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Beetle Heads for the Exit When Swallowed by Frog

Escape hatch message on a tugboat
M.Moira/Shutterstock

Thanks to evolution, many species have developed defense, camouflage, and escape mechanisms to avoid getting eaten by other species. But science has never recorded one animal actively escaping from another after becoming a snack—until now. 

Escaping Through The Vent

Writing in the journal Current Biology, Kobe University ecologist Sugiura Shinji found that the aquatic beetle Regimbartia attenuata basically runs through a frog’s digestive system after it’s been eaten to emerge through the frog’s vent – which is the nice, scientific way to say butt. Not only that, but the beetle can encourage the frog to defecate to ease its escape further.

In his study, Sugiura fed adult beetles to four different frog species. In 90% of the cases, the beetle was found exiting the frogs’ bodies in fine shape within six hours of being eaten, with the fastest escape artist clocking a time of only six minutes. These times are much quicker than the frog’s usual digestive process, which takes more than 24 hours. This led the researcher to conclude that the beetle actively works its way to the frog’s anal opening.

Plus, because that opening is usually sealed tight by the frog’s sphincter muscle, Sugiura concluded that the beetle likely stimulates the frog’s gut to get it to defecate – but how that is accomplished requires further research.

“Further experiments are needed to investigate how to stimulate the frogs to defecate,” Sugiura told Wired. “However, I speculate that R. attenuata use legs and the body to stimulate the frog’s hind gut.” 

Leg Waxing

To further test his theory, Sugiura locked some of the beetles’ legs in wax and then fed them to the frogs. In those cases, the beetles became just like any other frog food, taking more than 24 hours to emerge in a very much digested form. 

Apparently, the aquatic beetles have adaptations for living in a watery world that might help them inside their amphibian predators. According to Wired, they are not only quite accomplished swimmers, but they can breathe underwater by trapping an air bubble beneath their wing covers. Both skills could help the beetles survive and swim through the frog’s digestive tract, emerging as if it was just another day living in the wilds of Japan’s paddy fields.

You can watch the whole process play out in the video below—if you’re into that sort of thing.