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Unformatted text preview: 14/02/2008 09:07:00 ← Echinodermata • Means spiny skin • Only major invertebrate deuterostome phylum • 7000 species • Exclusively marine, benthic o Didn’t make it in freshwater or on land • Radial symmetry o Penta-radial o Secondarily derived-their larvae are bilateral • Endoskeleton: calcareous plates covered by skin ← ← Class Asteroidea • Sea stars or “sea fish” • 5 or more radial arms • all marine habitats (intertidal or deep sea) • Mostly carnivorous • They have “tube feet” o Water comes in through madreporite, passes through stone canal then the ring canal (only central structure) o Ampullae are like little squeeze bulbs, when contracted they cause the two feet to extend and stick onto things with suckers • They exude their stomachs out of their mouths and onto their prey, stomach excretes digestive enzymes and suck up the nutrients, they pull the stomach...
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- Spring '08
- Water vascular system, Sea urchin, Class Asteroidea Sea, Asteroidea Sea