The asymmetrical growth of otoliths in fish is affected by hypergravity

Size and asymmetry (size difference between the left and the right side) of inner ear otoliths of larval cichlid fish were determined after a long-ter m stay at moderate hypergravity conditions (3g; centrifuge), in the course of which the animals completed their ontogenetic development from hatch to freely swimming. Both the normal morphogenetic development as well as the t imely onset and gain of performance of the swimming behaviour was not impai red by the experimental conditions. However, both utricular and saccular otoliths (lapilli and sagittae, respec tively) were significantly smaller after hyper-g exposure as compared to pa rallely raised 1g control specimens. The asymmetry of sagittae was signific antly increased in the experimental animals, whereas the respective asymmet ry concerning lapilli was pronouncedly decreased in comparison to the 1g co ntrols, These findings suggest, that the growth and the development of bilateral as ymmetry of otoliths is guided by the environmental gravity vector. (C) 1999 Elsevier Science Ltd. All rights reserved.