Morpho-anatomy of the otic region in carapid fishes: eco-morphological study of their otoliths

Carapid species are characterized by so-called otophysical structures (sonic muscles, broad first apophyses covering the anterior part of the swimbladder, etc.) The family includes pelagic ( Pyramodon and Snyderidia ) and benthic ( Echiodon ) species and ones that are either commensal with ( Onuxodon, Carapus ) or parasites of ( Encheliophis ) invertebrates (sea cucumbers, etc). The aim of the present work was to seek possible relationships between the structures of the inner ear (particularly the sagitta) on the one hand and otophysical structures and lifestyles within the Carapidae family. In the eight species studied, the otic cavity is wide, the saccular otosac and its sagitta are particularly developed. The sacculi touch each other on the median line. A comparison of the inner ear structures reveals notably that the species with the most developed sagitta and sacculus are those with the largest parapophyses and have a commensal or parasitic lifestyle.