Characterized by radial symmetrySeveral arms radiating from a central

bodybody consists of five equal segments,

each containing a duplicate set of various internal organs

no heart, brain, or eyesmouth is situated on the underside

and their anus on topdo not possess an external skeleton.

a thin outermost skin covers a mesodermal endoskeleton made of tiny calcified plates and spines

Echinoderms are exclusively marine

Occur in various habitats intertidal zones, the

bottom of the deep sea trenches, coral reefs, cold and tropical seas

Some are carnivorous, others are detritus foragers, or planktonic feeders

Reproduction is carried out by the release of sperm and eggs into the waterMost species produce

pelagic (free floating) planktonic larvae which feed on plankton

Echinoderms are important both biologically and geologicallyfew other groupings are so

abundant in the biotic desert of the deep sea, as well as the shallower oceans

their ossified skeletons are major contributors to many limestone formations, and can provide valuable clues as to the geological environment.

Sea Starstypically have five "arms" which radiate from

a central diskusually hunt for shelled animals such as

oysters and clamshave two stomachs, one for digestion, and

one can be extended outward to engulf and digest prey

radiate diversely in shapes and colors

Sea Cucumberselongated body and leathery

skinGenerally scavengers,

feeding on debrisCommunicate through

sending hormone signals through the water

body wall can be loosened and tightened at willIf it wants to squeeze

through a small gap it can essentially liquefy its body and pour into the space.

Sea Urchinssmall, spiny, globular

creaturesmove slowly, feeding

mostly on algaelight touch elicits a

prompt and visible reaction from the spines, which converge toward the point that has been touched

Sand Dollars

have a skin of moveable spines

when it is found washed up on the beach, it is dead

has a set of five paired rows of pores that are arranged in a petal-like pattern

CrinoidsAlso known as sea lilies

or feather-starsa mouth on the top

surface that is surrounded by feeding arms

usually have a stem used to attach themselves to a substrate, but many live attached only as juveniles and become free-swimming as adults

Sourceshttp://diybio4beginners.blogspot.com/

2009/03/marine-bio-intro-to-echinoderms.html

http://www.starfish.ch/reef/echinoderms.htmlhttp://en.wikipedia.org/wiki/Starfishhttp://www.oceaninn.com/guides/echino.htmhttp://exploresea.com/?p=36http://store.justinhankins.com