A female Mole Crab with eggs.
Emerita talpoida Say, 1817
Mole Crabs (also called Beach Fleas, Sand Bugs, Sand Crabs, and Sand Fiddlers) are categorized as a type of Anomura crab, as are Hermit Crabs and Porcelain Crabs. The world “Anomura” means “irregular tail.” Mole Crabs really do not look a lot like the typical crab because Mole Crabs have very short legs, and some species of Mole Crabs do not even have pincers. They do have a posterior triangular telson. That “backend” and the short legs are adapted for digging downward and backwards into the sand.
The Mole Crab has a somewhat egg-shaped body, and its abdomen is folded beneath its thorax. The legs are usually folded under the body. (The animal looks a bit like the terrestrial isopod known as the Pill Bug or Woodlice.) Female Mole Crabs are about 1-2 inches long; the males are about half that size. The creatures, like typical crabs, have eyes on the ends of moveable stalks.
There are various species of this burrowing creature. Those species most likely to be seen on Carolina beaches are beige-gray-pinkish in color. In warm weather Mole Crabs, along with Coquina Crabs, are one of the most commonly found species in the intertidal zone (the area between the high and low water marks on the beach). In the winter Mole Crabs go out to burrow in the sandy bottom of deeper waters.
The way Mole Crabs eat is by burrowing backwards into the sand in the swash zone, facing the ocean. They hold their antennae above the surface of the sand. As the waves pass over the antennae, the antennae filter food particules (algae and plankton) from it. When a wave washes over a burrowed Mole Crab, he is exposed, so he very quickly burries himself again in order to avoid being swept out to sea, or being eaten by predators.
The sandy color of Mole Crabs also helps to camouflage them, and their hard “shell” or carapace further dissuades enemies. Creatures which hope to eat Mole Crabs include various shorebirds (such as Willets, Sanderlings, and Gulls), Blue Crabs, Ghost Crabs, and some fish. The orange eggs found on a female Mole Crab's underside at certain times make the crabs especially appealing and appetizing to fish.
Surf fishermen often use a sieve-basket in hopes of scooping up Mole Crab-laden sand at the surf's edge. If a fisherman scoops in a favorable location, one or two scoops may yield enough bait for an entire day's fishing. The Mole Crabs are considered good bait for Pompano, Red Drum, Sheepshead, and Kingfish (Whiting).
Some people even eat Mole Crabs, though hundreds must be gathered to make a meal. The Mole Crabs are steamed to make a broth which can be used as a base for chowder.
Incidentally, you can pick up the “kinda cute” Mole Crab. It won't pinch you, since some species, as mentioned, have no pincers, and other species have rather harmless subchelate pincers. (The only “local” Mole Crab with chelate pincers is Euceramus proelongus, which inhabits shallow, quiet water, and is not often seen.)
One more interesting fact: Besides filtering out its nourishment with its two anntena, the Mole Crab uses the feathery appendages to clean itself.