Sand crabs, also called mole crabs, live in the constantly shifting sands at the edge of the beach and ocean, called the swash zone. To stay put, this small crab (.75 to 2 inches) burrows backwards as fast as it can. As a wave breaks over it, the crab sticks out its feather-like antennae to catch plankton.
Mole crabs are an important link in the sandy beach food web. They feed on plankton and, in turn, are eaten by many fishes and birds. Along the Pacific coast, there’s a program for students called LiMPETS (Long term Monitoring Program and Experiential Training for Students). In this “Citizen Science” program, students look for and count Pacific mole crabs on sandy beaches as an indicator of the health of the beaches.