Figure 3. Aquatic Caniformia have disc-shaped cochleae. A in The shape of water: adaptations of cochlea morphology in seals and oưers

Figure 3. Aquatic Caniformia have disc-shaped cochleae. A, exemplary wireframes made based on landmark coordinates along the cochleae of six taxa belonging to different subgroups (Mustelinae, Canidae, Lutrinae, Ursidae, Otariidae, and Phocidae). The arrangement in the graph corresponds to the PC1 vs. PC2 position in Figure 2. Aquatic Caniformia (blue cochleae) with negative PC1 and positive PC2 values have a compressed disc-shaped cochlea with a small number of turns. An increase in the number of turns correlates with the increase of PC1 values, from negative PC1 values with a small number of turns to positive PC1 values with a high number of turns (green shaded area). Further, the shape of the cochlea changes with negative PC2 values, a pyramid cochlea shape is found for Ursus maritimus and Enhydra lutris (semi-aquatic). With positive PC1 and PC2 values, cochleae are tower shaped (terrestrial, Mustela nivalis and Vulpes vulpes as representatives for mustelids and canids). B, Boxplot of the body size corrected centroid size for three different phylogenetic groups: Lutrinae (light blue, N = 7 species), terrestrial Musteloidea/Canidae/Ursidae (green, N = 21 species), and Pinnipedia (dark blue, N = 10 species). C, correlation analysis between PC1 values and the number of cochlear turns shows a clear positive relationship between an increasing PC1 value and the number of turns. The colour code is the same as in Figure 1. * = P ≤ 0.05, ** = P ≤ 0.01, **** = P ≤ 0.0001).