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Lecture12MarineAnimalsIII - Ch 15 Marine Animals Marine •...

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Unformatted text preview: Ch. 15 Marine Animals Marine • Multicellular heterotrophic organisms • Obtain food (ultimately) from primary producers •Problems: Finding food Avoiding predators Finding mates (reproduction) • Use a variety of survival strategies Phylum Echinodermata Phylum Exclusively marine phylum Lack eyes or brains, move slowly Radial symmetry; body plan of 5 sections ( = Radial pentaramous symmetry) pentaramous Includes sea stars, brittle stars, sea urchins & Includes sand dollars, sea cucumbers Classes: Asteroidea are the sea stars, Ophiuroidea are the Brittle Ophiuroidea Stars, the Holothuroidea are the Sea Cucumbers, the Echinoidea Holothuroidea Echinoidea comprise the Sea Urchins and sand dollars and the Crinoidea are Crinoidea the Sea Lilies and Feather Stars. Echinarachnius parma Holothuria floridana Sea star Strongylocentrotus droebachiensis Five part jaws of a sea urchin Note 5 part body plan; arms have spiny projections, delicate tube feet underneath which function as suction cups and can grip objects/ surfaces Sea stars have a water-vascular system (complex of water filled canals and valves and projections used for locomotion); operates like a hydraulic system; can use for movement or feeding (to open a mussel) Sea Cucumbers (Class Holothuroidea) (Class Elongated body and leathery skin (look like a cucumber) Found on the sea floor worldwide Have an endoskeleton (support tissue; made of mesoderm) Have endoskeleton Are generally scavengers, feeding on benthic debris or plankton Are scavengers One way they might get a supply of food is to position themselves in a One current where they can catch food that flow by with their tentacles when they open. Another way is to sift through the bottom sediments using their tentacles. They have the peculiar adaptation of expelling first sticky threads, perhaps to incapacitate predators, and then their internal organs when startled by a potential predator = defensive vomiting!. These organs defensive !. can then be regrown. can a = tentacles b = anus (with cloaca inside) c = ambrulacral feet (tube feet) d = papillae Sea cucumbers extract oxygen from water in a pair of 'lungs' or respiratory 'trees' that branch off the cloaca just cloaca inside the anus, so that they 'breathe' by drawing water in anus so through the anus and then expelling it. through A variety of fishes have evolved a commensalistic variety relationship with sea cucumbers in which the fish will live in sea cucumber's cloaca using it for protection from predation, a source of food (the nutrients passing in and out of the anus from the water), and to develop into their adult stage of life. The largest American species is Holothuria floridana, llives ives Holothuria in lower littoral; sea grass beds (up to 35 cm long) in Holothuria floridana Phylum Chordata Phylum Most advanced animal phylum Includes invertebrates and vertebrates Have possessed a “notochord” (notus = back, chorda = Have “notochord” cord) at some time in their development cord) Is a tubular dorsal nervous system and gill slits behind Is the oral opening the Notochord was critical in evolution; allowed complex allowed embryonic development by providing a frame on which a developing embryo could be constructed as well as an internal mechanical foundation for skeletal and muscle development development Invertebrate Chordates Invertebrate 5% of chordates lose their notochord = the 5% invertebrate chordates E.g. tunicates (sea squirts) or salps tunicates salps Suspension feeders that look like sponges Solitary or colonial, attached or free-living Filter water with a special mucous Filter plankton net, trap a wide variety of particles particles Larvaceans, Salps, and Tunicates Larvaceans, Members of the Phylum Chordata Members Phylum possess a notochord, dorsal nerve cord, possess and pharyngeal gill slits at some point gill Suspension feeders Most begin life in a mobile larval stage Most and remain pelagic (salps, larvaceans), others later develop into a barrel-like adult forms (tunicates), both pelagic & benthic benthic Important contributors to organic Important carbon, marine snow: gill slits secrete extensive mucus nets or webs extensive Larvaceans Larvaceans (sometimes called “Appendicularians”) Builds a new house every day! Oikopleura Oikopleura in its mucus house Salps Salps Salps are filter feeders, Salps continuously filtering water through a mucus net as it swims. swims. Pegea Salpa Chain forming salps – individual forms smaller chained whorls of offspring Cyclosalpa Tunicates- planktonic Thalia Dolioletta solitary stage Dolioletta “nurse” stage Tunicates - benthic Mucous net comes from pharynx, is moved by tiny cilia to esophagus, swallowed Transitioning to the Vertebrate Chordates…. Chordates…. Amphioxus, an invertebrate chordate with some vertebrate features…swims by undulating like fish, has a well developed dorsal tubular nerve cord (similar to spinal cord) Vertebrate Chordates Vertebrate Possess backbones 95% of all chordates are vertebrates We will discuss: “Fishes” (Class Agnatha, Class Chondrichthes, Fishes” Class Osteichthyes) Class Amphibians Marine Reptiles Marine Birds Marine Mammals (“charismatic megafauna”) “Fishes” Live in water, possess gills, fins Ectothermic, take on the temperature of their take surroundings surroundings 40% of species are freshwater, 60% marine 40% (majority of their lives) (majority First fish evolved ~500 million years ago; these First were motile, jawless, digestive tubes were “Age of fishes” 408 to 360 million years ago; Age jawed fishes radiated into a vast number of habitats habitats Class Agnatha Class Includes hagfish and lampreys “a” = lacking, “gnathos” = jaw (so common a” name is??) name No paired appendages/fins Snakelike bodies, pierced with gill slits Snakelike and/or slime glands and/or Sense organs Flattened tail undulates to provide motion Slime glands used for defense Lamprey – have a toothed, funnel-shaped mouth, latch on to fish and suck nourishment; detach before host croaks Class Chondrichthyes Class Sharks, skates, rays Old, sharks have been around twice as Old, long as dinosaurs; today’s version is similar to ancestors similar “chondros” = cartilage, “icthys” = fish Skeleton is made of tough, elastic material Skeleton called cartilage (no true bone) called Have jaws with paired fins Relatively few species Relatively Tend to be larger than Agnathans or bony fishes Nearly all marine Sharks tend to like water column, rays prefer Sharks near bottom near Skates, rays are flattened, pectoral fins are Skates, attached giving them a triangular appearance (or “winged”) “winged”) Glide with a slow, rhythmic flapping of fins Negatively buoyant (no gas bladders) Some have a defensive barb at the base of the Some tail tail Largest rays feed on plankton, smaller species Largest crush mollusks or arthropods with mouth parts crush SHARKS!!!! SHARKS!!!! Find three facts about sharks, shark Find attacks, anything sharky. attacks, Bring them to class next day. ...
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