The legs and uropods have hairy margins to assist in digging and for use in collecting food and transferring it to the mouth.

[4] The species is common on the beaches of California, but greater changes in population levels occur further north, probably as a result of variations in the coastal currents which in some years passively disperse the planktonic larval stages northwards.

On any particular beach, the distribution of sand crabs from one part to another can vary greatly for reasons not fully understood.

The female lays batches of up to 45,000 eggs each month and carries them about beneath her abdomen tucked under her telson.

[4] The megalopae settle out onto sandy beaches where they moult and develop into juveniles, which mature into adults within a few weeks.

These birds actively patrol the part of the beach washed by incoming waves, probing the softened sand with their bills.

The bird maximizes its chance of feeding on sand crabs by scurrying at the edge of the surf.

[9] Other birds that eat sand crabs include willets, godwits, surf scoters, blackbellied plovers, and curlews.

[2] The barred surfperch (Amphistichus argenteus), found off the coast of California, consumes a large number of sand crabs.

[6] The sand crab has been evaluated as an indicator species for monitoring the level of domoic acid-synthesizing diatoms (Pseudo-nitzschia spp.)