The reason the male fiddler crab has such a big claw is to attract females. Every two weeks during the summer, male fiddler crabs build little round burrows, which are deeper and better than the ones they usually build. The crabs guard these burrows fiercely. Where there are lots of fiddler crabs, there are usually hundreds of these little burrows all lined up only a few inches apart. Each male fiddler crab stands out in front of his burrow waiting for the females to return from eating. The females then walk around looking at the different burrows. As they walk past, the males wave their big chelipeds back and forth. If a female likes a male or burrow, she will stop and stare. Then the male begins waving his cheliped wildly. Sometimes the female will run away. However, if she stays, the male will run between her and the burrow, back and forth, again and again. If she has still not run away, she will come closer to the burrow. Then the male will enter the burrow a little and start drumming against the side of the tunnel with his cheliped. If the female likes what she hears, she will go down into the burrow, and they will mate.