Sand dollar echinoids of the genus Dendraster are arguably among the most common macrobenthic invertebrates of the northeastern Pacific Ocean. It is also described as a type of irregular sea urchin (Superorder Gnathostomata) which displays varying degree of radial symmetry and commonly found across intertidal zone. The body of sand dollar (aboral and oral surface) is covered by short spines that allow this animal to undergo feeding processwhile itsflat shape test helps in the burrowing process into the sediment during low tide.
The most frequently encountered member of the genus, D. excentricus, is known to occur from southern Alaska to southern Baja California in huge numbers almost everywhere there is a suitable shallow water, sandy bottom.
Sand dollars eat microscopic plant and animal life, hunting by shuffling through loose sand. They are preyed on by bottom dwelling fishes, such as flounder.
Sand dollar plays important role in ecological structure. First, sand dollar acts as predator to diatom, algae and detritus, while it becomes prey for fishes, crab and sea stars. Thus it maintains the stability in food chain relationship of the ocean. The second ecological role of sand dollar is as reworking sediments and recycling nutrients in the benthic community at intertidal zone of sandy beach.
Sand dollar
