What is "fiddler crab"

Fiddler \Fid"dler\, n. [AS. fi[eth]elere.]

1. One who plays on a fiddle or violin.

2. (Zo["o]l.) A burrowing crab of the genus Gelasimus, of many species. The male has one claw very much enlarged, and often holds it in a position similar to that in which a musician holds a fiddle, hence the name; -- called also fiddler crab, calling crab, soldier crab, and fighting crab.

3. (Zo["o]l.) The common European sandpiper ( Tringoides hypoleucus); -- so called because it continually oscillates its body.

   Fiddler crab. (Zo["o]l.) See Fiddler, n., 2.

n. a genus of crab in which the male has one hugely enlarged claw (genus ''Uca'').

n. burrowing crab of American coastal regions having one claw much enlarged in the male

A fiddler crab, sometimes known as a calling crab, may be any of approximately 100 species of semi-terrestrial marine crabs which make up the genus Uca. As members of the family Ocypodidae, fiddler crabs are most closely related to the ghost crabs of the genus Ocypode. This entire group is composed of small crabs – the largest being slightly over two inches across. Fiddler crabs are found along sea beaches and brackish inter-tidal mud flats, lagoons and swamps. Fiddler crabs are most well known for their sexually dimorphic claws; the males’ major claw is much larger than the minor claw while the females’ claws are both the same size.

Like all crabs, fiddler crabs shed their shells as they grow. If they have lost legs or claws during their present growth cycle, a new one will be present when they molt. If the large fiddle claw is lost, males will develop one on the opposite side after their next molt. Newly molted crabs are very vulnerable because of their soft shells. They are reclusive and hide until the new shell hardens.

Fiddler crabs exhibit a constant circadian rhythm in a controlled laboratory setting that mimics the ebb and flow of the tides. The crabs turn dark in the day and light in the dark.