Dendraster excentricus

 

 

Kingdom:  Animalia

Class:  Echinoidea

Order:  Clypeasteroidea

Family:  Dendrasteidae

Genus:  Dendraster

Species:  excentricus

 

Common Name:  Eccentric Sand Dollar because of the “star” that’s off center on its surface.

 

Morphology:  Disk-shaped with a cone appearance when lying flat.  Light gray, brown, to dark purple; covered by fine tube feet; and the mouth is on the lower surface.

 

Size: Up to 75 mm wide (when laying flat, it can be up to 6 mm high).

 

Range: Baja, California to Alaska.                                           

 

Habitat:  Low intertidal zone or on sandy beaches.  Often just the tests (i.e. hard external covering) of dead sand dollars are found laying on the shores of the Puget Sound, WA and are mistaken for live ones.

 

Diet:  When lying flat or moving through the sand, it feeds on diatoms and detritus that fall onto the surface of the sand dollar.  Contains specialized tube feet, spines, mucus secreting glands, and pedicellariae that are involved in suspension feeding while standing vertical.

 

Predators:  Sea stars, crabs and fish.

 

Links:

http://www.oceanlight.com/lightbox.php?sp=Dendraster_excentricus

http://www.divebums.com/FishID/Pages/sand_dollar.html

http://www.tropicabelize.com/Crab%20Collection/Crabs%20Photos/Legend%20of%20the%20Sand%20Dollar.htm

 

Reference:

 Jangoux, Michel and John M. Lawrence.  1983.  Echinoderm Studies.  Rodderdam: A. A. Balkema.

 

This page prepared by Abbie Moyer, Spring 2004