The Slender-legged Fiddler Crab, Uca tenuipedis (Fiddler Crab of the Week)

The Slender-legged Fiddler Crab (Uca tenuipedis), is a very small species from the eastern Pacific Ocean, ranging from about El Salvador to northern Peru. It is similar in size to some of its sympatric associates, such as Uca batuenta, Uca intermedia, and Uca saltitanta, but is readily distinguishable from the first of these by the somewhat triangular shape of the pollex and manus, and the latter two by its color: a fairly cryptic-colored brown and gray body, with a white pollex and pinkish-salmon dactyl and top part of the major claw.

Photos by M. Rosenberg, Panama, 1997.

The waving display of this species involves bringing both the large and small claws straight out to the side, pausing for a moment, then bringing them up and forward in a circle back to the starting open-wide position. The whole body rocks backwards slightly with this motion and sometimes the first few legs may come off the ground as well.

Unlike some of the other local species, this one seems to stay closer to the shoreline, found among the muddy stream banks or the fringes of mangroves rather than out on the open mudflat.