Echinoderms

Spiny skin, internal skeleton, water vascular system, and suction cuplike structures called tube feet. Most adults have 5-part radial symmetry.EchinodermsStarfish, Sea Urchins, Sand Dollars, Brittle Stars, Sea Cucumbers, Sea Lilies, Feather Stars

EnvironmentMarine HabitatsHelp control populations of other forms of marine life.Food SourceCarnivorous 5-part jawlike structure to scrape algae from rocksTube feet along their arms to capture floating planktonPushes its stomach out through its mouth, pours out enzymes and digests the mollusk in its own shell

Maintaining Homeostasis - Internal(Circulation, Respiration, Excretion)Most breathe through the thin-walled tissue in their tube feet Others have small outgrowths called skin gills

Circulation through the water vascular system

Nitrogen containing wastes are released out the anusMaintaining Homeostasis - External(Response)Have no head.no nervous system. Just a nerve ring around the mouth and radial nerves that connect the ring with the body sections

MovementDetermined by the structure of the organisms exoskeleton (either spines or tube feet)

ReproductionExternal fertilizationSexes are separate

Evolutionary MilestoneDeuterosomes (the first opening in the embryo becomes the anus during embryonic development) they are the first to have true body cavities.

Picture Fig 28-23 p735

Vocabulary: endoskeleton (734); water vascular system (735)