Echinoderms

Characteristics of Echinoderms  Echinoderms are invertebrates  They have radial symmetry  They have an internal skeleton called an endoskeleton  They have a system of fluid-filled tubes called a water vascular system  THINK! – What does echinoderm mean? “Spiny Skinned”

Movement  An echinoderm has an internal system of tiny fluid- filled tubes.  Portions of these tubes can squeeze together forcing water into structures called tube feet.  The tube feet stick out from the echinoderm’s underside and when filled with water act like suction cups.  This allows the echinoderm to grip the surface of an object and move along slowly.  Video Clip - Echinoderms in a Minute! Check out how they move! Video Clip - Echinoderms in a Minute! Check out how they move!

Activity: Color Coding a Sea Star Stomachanus Digestive glands Ring Canal Water Vascular System Tube feet Use the following key  Anus  Stomach  Digestive Glands  Ring Canal  Water Vascular System  Tube Feet  Spines Spines

Sea Stars  Predators that eat mollusks, crabs, and other echinoderms  A sea star will grasp a clam with all 5 arms and force its stomach out. Digestive juices then break down the clam’s tissue so the sea star can eat.

Brittle Stars  It has long, slender arms with flexible joints.  Brittle stars do not have suction cups.  They move by waving each of their long arms in a snake-like motion against the ocean floor.

Sea Urchins  They have no arms  Movable spines cover their body  To move, bands of tube feet extend out between the spines  They eat their food (seaweed) with 5 teethlike structures protruding from their mouth

Sea Cucumbers  They look like cucumbers  Underneath their leather-like skin their bodies are soft, flexible, and muscular  They use their tube feet to crawl  It uses tentacles around its mouth to feed

Echinoderms Video Clip  Watch this clip closely to see how the tube feet work in movement! Watch this clip closely to see how the tube feet work in movement!