Meeting Abstract

P1.105  Sunday, Jan. 4  Hunting strategies of the mexican tetra fish Astyanax mexicanus larva STREETS, Amy*; SOARES, Daphne; univeristy of maryland; univeristy of maryland daph@umd.edu

The emergence of new species-specific behaviors is only possible due to the evolutionary malleability of neural circuits. In the tetra fish Astyanax mexicanus, we find a particularly good window into the adaptation of behavior during speciation. Currently, Astyanax is undergoing allopatric speciation and is extant in two forms: an ancestral, sighted river dwelling form and a derived, blind cave dwelling form. Although adult cavefish lack functional eyes, small eye primordia form during embryogenesis, but later arrest in development, degenerate, and sink into the orbit. Because the degeneration of the retina in the cavefish takes a few weeks posthatch, we hypothesized that these animals have a functional visual system as larvae. We used a visually guided prey catching assay to examine the level of performance of cavefish versus riverfish from 1 week to 1 month of age. We expected that if cavefish use their visual system alone to catch prey, then their performance would initially be comparable to river dwelling fish but then decrease as their retinas degenerate. Alternatively, despite having eyes larvae could use different hunting strategies from the beginning, such paying more attention to lateral line information. We tested animals in light and dark environments and after disruption of lateral lines by exposure to an aminoglycoside antibiotic (gentomicin), which kills hair cells. It appears that cavefish already use different exploratory and prey catching behaviors from the larval stage.