Echinarachnius parma

Echinarachnius (genus) Common Sand Dollar
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Echinoidea
Order:	Clypeasteroida
Suborder:	Scutellina
Family:	Echinarachniidae
Genus:	Echinarachnius Gray, 1825
Species:	E. parma
Binomial name
Echinarachnius parma Lamarck, 1816

The Common Sand Dollar (Echinarachnius parma) is a species of sand dollar native to the Northern Hemisphere. It is circumpolar, and can be found on the North American east coast from New Jersey north, as well as in Alaska, Siberia, British Columbia, and Japan. It inhabits isolated areas on sandy bottoms below the low tide level down to a depth of 5,000 feet (1,500 m).

The tests (shells) of these sand dollars are round, flat and disc-like, typically measuring 3 inches (7.6 cm) in diameter. The entire shell is also covered with maroon-colored moveable spines. Color is a purplish brown, but they become bleached white when washed ashore. As in other echinoderms, five radial furrows branch from the mouth on the animal's underside.

This and other species of Echinarachnius have been around since the Pliocene epoch.

References

• Echinarachnius parma, Animal Diversity Web