There are around 100 species of terrestrial fiddler crabs in the genus Uca. They are characterized by the extreme claw asymmetry of the males. I had the chance last week to see two talks from John Christy, a Smithsonian Tropical Research Institute scientist studying sexual selection and mate choice in the fiddler crab. The Uca genus is diverse in claw morphology, male displays, and burrow construction. As an example of the diversity across the species one species mentioned which is extremely understudy was the so-called styled fiddler crab (Uca stylifera) which can be seen below. The asymmetry normally exhibited in the claw has been extended in this case to the legs as well and includes the weird eye stalk (which is jointed!).
Get your fiddler crab fix here by checking out the whole genus!








