Help me identify a Connecticut crab?

Question

I work on a nature preserve, it is a narrow strip of beach: one side is the ocean, the other is a protected bay/cove area. On the quiet side, there are thousands of little crabs that dig burrows into the mud/sand. If I sit still, they will all come up to feed. As soon as I move, they scurry back into their burrows. I think they are ghost crabs, but they have this very distinctive purple spot on their back. They are about 1 -2 inches wide, and one claw is drastically bigger than the other. Is this a ghost crab? the pictures I see online don't really match up.

Answer 1

Your crab is an Atlantic Sand Fiddler Crab, Uca pugilator.

Check out the links below for a description of the animal, it's habitat and range, and some closeup photos.

I am a biologist, formerly lived in CT where I ran the nature center at Sherwood Island State Park for the DEP, and I'm goofy for crustaceans.