The name fiddler crab comes from the one enormous claw that the males have, which they hold in front of their body like a fiddle. They can be found in West Africa, the Eastern Pacific, the Western Atlantic and the Indo-Pacific.
Fiddler crabs shed their shells as they grow and if they lose a leg or a claw in their growth cycle a new one will begin to grow when they molt. When they shed their shells they become very vulnerable as their new shell is initially soft and so they will hide until the shell hardens.
Male fiddler crabs produce vibrations and pulses that serve as a sort of morse code to attract females into their burrows to mate. It ha been discovered that this code is surprisingly informative and the females can decipher it to learn more about the male’s size and stamina. The ones able to wave their claws higher and for longer periods of time have more success.