Insects are notorious for their minuscule size. A flaw for some, their smalls size allows insects to have a unique relationship with the water-air interface compared to larger animals. Researchers recently discovered a unique aquatic beetle that defies the norms and strides across the surface of water upside down.
Unidentified Water Beetle
In a report published in the journal Ethology, entitled "Locomotion with a twist: Aquatic beetle walks upside down on the underside of the water's surface," researchers discovered a previously unidentified water-dwelling beetle that can scurry upside-down along the underside of the water's surface, seemingly as if the water was a solid plane. It is the first-of-its-kind documentation of a beetle species displaying the unique locomotion, known only in a small group of animals.
John Gould, lead author and behavioral biologist from the University of Newcastle, Australia, was initially on a mission to investigate tadpoles in ephemeral pools. When luck had it, he stumbled upon a small black speck in one of the pools, no bigger than a nail.
He explains that at first, the biologists assumed that a bug had fallen into the water and was struggling to swim across the water surface. He later realized that the unique insect was upside-down below the water's surface ScienceNews reports.
Gould immediately filmed the bizarre locomotion of the beetle walking under the water's surface as if it was a flat solid surface, resting from time to time and changing direction.
Studying the Upside-Down Scurring Beetle
Researchers found that there are a few snails known to slide along the underside of the water surface on a thick layer of mucus. However, little is documented regarding beetles walking in the same manner, only a few decade-old papers mentioning the phenomenon in passing.
What baffled researchers was how the unique beetle managed such a physically rare feat. Gould's recording showed air bubbles trapped along with the beetle's upturned belly. Researchers theorize that the bubble's buoyancy may have flipped, pinning the insect to the water surface's underside. This phenomenon then allows the unique beetle to place pressure on the water-air boundary with each step it takes, creating, as what Gould observed, tiny hills of water sprouting from the rare beetle's feet.
Tom Wiehmann, a movement physiologist from the University of Cologne, Germany, not involved with the study, says that seeing which parts of the insect were water-repellant and which weren't and information on feet anatomy could have propelled the research further.
Gould and his colleague Jose Valdez, wildlife ecologists at the Center for Integrative Biodiversity Research, Leipzig, hypothesize that the beetle uses its water-walking skills to stay away from predators ambush lurks at the bottom of the pools.
Researchers hope that future studies would reveal whether the unique beetles could switch to opposite sides of the water-air interface and leave the pools entirely. They suspect that future in-depth analysis on the physics of the aquatic beetle's upside-down locomotion could inspire advancements in technology and robotics similar to the accomplishments with water striders in Scientific American reports.
Check out more news and information on Animals in Science Times.
