Morell, M., Degollada, E., van der Schaar, M., Delory, E., Alonso, J.M., André, M. Computerised Tomography 3D reconstruction of odontocete ears related with the species acoustic sensitivity Proceedings of the Sea Tech Week, Brest, France, Oct 2006 Résumé: Understanding the acoustic capacity of dolphins to detect fishing nets is a key conservation issue. Because all odontocetes produce species-specific frequency ranges, differences in echolocation signals should reflect anatomical differences in the auditory pathways. Here, we investigated the relationship between 3D reconstructions and measurements of the tympano-periotic complex (including cochlea lengths and volumes) and the species auditory sensitivity, when it is known. All the ear measured lengths were strongly linearly correlated together (r > 0.9) in all species, as well as with the T-P volume complex. The proportion between tympanic and periotic bullae lengths has been found to be allometric in all the studied species. This constant ratio could be an indication of an existent functionality between both structures, adding some information to the role of the middle ear during target acoustic detection. All the studied measurements (cochlear volume, T-P volume, T length, P length, T-P length and animal length) appeared to be good a good indicator that defines the morphological differences between odontocetes, but other parameters may have to be taken into account to explain the species related acoustic sensitivity. Projet: Noise pollution effects on cetaceans