Fiddler Crab - The most distinctive feature of the fiddler crab is the extreme size difference between the two claws on the male. The male waves the enlarged claw back and forth rapidly when attempting to impress a female. The female selects her mate based on not only the size of the claw but also on his “fiddling” display. Fascinating to watch when waving the claws back and forth. Ludo Quinta Do Lago Portugal.