Meeting Abstract
Underwater prey capture is a challenge for aquatic animals because of the high density and viscosity of water that impairs the movement of the predator and that can trigger the prey startle response. To circumvent these constraints, aquatic predators can adapt their morphology to be more streamlined. Snakes are an excellent model to assess whether these physical constraints have driven the evolution of their phenotypes as they have invaded both freshwater and marine environments. To circumvent the hydrodynamic constraints of prey capture underwater, previous studies suggested that the “ideal” head shape for an aquatic snake would be long and thin. In a recent publication, we demonstrated morphological convergence of head shape of aquatic snakes, but with a different pattern: aquatic species have more bulky and short head than the non-aquatic foragers. These results, although quite surprising, can make sense from a fluid mechanics point of view. Indeed, the physical constraints are directly related to the surface area that is facing the flow during the movement in addition to its shape. The aim of this new study is to assess whether this bulky and short head is more efficient to capture prey underwater. To do so, we use 3D-printed models of snake heads to measure the forces imposed on the different shapes during an impulsive motion that mimics an underwater strike. In addition, a force sensor was placed at the end of the strike arena to detect the magnitude of the pressure wave generated by the different shapes. Our results show that the force imparted upon the aquatic shape is indeed lower than the one recorded for the non-aquatic shape, meaning that having a thin and long head might not be as efficient as previously thought.
