Upside-Down Beetle Walking Underwater

The insect world continually surprises scientists who sometimes see an insect do something that no one had noticed or paid attention to before. For example, most of us have witnessed water striders that use surface tension to skate along the top of quiet pools of water. However, recently a researcher in Australia noticed a beetle walking on the water surface, but upside down from below. The upside-down beetle is a species of water scavenger beetle (Hyrophilidae) and the first beetle in which a scientist has documented this behavior.

Some snails can slide along the underside of the water surface on a layer of mucus. However, these beetles seem to have a unique method of walking upside down in the water. They can even stop and pause or change directions as if walking on a solid surface. This gives the beetle some advantage to avoid predators.

This behavior was noticed and documented by behavioral biologist John Gould of the University of Newcastle in Australia. The picture is of another water scavenger beetle in Ohio. However, you can see a video taken by Gould on YouTube at THIS LINK.

Apparently, the beetle traps an air bubble against its upturned belly, allowing it to press against the water-air boundary. The beetle’s feet must have some way of getting traction to enable movement. Robotics experts have learned from the ability of water striders to walk on the water’s surface. Therefore, it seems likely they will find some uses for walking upside down under liquid surfaces.

Gould said that “the findings about the upside-down beetle highlight how often we ignore or miss the amazing things the smallest animals are doing every day, and describing the natural history of the small is just as important as describing the natural history of any large mammal or bird.” In addition, the upside-down beetle reminds us that we can learn by studying God’s creation and the design He built into every living thing.

— John N. Clayton © 2021

Reference: Science News, July 31, 2021, and Ethology.