They use former snail shells instead. The snail shell does not grow but the hermit crab does so when it grows it has to find a new shell . What you'll probably see first is the male's large, yellow pincer which has little other use than as a display during courtship. The females have dark pincers of equal size. Fiddler Crabs Walking through the marsh you can't help but notice the fiddler crabs and their abundant burrows.
Fiddler crabs get their name from the male's large claw.
They use the claw to defend their burrows and to attract mates. Males have a highly ritualized combat of arm-waving, bobbing of the body, and standing with an open, upright stance. However compat rarely gets physical as there is too much risk of injury to both crabs. Crab Gallery Crustacean Gallery Choose a group of animals from the pictures below to reach a gallery of related crustaceans. Here you will find information about their biology and classification.