocean floor between the continental rise and the mid-oceanic ridge at a depth of 3,700 to 5,300 meters. Abyssal plains are more extensive in the Atlantic and Indian Oceans than in the Pacific.
zero velocity surface A reference level at which the horizontal velocities are thought to be practically zero.
kelps Group of large, fast-growing brown seaweeds.
ATP Adenosine triphosphate, the compound that acts as the immediate source of energy for all life on Earth. The energy stored in ATP is provided directly by photosynthesis or by respiration of glucose.
biodiversity The variety of different species within a habitat.
bloom High concentration of phytoplankton in an area, caused by increased reproduction; often produces discoloration of water. See red tide.
estuary A semi-enclosed area of water where fresh and saltwater mix.
cephalopod An advanced group of mollusks that includes the squids, octopuses, and cuttlefishes.
Beaufort scale Scale of wind forces by range of velocity; scale of sea state created by winds of these velocities
breakwater An artificial structure of durable material that interrupts the progress of waves to shore. Harbors are often shielded by breakwater.
corer Device that plunges a hollow tube into bottom sediments to extract a vertical sample.
ebb tide tide period between high and low water; falling tide; the period of the tide between high water and the next low water.
slick Area of smooth surface water.
chlorine titration The method developed by Knudsen in 1902 to determine the chlorinity and therefore salinity of a sea water sample.
reverse osmosis The use of pressure to force water through a semi-permeable membrane, leaving behind any dissolved salts. Used to obtain freshwater from seawater.
barotropic Descriptive of a hypothetical atmosphere or ocean in which surfaces of pressure (isobaric surfaces) and density (isentropic surfaces) coincide at all levels, as compared to baroclinic. In a state of barotropic stratification, no potential energy is available for conversion to kinetic energy.
Beaufort Sea The marginal sea consisting of the waters off the northern coast of Alaska and Canada.
sound shadow zone Area of the ocean into which sound does not penetrate because the density structure of the water refracts the sound waves.
intertidal volume In an ambayment, the volume of water gained or lost owing to the rise and fall of the tide.
fjord A deep, narrow estuary in a valley originally cut by a glacier.
Blade Algal equivalent of a vascular plant's leaf. Also called a frond.
cyclone A weather system with a low-pressure area in the center around which winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Not to be confused with a tornado, a much smaller weather phenomenon associated with sever thunderstorms. Se also extratropical cyclone; tropical cyclone.
wind The mass movement of air.
Animalia The kingdom to which multicellular heterotrophs belong.
mantle The layer of Earth between the crust and the core.
polyna A gap in polar pack ice at which liquid water contacts the atmosphere.
Antarctic Bottom Water The densest ocean water (1.0279 g/cm3), formed primarily in Antarctica's Weddell Sea during Southern Hemisphere winters.
Library of Alexandria The greatest collection of writings in the ancient world, founded in the third century BC by Alexander the Great. Could be considered the first university.
iceberg Large mass of ice floating on the ocean that was formed on or adjacent to land. Tabular icebergs are tablelike or flat; pinnacled icebergs are castellated, or jagged. Southern icebergs are often tablular; northern icebergs are often pinnacled.
wave period The time it takes for successive wave crests to pass a fixed point.
bucket temperature The surface temperature of the ocean as measured by a bucket thermometer.
gas exchange Simultaneous passage, through a semipermeable membrane, of oxygen into an animal and carbon dioxide out of it.
bond An energy relationship that holds two atoms together as a result of changes in their electron distribution.
halocline The zone of the ocean in which salinity increases rapidly with depth. See also pycnocline.
abyssal storm Storm-like occurrences of rapid current movement affecting the deep ocean floor. They are believed to be caused by warm- and cold-core eddies of surface currents.
hypocenter See focus
colligative properties Those characteristics of a solution that differ from those of pure water because of material held in solution.
continental shelf the shallow, gently sloping edge of a continental landmass where it meets the sea.
aseimic ridge see transverse ridge
alkaline Basic. See also base.