Photo by Robert Webster
Latin Name: Uca pugilator
Species: Marine Invertebrate
Conservation Status: Not Evaluated
Sand fiddler crabs have a square carapace (back) that ranges in colors from purple, gray, brown, and white with a H-shaped marking. Their carapace can reach 1.4 inches long. Males have one large claw and one small claw, while females have two small claws. When males lose a large claw, their remaining claw grows to become larger and the lost claw is replaced with a small one.
Range & Habitat (map)
These crabs live in salt marshes along the coast from Massachusetts to Florida.
Diet
Sand fiddlers feed on detritus, decaying plants and organisms, algae, and bacteria. When feeding, the crabs separate food from the mud/sand and roll the sand into small balls that you may find throughout the salt marsh. Males are not as efficient as females because their large claw hinders this sorting process.
Life History
Sand fiddler crabs breed throughout most of the summer. This is when the male’s large claw finally comes in handy, as it is primarily used for attracting a mate. They wave their claws back and forth to attract a female, giving the appearance of a violin and earning them their name. Females release their eggs into the water after incubating the egg sponge for two weeks.
Significance
Fiddler Crabs live in large colonies and are a major food source for many animals in the salt marsh, including birds, terrapins, blue crabs, raccoons, and more. These crabs will dig burrows as deep as 2 feet, which adds oxygen to the marsh and helps with nutrient turnover, which aids the growth of marsh grasses.
Threats & How You Can Help
While these crabs are currently considered common and abundant, the reduction of salt marsh habitat threatens these populations. If you see these crabs while in the marsh, be careful handling them as they can easily lose their claws, which limits their ability to feed, protect their territory, and attract mates until a new claw grows back.