Shrimps Crabs and Lobsters: Decapoda

Physical characteristics: The carapace of adult sand fiddler crabs are about 1 inch (26 millimeters) wide. The eyestalks are very long and slender. The claws of males are distinctly unequal in size, while those of females are smaller and equal in size.

Geographic range: This species is found along the eastern coast of the United States, from Cape Cod, Massachusetts, south to Pensacola, Florida.

Habitat: Sand fiddler crabs live on sandy beaches that open to the sea or on sand-mud beaches in protected areas along salt marsh edges and tidal creek banks.

Sand fiddler crabs live on sandy beaches that open to the sea or on sand-mud beaches in protected areas along salt marsh edges and tidal creek banks. (David & Hayes Norris/Photo Researchers, Inc.)

Diet: They eat bits of plants, bacteria, and other organisms.

Behavior and reproduction: Sand fiddler crabs feed at low tide, scraping up mud with their claws and pulling out bits of food with their mouth parts. Males only use their small claw to feed, while females use both claws. They dig and live in simple burrows in the sand and come out only at low tide to feed. When the tide starts to come in, they will plug the burrow entrance overhead with sand.

Males sit near the entrances of their burrows, where mating occurs, waving their large claw and beating it against the sand to attract females. The female remains in the burrow for about two weeks, until the eggs are about ready to hatch. The larvae do not resemble the adults, and are released into the water at night during high tide and carried away by the current. After six to eight weeks and five molts, the larvae return and settle on the bottom.

Sand fiddler crabs and people: They are occasionally sold as pets.

Conservation status: The World Conservation Union (IUCN) does not consider this species to be threatened or endangered. ∎