How will the female fiddler crab pick a mate? By the quality of his lodging, the allure of his wave—and, especially, the size of his claw. The female fiddler crab has two small, symmetrical ...

And fiddler crabs, whose charismatic males have oversized claws to attract mates and defend against rivals, are marching up the Eastern Seaboard. This rapid migration is due, in part, to their young.

Male and female fiddler crabs are easily distinguished by looking at their claws. The females have small claws while the ...