Sunday, December 12, 2010

Fiddler Crab (Uca Rapax) By Dylan Burchett

I. Introduction

Fiddler Crabs, also known as Calling Crabs, are of the Uca genus and arthropoda phylum. Fiddler Crabs are semi-terrestrial marine crabs known for their asymmetrical claws and live in burrows made in the shores of salt marshes or sandy or muddy beaches.

II. Anatomy

III. Form & Function

Fiddler crabs are most well known for their asymmetrical claws, the larger claw being their defining characteristic. The larger claw has many uses, its main uses being for courtship and fighting. When it comes time to court a female, the male fiddler crab goes through a series of waving motions with its larger claw to attract a female. If the female consents, the two enter the male’s burrow where they will mate. Two weeks later, the female will emerge to release her newly fertilized eggs into the water. The larger claw of the fiddler crab is also used to fight with other fiddler crabs, or for defense. If the larger claw is removed, it will grow back in the next molt. The burrow of the fiddler crab is also instrumental to the success of the creature. The burrow, while often used for mating, is also used as a safe haven from predators, such as egrets, herons, and raccoons, as well as a place to hibernate in the winter. Fiddler crabs are often between 2.5-5 cm in length, and live for 1.5 years. Fiddler crabs feed on detritus, algae, bacteria, and fungus.

IV. Impact on World/Humanity

Fiddler crabs are very important to the marshland ecosystem, as they eat detritus which helps clean up the marsh. The burrows of fiddler crabs are also helpful to the marshland ecosystem, as they create a system of tunnels in the earth that aerate the various grasses of the marsh.

V. Journal Article Review

This article is about how fiddler crabs track their way to and from their burrows. Scientists seem to have many guesses, but no one is quite yet sure how the fiddler crabs do it.

Works Cited

• Marcus, A. (n.d.). How Crabs Find Their Way Back Home. Scientific American. Retrieved December 12, 2010, from
• Fiddler Crabs. (n.d.). Wikipedia. Retrieved December 12, 2010, from
• Fiddler Crab (Uca rapax). (n.d.). Texas Parks and Wildlife. Retrieved December 12, 2010, from

1 comment:

  1. The thumbnail size black crabs that climb in droves over my railroad tie retaining wall eat my vegetable plants! I live on the marsh on Calibougue Sound on Hilton head Island, S.C. How can I discourage them??? Please help.