Winged snails “fly” through water

New Scientist : Most zooplankton use their appendages to paddle through the water by way of drag-based propulsion, similar to the way humans use oars to row a boat. Now a species of sea snail, Limacina helicina, has been seen to use its wing-like appendages to propel itself with lift. To watch the so-called sea butterflies in action, David Murphy of the Johns Hopkins University and colleagues set up high-speed cameras in a tank of water. The video shows the creatures bringing their wings together and then quickly pushing them apart in a flapping motion like that of a fruit fly. Although such lift-based swimming is common in larger aquatic animals such as sea turtles, the researchers say it was unexpected for animals on the scale of zooplankton. The finding illustrates an evolutionary convergence of locomotion techniques for insects and gastropods.