Echinoderms (Phylum Echinodermata, from the Greek for spiny skin) are a phylum of marine animals found at all depths. This phylum appeared in the early Cambrian Period and contains about 7,000 living species and 13,000 extinct ones. Five or six classes (six counting Concentricycloidea) are alive today:

• Asteroidea (asteroids, starfish, or sea stars): about 1,500 species that capture prey for their own food.
• Concentricycloidea (sea daisies), notable for their unique water vascular system; two species; recently merged into Asteroidea.
• Crinoidea (crinoids, feather stars or sea lilies): about 600 species that are suspension feeders.
• Echinoidea (echinoids, sea urchins and sand dollars): notable for their movable spines; about 1,000 species.
• Holothuroidea (sea cucumbers): elongated animals resembling slugs; about 1,000 species.
• Ophiuroidea (brittle stars and basket stars), the physically largest of echinoderms; about 1,500 species.

Extinct forms known from fossils include blastoids, edrioasteroids, and several early Cambrian animals such as Helicoplacus, carpoids, Homalozoa, and possibly machaerids.

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RT @GoBlueToo: From Nature:Sea stars suck up carbon. Much more carbon is sequestered by echinoderms than previously thought.http://tinyu ...
AnnikaCurios (Annika Bergman) Thu, 07 Jan 2010 14:35:52 -0000
RT @GoBlueToo: From Nature:Sea stars suck up carbon. Much more carbon is sequestered by echinoderms than previously thought.http://tinyu ...
From Nature:Sea stars suck up carbon. Much more carbon is sequestered by echinoderms than previously thought.http://tinyurl.com/yg8zfvy
GOBlueToo (Go Blue Too) Thu, 07 Jan 2010 14:24:27 -0000
From Nature:Sea stars suck up carbon. Much more carbon is sequestered by echinoderms than previously thought.http://tinyurl.com/yg8zfvy
says arthropods,echinoderms!!!這兩個字已經煩死人了好不好！還有一堆生字咧，我的天！:( http://plurk.com/p/3a0o4c
mandy92126 (Mandy Li) Thu, 07 Jan 2010 13:41:49 -0000
says arthropods,echinoderms!!!這兩個字已經煩死人了好不好！還有一堆生字咧，我的天！:( http://plurk.com/p/3a0o4c
Learning about echinoderms - they can regenerate parts, use hydrostatic propulsion have pentamic symmetry.cool! !
briggsolhx (Susan Tremainesjg) Sun, 03 Jan 2010 16:48:57 -0000
Learning about echinoderms - they can regenerate parts, use hydrostatic propulsion have pentamic symmetry.cool! !
Finally writing, and I just found a great way to use "cephalopods" and "echinoderms" in the same sentence. NINJAWORLD is gonna rock. ^_^
Zoe_E_W (Zoe Whitten) Sat, 02 Jan 2010 23:12:30 -0000
Finally writing, and I just found a great way to use "cephalopods" and "echinoderms" in the same sentence. NINJAWORLD is gonna rock. ^_^
having a fosters, thinking about echinoderms and arthropods
jimwiese_jd (Jakob Domke) Thu, 31 Dec 2009 01:58:13 -0000
having a fosters, thinking about echinoderms and arthropods

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