Laterality affects coloration in Red Sea Ghost Crabs (Ocypode saratan)

Abstract The ability to change colors or appearance to blend into the background habitat is essential to ensure an individual's survival. This is especially challenging in a heterogeneous habitat such as the intertidal zone of a seashore, which is the primary habitat of crabs. The Red Sea Ghost Crab (RSGC) is endemic to the Red Sea, and in Israel, it is found only at one beach. We discovered that right-clawed crabs are lighter colored (i.e., yellow, sand) than left-clawed crabs (brown, purple), consistent with their daily activity. The closest to the water were the sand-colored, left-clawed crabs, while the farthest up the beach were the yellow-colored, right-clawed crabs. Moreover, we observed purple-colored, left-clawed crabs during low UV radiation, while during high UV radiation, we observed brown-colored, right-claws crabs. In explaining the observed segregation, we speculate that claw lateralization and body colors are common in the social signaling system. Symmetrically identical individuals can signal their condition to their competitors by colors. However, this part of the signaling is under the pressure of the intensity of sunlight.