Echinoderms: Sea stars, Brittle stars, Urchins, and Cucumbers

The Echinoderms are the hedgehogs of the sea. Or at least that is what their name imples. Echinos is Greek for "hedgehog". All of them have spiny skin in one form or another. They also have a very unique water vascular system which allows them to manipulate their thousands of tube feet to move, feed, anchor themselves in position, or capture prey.

The Pacific Northwest has the greatest variety of Echinoderms in the world! How can you recognize one underwater? Look for spiny skin, tube feet, and pentaradial symmetry (divide them into five parts and all slices are equal).

(click on photo to enlarge)
Sea stars
	Vermillion star (Mediaster aequalis)
	Rose star (Crossaster papposus)
	Ochre star (Pisaster ochraceus) These stars are abundant in Northwest waters and can be seen in amazingly large aggregations along the coast. They come in two colors: purple and orange. When spotted, they may look as if they are just hanging out, but as voracious eaters, they are probably dining on a barnacle, mussel, snail, or other prey item.
	Leather star (Dermasterias imbricata) With its mottled blue, orange, and purple coloring and its smooth surface, its hard to mistake this star for any other. Its arms grow up to 6" and t can be seen attached to rocks and pilings at many dive sites. It enjoys dining on our common plumose anemone as well as other echinoderm relatives (cucumbers and urchins).
	Sunflower star (Pycnopodia helianthoides) This is our largest star , which posesses up to 24 arms and grows to a maximum of a 18 inches in diameter. It is also our fastest star, and can cruise along at 6 feet per minute. It can be spotted in a wide range of habitats.
	Morning sun star (Solaster dawsoni)
	Spiny pink star (Pistaster brevispinus) With arms up to 12.5 inches and tube feet that can extend deep into the sand, this is a starfish that bivalves worry about. It has a pinkish color and short spines, and occasionally can be confused with the mottled star, Evasterias troschelii.
	Cushion star (Pteraster tesselatus)
	Wrinkled star (Pteraster militaris)
Brittle stars
	Gray brittle star (Ophiura lutkeni)
	Daisy brittle star (Ophiopholis aculiata)
Sea cucumbers
	California sea cucumber (Parastichopus californicus)
	Salt & pepper sea cucumber (Cucumaria piperata)
	Red sea cucumber (Cucumaria miniata)
	Creeping pedal sea cucumber (Psolus chitonoides)
	White sea cucumber (Eupentatcta quinquesemita)
Sea urchins
	Green sea urchin (Stronglyocentrotus droebachiensis)
	Red sea urchin (Stronglyocentrotus franciscanus) This is probably the most common urchin seen by divers in Northwest waters. Despite its name, often has purple spines, so don't confuse it with the purple sea urchin which has fewer and shorter spines.
	White sea urchin (Stronglyocentrotus pallidus)