Ahnelt H, Metscher B, Schwarzhans W 2026.
Journal of Vertebrate Biology 75, 25114. https://doi.org/10.25225/jvb.25114
Published online 27 February 2026

Abstract

The inner ear of teleost fishes is crucial for hearing and balance. It contains three pairs of otoliths that stimulate the innervating nerve as they move, with the saccular otolith (sagitta) being the largest in most taxa. Shape and size influence the motion of the sagitta and hence sound detection and balance, and are influenced by the ecological niche occupied by the fishes. We were interested in whether the otoliths differ along a spatial gradient in sympatric gobiids. We investigated free-living gobies (Istigobius Whitley, 1932), free-living but temporary burrowing gobies (Amblygobius Bleeker, 1874, Valenciennea Bleeker, 1856) and gobies living in shrimp burrows (Cryptocentrus Valenciennes, 1837, Austrolethops Whitley, 1935). The free-living species had thin sagittae, whereas the gobies inhabiting shrimp burrows had thick sagittae. The thickest otolith was found in Austrolethops wardi Whitley, 1935, a species that permanently inhabits shrimp burrows. The morphology of the otolith of A. wardi is unique among gobiids but reflects its relationship to the Gunnelichthys-lineage. We also analysed otoliths of blind cave fishes and fishes with atrophied eyes, in comparison with those not affected by cave-life. Alterations of the otolith morphology occurred in most of the cave fishes, and the most common alteration was thickening of the otolith.