Transcript Echinoderms

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