Here’s why some water striders have fans on their legs

The appendages help the insects navigate flowing water

fan from water strider leg

FAN GAME  This feathery fan, seen here magnified, snaps open and shut on the legs of insects called Rhagovelia water striders, helping them traverse flowing water.

A. Khila

For an animal already amazing enough to walk on water, what could growing feather fans on its legs possibly add?

These fans have preoccupied Abderrahman Khila of the University of Lyon in France, who keeps some 30 species of bugs called water striders walking the tanks in his lab without getting their long, elegant legs wet.