Meeting Abstract
Certain species of sacoglossan (Opisthobranchia: Mollusca) sea slugs are able to photosynthesize by way of kleptoplasty, where chloroplasts stolen from prey algae are sequestered inside of the slugs’ own cells. The duration of photosynthesis is quite variable among species as are their methods of maintaining sequestered chloroplasts by incorporating a variety of physiological, behavioral, and biochemical mechanisms. Elysia clarki is a sacoglossan sea slug capable of maintaining functional chloroplasts for 3-4 months of starvation. Previous studies have shown that the slug is capable of synthesizing chlorophyll a, which likely aids in prolonging photosynthesis and maintain chloroplasts. However, the slug may also employ additional methods to reduce the degradation of chloroplasts. To determine if behavioral methods, such as limiting light exposure, may be involved in prolonging photosynthesis, the phototaxic response of E. clarki was tested at 4 week intervals using time lapse photography over an 8 week period of starvation. The slug displays highly positive phototaxis, spending the vast majority of its time exposed to light and avoiding shade. As the duration of starvation increases the slug does not decrease the amount of time it spends in the light. This suggests that the slug seeks to maximize light exposure regardless of nutritional state in order to fully capitalize on its ability to photosynthesize.
