2 Echinoderms 6000 living species 20,000 extinct species all oceans, all depthsPlanktonic larvae - bilateral symmetryadult - pentamerous radial symmetrysexual external fertilizationlack a head therefore have oral & aboral surfacesendoskeletonwater vascular system *** only in echinoderms***tube feet and ampullaemadreporite
3 vocabulary Water vascular system - network of water filled canals tube feet - muscular sacs that extend outside the body opposite ampullae. Used for attachment and locomotionmadreporite - a porous plate on the aboral surface, connects water vascular system to the exterior
5 Asteroidea Previous Slide Usually 5 arms, up to 50 arms Ambulacral groove - radiating channels on each arm, has hundreds of tube feetPedicellariae - minute pincher like organs that help keep surface cleanWhat do they eat? Snails, barnacles, bivalve, etc.How do they eat? Project their stomach into soft body of prey, partial external digestionEX. Sea Stars or StarfishPrevious Slide
6 Ophiuroidea 2,000 species What do they eat? Organic material Arms are long thin and very flexible.Arms lack suckers on tube feet. They are not used for locomotion but for feeding and sensory.EX. Basket stars, Brittle stars and sea serpentsPrevious Slide
7 Echinoidea Previous Slide Rigid test with movable spines and pedicellariaeArms moved up to meet at the topNow ambulacral grooves extend from top to bottomWhat do they eat? Plant material, encrusting animals, dead organic matterAristotle’s lantern - jaws and musclesEX sea urchins and sand dollarsPrevious Slide
8 Holothuroidea Elongated body symmetry Endoskeleton: microscopic calcareous spicules throughout watery skin5 rows of tube feet from mouth to anusEvisceration - sudden expulsion of gut and other internal organsEX. Sea cucumbersPrevious Slide
9 Crinoidea 600 species 5 to 200 arms Mouth is located on the ventral surfacemucusfilter feedersEX. Sea lilies, Feather starsPrevious Slide
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