Meeting Abstract
Vision is the primary sensory channel for numerous species and represents a key selective advantage throughout evolution. Many species have evolved the ability to perceive colors, and for many of these, color perception has become crucial in intra-species communication by relaying information to conspecifics about species, sex, reproductive state, defensive abilities, size, health, and social status. The Atlantic sand fiddler crab, Uca pugilator, is an excellent system in which to study the evolution and the importance of color signaling because many of their social interactions and individual activities rely on their visual system including burrow surveillance, predator avoidance, and mate attraction. During courtship, males visually attract attention by performing their stereotypical claw-waving displays and potentially using their carapace, leg and claw coloration as additional signals. This study aimed at assessing the potential contribution of color sensitivity to intraspecific signaling by measuring the spectral sensitivity of this species using a looming stimulus (i.e. expanding disc), which elicits an escape response in the crabs. By manipulating the wavelength and intensity of the looming stimulus, the spectral sensitivities of the crabs were assessed. This study found that the crabs are sensitive to wavelengths ranging from 360nm to 640nm, and are most sensitive near 490nm. There is a drastic decline in sensitivity to wavelengths longer than 590nm. These results coincide with the peak sensitivities (~480nm) predicted from Uca pugilator’s opsin gene sequence.
