Changes in centrum shape along the vertebral column in four species of partially sympatric dolphins from Southern South America: A 3D morphometric approach

DANS, SILVANA; MORA, MC; GONZÁLEZ JOSÉ, ROLANDO; MARCHESI, MC; BOY, C

Halifax

Congreso; 22nd Biennial Society for Marine Mammalogy Conference on the Biology of Marine Mammals; 2017

Society for Marine Mammalogy

INTRODUCTIONThe vertebral column is the primary skeletal structure employed by dolphins to generate the dorsoventral flexures characteristic of swimming and it has been described as a variably flexible 1,2 1 beam . Vertebral morphology and flexural mechanisms vary regionally along the column . Centrum shape is one of the features that allow determination of stable and flexible areas in the 3,4,5 6 column affecting the angle off rotation and displacement of one vertebra to the other . Information regarding size and curvature of the centrum facets are essential when characterizing typeand range of possible movements among vertebrae. 6,7 Description and functional interpretation of this variability are facilitated by recognizing structural units along the column . Any analyses on the vertebral column function should be made 5,6 from a different approach than the traditional perspective to describe which portion of the column contributes to undulation and to the displacement of the fluke; and how swimming style 3,6 may vary among species . 8 There is an association between flexibility and swimming speed, feeding habits and their environments . Flexibility is associated with high maneuverability and coastal habits whilst stable 8,9 body designs contribute to minimize energy expenditure and increases efficiency for prolonged swimming in pelagic habitats . Pelagic fast swimming species have osteological features that 8,9 promote a more stable vertebral column .The Commerson´s dolphin (Cephalorhynchus commersonii), the Peale´s dolphin (Lagenorhynchus australis), the dusky dolphin (L. obscurus) and the hourglass dolphin (L. cruciger) areclosely related species with distributions restricted to the Southern Hemisphere, being some of them partially sympatric. They show plasticity in habitat use and prey preference.