Fiddler crabs are capable of scraping food particles off grains of sand. Fiddler crabs turn a dark color during the day and turn a lighter color at night. Most commonly seen crab in a salt marsh. Males have one large claw and one small claw. Both claws of the females are the same size.
Males wave their claws to challenge other males to fight.
During high tide, the fiddler crab packs sand into the entrance to his burrow and waits until the tides goes down again. They are also called invertebrates. If one claw is lost, the fiddler crab will soon regenerate a new one. The Fiddler Crab, Uca rapax , has 5 other cousins in Texas.