Chapt13_LifeontheOcean

Chapt13_LifeontheOcean - Life on the Ocean Life on the...

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Unformatted text preview: Life on the Ocean Life on the Ocean Chapter 13 s 1. 2. 2. 3. 3. The marine environment is a hard The ecosystem to study for several reasons: reasons: iit's hard to get to; t's cruise down in a deep-sea cruise submersible Are expensive to build, and to operate. s s s s iit's hard to get your samples back to the lab in t's one piece; Animals are built to withstand the huge Animals pressures of great water depths, When they are brought to the surface they When blow up. blow The whole system is permeated with The hydrogen sulfide, which is the smell of rotten eggs eggs s We can define each part of the ocean on the We basis of the following characteristics: basis 1. 2. 3. 4. 5. 6. 7. temperature amount of light currents salinity nutrient supply water depth nature of the sediment on the bottom TEMPERATURE TEMPERATURE s s s s s The most important, for all organisms, not just the coral. Most oceanic organisms are cold-blooded Most (poikilothermic). they cannot regulate their internal temp. they Their body temperature is near the Their temperature of the water they live in. Animals that can maintain a warmer-thansurroundings internal temperature are surroundings homeothermic. homeothermic s s s Only organisms that Only left the sea for land or freshwater and returned to the sea are homeothermic: Marine mammals Big fish like marlin, Big tuna, and tarpon are homeothermic. homeothermic. METABOLISM METABOLISM s s s The process by which all organisms extract The energy from food, is a chemical reaction that is strongly influenced by temperature. The warmer the temperature, the faster The metabolism will be. metabolism Organisms that normally live in cooler waters Organisms may burn themselves up if taken to warmer water. s s And organisms that normally live in warm And waters won't have enough energy to power their vital organs, like the brain and heart, if they move to cooler waters. Organisms living in warmer waters tend to Organisms grow faster, have a faster heartbeat, reproduce more rapidly, swim more swiftly, and live shorter lives than those living in cooler waters. cooler Remember, AMOUNT OF DISSOLVED GAS in the ocean is also determined by temperature. s Fast swimmers such as salmon, trout, Fast and pike need to live in cold waters because their oxygen demand is high. s AMOUNT OF LIGHT AMOUNT s s s s s Determines how productive plants can be. Determines determined by water depth and water determined water turbidity (how much sediment is suspended turbidity in the water). Light is composed of different colors and Light most light penetrates only about 100 m into the water, less if there is much suspended sediment in ess the water the Blue light can penetrate deepest, to about Blue 450 m. s s Green light can Green penetrate to about 300 m water depth, but plants do not use green light-they reflect green light. reflect This is why plants This look green to us. The depth to which light can penetrate The defines an important area to plants: the PHOTIC ZONE. PHOTIC s Plants have enough light to Plants photosynthesize in the photic zone. s They can't photosynthesize in deeper They water. water. s CURRENTS CURRENTS determines how successful filterfeeders can be. s They need some current to bring food They particles their way, but not so much current that it just blows the food past. s Currents can drag plankton along to Currents colder or warmer waters than the plankton prefer. s SALINITY SALINITY s s s We are all composed of cells that are We surrounded by a membrane. membrane That membrane can allow water to pass That through it readily, but not salt. An organism's body fluids must be the same An salinity as seawater, or the organism needs to exert energy to either keep water in its body, or keep water out. body, s The process The whereby water moves across the membrane but salt doesn't is called OSMOSIS (fig. 13.15-16) 13.15-16) If an organism is less salty than If less seawater, water from the organism's body moves out (to increase its salinity). salinity). s The organism will dehydrate if it doesn't The dehydrate actively drink water and get rid of excess salt that comes from drinking seawater. seawater. s If an organism is more salty than If more seawater, water from the ocean moves into the organism's body and it blows up. up s For higher marine organisms, such as For the arthropods and chordates, the problem is the former: we are slightly less salty than seawater. less s A marine fish marine Its salinity is only 18 Its parts per thousand. s It loses water by It osmosis to increase its salinity, but gains it by drinking. it s However, seawater However, is too salty for it, so it secretes salt via the gills, and produces hardly any urine. s A fresh water fish fresh Its salinity is higher Its than the environment. s It gains water by It osmosis decreasing its salinity, avoids drinking water. drinking s However, fresh water However, moves in, so it produces copious urine. s NUTRIENT SUPPLY NUTRIENT s s s s Determines how abundant life can be. Determines iinclude organic compounds such as nclude organic proteins, vitamins, and inorganic inorganic compounds, called 'minerals', such as calcium, magnesium, selenium, etc. Nutrients for plants are all inorganic and Nutrients plants all include nitrogen, phosphorus, potassium, and a host of others. The nutrient supply to plants is the more The important. Without plants, there can be no nutrients for the animals. s 1. 1. 2. 2. Nutrients for plants come from one of Nutrients two places: runoff from continents products of runoff chemical weathering. upwelling from the sea floor. s 1. 2. Where upwelling occurs? occurs? divergent ocean divergent currents currents eastern boundary eastern currents currents WATER DEPTH WATER s s s determines the amount of pressure an determines amount organism experiences and the amount of light it has. light Water depth defines ocean provinces. Water ocean A province is an area where we expect to find province similar plants and animals, depending on other environmental factors (temperature, current, salinity, nutrient supply)(f.13.19) current, s Provinces have different names Provinces depending on whether we are considering benthonic organisms or nektonic and planktonic organisms. s Pelagic Provinces – (nekton, plankton) s Benthic Provinces – epipelagic 0-200 m – littoral intertidal (foreshore) intertidal – mesopelagic 200-1000 m – sublittoral 0-200 m (continental shelf) – bathypelagic 1000-4000 m – bathyal 200-4000 m (continental slope and rise; mid-ocean ridges) rise; – abyssopelagic 4000-6000 m – abyssal 4000-6000 m (abyssal plains) – hadalpelagic >6,000 m – hadal >6,000 m (trenches) s s s s Most plankton live in the epipelagic, photic Most zone. zone. Most light penetrates into the epipelagic and Most littoral to sublittoral zones. Some whales and giant squid live in the Some mesopelagic and even into the top of the bathypelagic province. We still have so much to learn about life in We the meso-, bathy- and abyssopelagic realms! the Nature of the bottom Nature sediment (sandy, muddy, carbonate), or sediment rocky. Particularly important to the benthos. benthos. s All of the physical factors interplay. s If the sun warms up water at the If equator, water may evaporate from the ocean and raise the salinity. s s Dissolved oxygen levels will go down, Dissolved but plant growth will speed up which can raise oxygen levels back up during the day, but drive them down again at night. s s s s All the physical factors together make up a All province. province Each province of the ocean then has a Each unique set of plants and animals that are adapted to that province. The set of plants and animals is a The community. community A community is all of the organisms living in community the same environment (province) and interacting with one another. interacting s In the ocean, we see that animals and In plants fit into one of four basic lifestyles: lifestyles 1. 2. 3. 4. planktonic nektonic nekto-benthonic benthonic Each community has its share of Each community plankton, nekton, and benthos. s The really defining members of most The communities would be the BENTHOS communities BENTHOS because some nektonic organisms can swim into an area and swim out of it again. s s So a particular community exists because it So community shares the following characteristics: • physical characteristics of the water water s s s s s s temperature amount of light vigor of the currents salinity nutrient supply water depth • characteristics of the sea floor the benthos live on characteristics sea or in (sandy, muddy, rocky, carbonate) and • the types of animals and plants within each. the animals plants ...
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This note was uploaded on 09/24/2011 for the course OCE 1001 taught by Professor Staff during the Spring '11 term at Broward College.

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