Spectral Sensitivity Underlying Visual Escape Response Behavior in Uca Pugilator, Fiddler Crabs

Abstract

By Jacob Yazell, Biological Sciences

Advisor: John Layne

Presentation ID: 317

Abstract: To detect color, an organism must have the ability to discriminate between different wavelengths of light. Animals can gain information through the visual system such as species recognization, sex, defensive ability, health, size, social status and much more. Uca pugilator, fiddler crabs, are an exceptional species to study what importance color vision has in organisms. Many of their individual tasks and social interactions rely on the visual system. This study evaluated the possible contribution of color detection to intraspecific signaling by measuring spectral sensitivities of this species. To do this, we developed a behavioral test apparatus that is novel for animal color sensitivity measurement. This was done by modifying an LCD screen to transmit a range of specific wavelengths. A dark, expanding disk is presented against a colored background as a looming stimulus to frighten the crab and induce a response. We have found that U. pugilator is sensitive to wavelengths between 360-535 nm previously in this study. There were two peaks of sensitivity near 361 nm and 500 nm, which is predicted by the amino acid sequence similarity of the crab's opsin found in previous studies. My role has been to test if the fiddler crabs can discriminate between 380 nm (Ultraviolet) and 525 nm (green).