Although they are occasionally cannibalistic, the majority of the fiddler crab diet consists of detritus, bacteria and algae on and in the sediments (Genoni 1985, 1991; Gosner 1978). The small claws transfer sediment to the mouthparts, where food is separated from sand and other unwanted particles. Food is swallowed and the mouthparts roll the remaining sand into tiny balls that are placed back on the ground. These balls are much smaller than those created during the excavation of burrows (Ruppert & Fox 1988). Mouthparts in many fiddlers are specialized for a specific size range of sediment particles, and this adaptation is partly responsible for the habitat and distribution of species. The mudflat fiddler is commonly found in medium sand, where it uses spoon-shaped bristles, called setae, to clean adhered detritus and other particles from single grains of sand (Bezerra et al. 2006, Maitland 1990, Miller 1961). Crabs also wander while feeding and some species move as far as 50 m away from their burrows (Ruppert & Fox 1988). Studies on feeding behaviors in U. rapax document foraging excursions up to 2 m from the burrow, and crabs have advanced homing abilities that allow them to find their burrows regardless of orientation or obstacles (Layne et al. 2003).Predators: Predators of fiddler crabs include: birds, fishes, turtles, and mammals such as otters and raccoons (Colby & Fonseca 1984, Crane 1975, Ruppert & Fox 1988), in addition to being occasionally cannibalized by other fiddlers (Gosner 1978). Crabs reduce predation risk by fleeing into their burrows or hiding between marsh grasses and mangrove roots. Larvae of Uca spp. are preyed upon by a variety of pelagic and benthic organisms, and are cannibalized by adult fiddler crabs in captive populations (O'Connor 1990).Parasites: Crustaceans are commonly hosts to a variety of parasitic organisms. Parasites that infect U. rapax include trematodes such as: Probolocoryphe lanceolata in the hepatopancreas , Maritrema prosthometra in the thoracic musculature, and Gynaecotyla adunca in the antennal gland (Smith et al. 2007). Mudflat fiddlers are also infected by the larvae of the spiny-headed acanthocephalan worm Arhythmorhynchus frassoni, which usually complete their life cycle as endoparasites in the digestive tract of vertebrates (Nickol et al. 2002).
No one has provided updates yet.