This beetle can skim across the surface of water so fast that it has been said to be akin to water skiing.
Meet Galerucella nymphaeae, a type of Water Lily Beetle.
Haripriya Mukundarajan from Stanford University and her colleagues have been filming the Galerucella nymphaeae in the lab, this is to see how they manage to travel on the surface of the water at speeds of up to 0.5 metres per second. In scale that would be a human travelling at 500km/h.
to figure out how they stay on the surface while travelling at speeds of up to 0.5 metres per second –which scaled for size woul be equivalent to a human travelling at about 500km/h.
These beetles moce so fast that they end up interacting with ripples that is has generated by their own motion, leaving their journey fast but bumpy.
Her team also found that skimming across water expends more energy than flying in air. Water lily beetles are also agile in air, but only fly occasionally, for example when threatened by predators.
They could be moving on water rather than in the air because they feed on water lily leaves floating on ponds, say the researchers.
And their legs are covered with tiny hairs that repel water while a claw at the tip is hydrophilic, allowing them to pin themselves to the surface of the water. “This structure is critical for the beetle to maintain its level exactly on the water surface,” says Mukundarajan.
“I’m surprised that they have something this elegant,” says Jake Socha from Virgina Tech in Blacksburg, who has previously uncovered the aerodynamics of flying snakes. “It suggests that skimming is evolutionarily important.”
Understanding the motion of the beetles could help us develop robots that move across water quickly. Many current designs are based on water striders, which move more slowly.
Mukundarajan also thinks studying the beetle’s wings could give insight into a phenomenon that occurs when an aircraft is flying low. “The beetles flatten their wings when they are close to the water,” she says. “This could create tiny vortices that reflect off the surface to give them a boost.”
Journal reference: Journal of Experimental Biology, DOI: 10.1242/jeb.127829