For most insects, they die when frogs eat them. However, one species of water beetle, Regimbartia attenuata, is unwilling to give up life so easily. Instead of surrendering to the frog’s digestive juices, the beetle passes through the amphibian’s throat, slides along the stomach, slips through the intestines, and crawls out of the frog’s bum, alive, active, and well. This beetle is unstoppable!
Some snails have survived digestion-by-predator through birds and fish by sealing their shells and waiting it out. However, research published on August 3 in Current Biology is the first to document prey escaping through the rear end of a predator.
Shinji Sugiura, the study’s lead author and an ecologist at Kobe University in Japan, set out to discover what kind of survival behaviors R. attenuata hold. In the laboratory, Sugiura paired the beetle with a frog that the insect regularly encounters in natural conditions while swimming through Japanese rice paddy fields.
The frog quickly ate the beetle. While amphibians lack teeth, they kill prey with one chomp. The journey through the acidic, oxygen-poor digestive track usually finishes off the insect, except for this little stubborn beetle. As Sugiura observed the frog, he noticed the beetle crawling out from the frog’s bum and hurry away, seemingly unharmed as if nothing ever happened.
The video above shows the beetle (R. attenuata) emerging from the back end of the pond frog (Pelophylax nigromaculatus.) Roughly two hours before this video was filmed, the frog ate the beetle. This is the first documented example of prey actively escaping a predator via the digestive system. “I was very surprised. I was expecting that the frogs might just spit out the beetles or something,” he commented.
Sugiura paired over 30 more beetles and frogs to confirm the results. He found that more than 90% of R. attenuate survived being eaten, outdoing other animals known to survive digestion-by-predator, which survived less than 20% of the time. It took six hours, on average, for the beetles to squeeze their way through and escape out the rear. However, one fearless and determined beetle completed the journey in only six minutes.
Sugiura suspects that R. attenuata’s aquatic lifestyle prepped it to survive digestion, and its robust exoskeleton likely shields the beetle from deadly digestive juices. Additionally, the beetle most likely doesn’t suffocate while inside the frog because it can breathe underwater through air pockets under its wings.
