SEMINAR: "The ups and downs of buoyancy control in sharks and rays; a view from ecology and evolution."

Mid-water environments represent the largest habitable space on our planet, yet early vertebrate life evolved near the seabed of shallow seas. In order for early fishes to efficiently swim off the seabed and exploit pelagic environments, mechanisms to reduce submerged weight had to evolve. In particular, these mechanisms would need to help fishes to reduce their dependency on the seabed for resting and reduce the costs of swimming. The means by which this has been achieved differ substantially between animal groups, with implications for ecology, biogeography and evolution. Elasmobranchs (sharks, skates and rays), because of their mode buoyancy control, provide an exciting model system to study how and why animals have evolved divergent strategies and more importantly what factors drive the observed diversity. This seminar will take an integrative and comparative look at how buoyancy has shaped the ecology and evolution of elasmobranchs, by bringing together data from animal-attached sensors, comparative morphology and theoretical hydrodynamics.