Meet the Flame-backed Fiddler CrabArticle | Updated 6 years ago Flame-backed Fiddler Crab Clay Bryce The Flame-backed Fiddler Crab, or Uca flammula, is also called the Darwin red-legs. Flame-backed Fiddler Crab Image copyright WA Museum Appearance This harmless crab can grow up to 3.5 cm (carapace width). It has a black carapace, and brilliant orange-red claws, one of which is larger in males. They live no more than two years. Food! This Fiddler Crab is a detritivore, probing sediment in search of organic matter. Habitat The Flame-backed Fiddler Crab can be found in an area stretching from Mangrove Bay in Western Australia and north into the Northern Territory. They inhabit sand or sandy mud, and are often found at the edge of mangroves. Breeding and Behaviour Adult males have one small claw and one very large claw, which they use during courtship and combat. This is where the Fiddler Crab gets its name – when this big claw is being waved around, it looks as if the male crab is playing a fiddle.