They dig burrows in the mud that are 1/2 inch wide up to a foot deep. These may hook up with other tunnels and have more than one entrance. These burrows provide a quick escape from predators like fish, raccoons, and water birds. Most fiddlers look for food at low tide and stay near their burrows. If they are too far away when danger comes, they will jump into any burrow to escape.
Burrows provide a place for the crabs to stay during high tide. Fiddlers often roll up a ball of mud and use it to plug the hole of their burrow during high tide. When the water covers their burrow, a tiny pocket of air is trapped inside for them to breath.
All crabs have gills, but crabs that live on land, like the fiddlers, breathe air instead of water.
Their gills must stay wet to work, so they must stay near water at all times.