Hermit crabs are in the Phylum Arthropoda and Class Crustacea. They are usually found scurrying across the ocean floor or hiding under rocks.
Acadian hermit crabs are reddish-brown in color. The crab has a soft abdomen about 1 inch long. Because the abdomen has no exoskeleton, the crab keeps it hidden in a shell. Usually the shells are empty periwinkle, moon snail or whelk shells that the crab has found, although they sometimes compete for shells with other crabs. When the hermit crab outgrows its shell, it needs to find a new one.