1. Echinoderms
Sea stars, sea urchins, and sea cucumbers belong to phylum Echinodermata (“spiny skin”, “hedgehog skin”)
Exclusively marine
Adult echinoderms possess pentamerous symmetry; in which the body is arranged in five parts around a central axis
No dorsal, ventral, anterior or posterior end; oral and aboral ends only

2. Phylum Echinodermata
Echinoderms have an internal skeleton, or endoskeleton covered by a bumpy, sometimes spiny, tissue layer
Echinoderms have a network of water-filled canals connected to muscular tube feet, which extend when filled with water
The vascular system connects to the outside environment via the madreporite on the aboral surface
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3. Phylum Echinodermata

4. Sea urchins have a round, rigid test
Types of Echinoderms
Sea stars can regenerate missing body parts
Brittle stars have long, flexible arms; most abundant group of Echinoderms
Sea urchins have a round, rigid test

5. Sea Urchin (class Echinoidea)

6. Types of Echinoderms
Sea cucumbers are worm-like; elongated along the oral-aboral axis, as if pulled/stretched from the mouth and anus
Branching of initial five arms into many, up to 200; mouth pointed upward
Sea cucumbers can expel the gut and other internal organs via evisceration, through the mouth or anus; distracts predators?
Crinoids use outstretched, feathery arms to capture food particles from the water; includes feather stars and sea lilies