It prefers muddy habitats, and digs its burrow above the high-tide line, then creates a mud ledge to shade the entrance to its burrow. Marsh or mud fiddler. Uca pugnax also is a widespread species but is not as tolerant of low salinities as the red-jointed fiddler. Sand fiddler, or Uca pugilator. This is a fairly small species that prefers sandy habitats and does not generally survive in silty mud.
Fiddlers are very active during daylight hours, foraging, mating and digging burrows.
At low tide they emerge from their burrows and roam over the flats in search of algae or decaying vegetation. Females have the advantage when it comes to finding and eating food, because both their claws are small and dexterous. Unlike other crabs, which use their claws or chelipeds to crush food or to grasp objects, the fiddlers' claws are used to pick up sediment, which they scrape with their mouths for food particles derived from organic matter and unicellular plants. The small claws help the females sift through the sediment, which they then redeposit on the ground in the form of pellets after removing nutrients. Fiddlers often eat in a puddle of water to help separate the food from the sediment.