Schooling behavior of tadpoles: a potential indicator of ototoxicity

Fish and tadpoles in schools use hair cells of their lateral line system to assess their position in relation to neighbors. This suggests that pharmaceutical agents that damage hair cells in the mammalian inner ear may also alter geometry in fish and tadpole schools. We used a computer-based image analysis system to examine the effect of the ototoxic aminoglycoside antibiotic, streptomycin, on school geometry for tadpoles of the African clawed frog Xenopus laevis. Tadpoles exposed to streptomycin in the surrounding water show a general tendency toward clumping, and an increase in the distance over which they orient parallel to neighbors, compared to controls. These behavioral responses appear in 18 min or less, and are evident in some tadpoles exposed to concentrations as low as 5 micrograms/ml. Results suggest that analysis of spatial relations in tadpole schools could serve as a method for rapidly detecting ototoxic potential of agents suspected of damaging hair cells.