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Echinoderms Characteristics

• Kingdom: Animalia • : Echinodermata . Means “spiny skinned” . Spines are part of the , not the skin! • Radially symmetrical as adults • All live in marine habitat • Eat shellfish, dead plants/ & The

• Simple nervous system (no brain/ganglia) • Nerve ring: circle of nerve fibers around the mouth of an • Radial Nerve: runs from the nerve ring to the tip of each arm in sea stars, controlling the arm • Simple eye: located at the end of each arm, it only senses light • The rest of the body is covered with cells that sense changes/chemicals in the water Nervous System (con’t)

Simple Eye

• A system of canals filled with fluid. • Uses water pumps to help : . move, . eat, . breathe, and . sense its environment

** It’s like hydraulics! And only have it. Water Vascular System Kinds of Echinoderms

5 Classes: 1. Brittle Stars & Basket Stars 2. Sea Urchins & Sand Dollars 3. Sea Lilies & Feather Stars 4. Sea Cucumbers 5. Sea Stars (“starfish”) Brittle Stars & Basket Stars

• Look like sea stars, but have long, slim arms • Often smaller than sea stars • No suckers on their • Move more than other echinoderms Sea Urchins & Sand Dollars

• Round • Endoskeleton forms a solid, shell-like structure • No arms, but use tube feet to move • Sea urchins eat algae with special teeth • Sand dollars burrow in the mud and eat food they find there • Named for their coin-like shape Sea Lilies & Feather Stars

• 5-200 feathery arms • Arms trap food • Sea lilies have a stalk, while feather stars do not • Like sea stars, brittle stars & basket stars, feather stars can re-grow lost arms. Sea Cucumbers

• No arms • Soft, leathery body • Long worm-like shape (unique!) • Move with tube feet Starfish

• 5 planes of • Eat by pushing their cardiac out through their mouth, and then retracting it. The food moves into the pyloric stomach where digestive glands secrete to speed up digestion. • Endoskeleton made up of tiny calcium plates called ossicles. Starfish Anatomy