During a recent backpacking trip through California's Kaiser Wilderness, a group of campers found themselves having a curious "conversation" ... with a pondful of bugs. In a short clip of the waterside spectacle, one camper's repeated calls are met by countless rippling reactions – and it's mesmerising to watch. 

So what exactly is going on here? Several hunches are floating around about the identity of these tiny ripplers – from mosquito larvae to so-called "water aphids" – but our best guess is that the insects are water striders. (We've also reached out to experts for more information about this sweet-water surface dance, including a more assertive ID.)  

Also known as "water skippers" or "pond skaters", water striders belong to a group of insects (family Gerridae) known for its ability to exploit the stickiness of water molecules. Their long, spindly legs are covered in tiny hairs, which help the invertebrates sit comfortably atop their aquatic domain. Air trapped between the hairs keeps the striders from breaking the water's surface tension, and they're able to skip merrily along. 

Interestingly, this isn't the first time an echoey back-and-forth of this kind has intrigued viewers online:

Water striders and a variety of other water bugs use ripples to communicate with one another, so it's not surprising that the California swarm was sensitive to the vibrations produced by "Hey!" on repeat. Without knowing all the details, explaining the behaviour more precisely is tricky, but for the sake of fun, let's surmise...

It's possible that the reaction is an instinctual defensive tactic: perhaps by moving en masse, the insects are able to confuse would-be predators like birds. Even for each individual water strider, the encircling ripples may work to divert attention away from the insect's actual position – and that emergency response could be propagated to nearby neighbours. Scientists suggested a similar predator-distracting explanation when they stumbled across this crazy caterpillar, which also reacts when disturbed by sound:

It's also possible that vibrations on the water caused by shouting are mistaken for the stirrings of potential prey. Water striders eat small insects that fall on the water's surface, as well as lurking larvae. As such, they're extremely sensitive to changes in their watery habitat. Compared to other surface insects, like whirligig beetles, they tend to remain relatively still while they hunt. If the stars of the California spectacle were some other water bug, we'd expect to see them shift around to a greater extent in between the calls from the bank.


Top header image: Pixabay