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Phylum Echinodermata Chapter 28.4. Please set up your notebook for Cornell Notes. Echinoderms Characteristics Have endoskeleton, water vascular system, spiny skin, 5 part radial symmetry, tube feet and larva are bilaterally symmetrical Deuterostome. Form and Function
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Phylum EchinodermataChapter 28.4 Please set up your notebook for Cornell Notes
Echinoderms • Characteristics • Have endoskeleton, water vascular system, spiny skin, 5 part radial symmetry, tube feet and larva are bilaterally symmetrical • Deuterostome
Form and Function • Water vascular system fluid-filled, carries out respiration, circulation and movement • Madreporite opening to water vascular system • Connects to a ring canal that forms a circle around the mouth • Ring canal branches out to 5 radial canals • Tube feet attach to radial canal • Works like a suction cup
Feeding • Sea urchins use 5 part jaw-like structures to scrape algae from rocks, or eat kelp • Sea lilies use tube feet to get plankton • Sea cucumbers scavenge on ocean floor • Sea stars open shells of mollusks, insert stomach, release digestive enzymes and suck out remains
Respiration and circulation • Most respiration takes place using water vascular system • Some have small gills • Circulation takes place using water vascular system • Excretion • Digestive wastes exit anus • Ammonia waste diffused through tube feet • Response • Do not have highly developed nervous systems • Some sensory cells • Nerve ring around mouth w/ nerves going down each arm • Movement • Determined by type of endoskeleton • Most use tube feet • Reproduction • External • Larva are free-swimming, bilaterally symmetrical • Adults live on ocean floor, radially symmetrical
Classes of Echinoderms • Class Asteroidea sea stars • Radially symmetrical w/ 5 (or multiples of 5) arms • Mouth and anus together on ventral side • Can regenerate missing parts • Mostly carnivorous
Class Crinoidea feather stars, sea lilies • Radially symmetrical, body is cup shaped w/ feathery arms projecting from central disk • Arms are called pinnules and are covered in sticky substance that catches passing particles (filter feeders) • Mouth and anus on dorsal side
Class Ophiuroidea brittle stars • Radially symmetrical, central body with 5 snake-like arms • No anus, waste eliminated through ventral mouth • Arms break off to get away from predators • Eat mollusks, worms and crustaceans
Class Echinoidea sea urchins and sand dollars • Radially symmetrical w/ spiny (chitinous) skeleton • Mouth with teeth located ventrally • Anus on dorsal side • Move using tube feet and spines • Most grazed on algae but some eat sponges
Class Holothuroidea sea cucumbers • Bilaterally symmetrical, cucumber shaped w/ mouth at one end and anus at the other • Eat sand and digest biological particles in it, then poop it out • Tentacles around mouth are modified tube feet • Tube feet on bottom move them forward • Some species have separate sexes, some are hermaphrodites