"Grapsus grapsus is one of the most common crabs along the western coast of the Americas. It is known variously as, ""red rock crab"", ""abuete negro"", and along with crabs such as Percnon gibbesi as, ""Sally Lightfoot""."
"We studied many of these on the roots of red mangroves at high tide on this particular afternoon. The carapace on this individual was about 1 to 1-1/4"" wide. They are quite camera shy so I was fortunate to get this image. They almost invariably move/rest on the roots with their head pointing downward towards the water; this image was rotated for a better presentation. I hasten to add that I got this ID from an invaluable reference: Charles Sobczak (2010), Living Sanibel, A Nature Guide to Sanibel & Captiva Islands. This is a superb introduction to a wide array of flora and fauna of the area."