Physical 

Fiddler crabs have a short carapace length; the maximum is 3.8 cm. The carapace is in the shape of a square. Males possess one enlarged claw that can be on the right or left side. Females have two normal sized claws.

Habitat

U. species inhabit mud, sand, marshes, and brackish water areas; any place where tides change to cover their burrows.

Feeding 

U. species use specialized appendages to pass mud and sediment through their mouths. Organic material is filtered out and inorganic material is rejected.