Once Murphy and his colleagues were able to watch the sea butterfly in a special tank, visualizing its "wing" beats through the water, they noticed something that amazed them.
They'd expected the animal to use its wings like paddles in a boat, as do most zooplankton, but something else altogether happened.
"I said to myself, ‘Its wing stroke is just like what an insect is doing'," Murphy said in a press release. The underwater denizen was beating its wings in a figure-eight pattern, just as flying insects do.
Weird Sea Mollusk Has Hundreds Of Eyes Made Of Armor
What's more, Murphy and his colleagues found, the little mollusk's wing movements created the same type of vortices at the wing tips that help fruit flies generate lift.
"No one has actually been able to measure the flow around an insect doing this while it is flying, so that was kind of the holy grail of this area of research," Murphy said. "It really surprised me that sea butterflies turned out to be honorary insects."
The complete findings about this underwater aviator have been published in the Journal of Experimental Biology.