73.2 Friday, Jan. 6 The use of chromatic and achromatic cues during mate choice in the male blue crab, Callinectes sapidus BALDWIN, J.L.*; JOHSNEN, S; Duke University; Duke University email@example.com
Male blue crabs, Callinectes sapidus, rely in part on color cues to select appropriate mates. In previous experiments, we found that male blue crabs prefer females with red claws to those with claws modified to be white or dark grey. Our results demonstrating the blue crab’s ability to discriminate red from an isoluminant grey suggest that blue crabs are capable of color vision. Here, we have extended our study to investigate how color vision may function in relation to natural female claw color variations. Female blue crab claws vary in color from pale orange to deep red and could function in tasks such as gender identification, sexual maturity, or individual quality. However, given the blue crab’s dichromatic color vision system and limited range of spectral sensitivity, it is unclear if males are capable of discriminating between long-wavelength shades, such as red and orange. The behavioral trials presented here were intended to probe the ability of the blue crab, to choose between similar long-wavelength shades during mate choice. Overall, males show an innate preference for red clawed females to those with variations of orange claws. However, in tests between red and orange shades similar in both brightness and hue, male blue crabs did not show preference, suggesting that males are either not able or not motivated to discriminate between these shades. Further, our results suggest that male blue crabs may use a mixture of chromatic and achromatic cues to discriminate between long wavelength colors. The results are discussed in relation to blue crab color vision and possible function of claw coloration.