Interfacial pumping inspired by snails

The apple snail Pomacea canaliculata exhibits a unique feeding mechanism to collect food particles floating at the water-air interface: while under water, it positions part of its flexible foot parallel to the water surface and generates rhythmic undulations. These undulations trigger a flow near the free surface that brings the food particles towards the mouth. With a robotic system employing an actuation mechanism of the snail foot, we systematically unravel the fluid mechanics of this feeding mechanism. We observe that floating particles far away are sucked into the robotic snail. Through particle image velocimetry we quantify the velocity field around the actuating sheet for a range of capillary numbers. I will discuss how the size and speed of these undulations give rise to a pumping effect near the interface to drive the particle-laden fluid.