Color Dependence of Motion Vision of Uca pugilator

Abstract

By Krista Murphy, Neurobiology

Advisor: John Layne

Presentation ID: AM_ATRIUM20

Abstract: The majority of marine invertebrates have two genes that code for visual pigments. The fiddler crab, Uca pugilator, is unusual in that it has three genes that code for visual pigments, making it a potentially fascinating model or the study of color vision and it evolution. Previous research on the spectral sensitivity of this crab has shown that it is behaviorally sensitive to UV light, as well as wavelengths around 490nm(blue-green light), when exposed to an approaching abject - a looming stimulus. But there is another type of stimulus that may involve different visual pathways than those mediating responses to the looming stimulus, namely, the coherent motion pattern provided by a moving vertical grating - the optpkinetic stimulus. In this study, we investigated whether the visual pathway activated by the optokinetic stimulus is sensitive to similar wavelengths of light. To test this, crabs were subjected on all sides to a visual pattern of moving vertical bars. Different wavelengths were shown through the bars, ranging from 380-595nm and the contrast between the bars was varied between 10-90%. The crab's eye movement was tracked, and the amplitude of the movement was taken to indicate sensitivity to that wavelength. The results show that the fiddler crab's optokinetic visual pathway is not sensitive to UV light, but is sensitive to blue-green light. This indicates that the visual system uses separate pathways to process these two types of visual input.