EsophagusR. attenuata’s escape route through the body of P.nigromaculatus StomachSmallIntestineLargeIntestineCloacalApertureR.attenuata escaping from a blackspotted frog (P. nigromaculatus)*Cloacal aperture: This is the opening of the cloaca- a hole through which undigested food, urine, eggs and sperm are passed. It is mainly found in cartilaginous sh, reptiles, amphibians and birds. Some mammals also have a cloaca. 1324511RESEARCH AT KOBESo you continued lming the frog and then discovered that the beetle had escaped about an hour or so later, right?I did not lm the escape the rst time it happened. When I checked on the frog about an hour and a half after it had eaten the beetle, I noticed that the beetle was in the case too. I always check the frog’s mouths after they have eaten to see if the insect has been swallowed. I was certain that the frog had eaten this insect so I realized that it may have escaped from the frog. At that point, I didn’t know whether it had escaped by being regurgitated, like the bombardier beetle, or if it had escaped via the frog’s behind (i.e. through the cloacal aperture*). Subsequently, I was able to capture the beetle’s escape on video and could conrm that it came out of the frog’s behind.Is it rare for a creature to be able to escape via the predator’s behind?Yes, it is. Although there are some species that are known to do this, they are usually expelled at the same time as the excrement.Normally, consumed insects are expelled from the frog’s body as excrement 1 to 2 days after being eaten. R. attenuata is able to escape alive after a period of time ranging from a few minutes to six hours at the longest, without having to wait for the frog to excrete it. I think that it does this either by actively trying to escape or by stimulating the frog’s gut to promote excretion. I believe that this is the rst time that such a quick, active escape of prey from the body of a predator has been documented.Do you have any plans to research how the beetle promotes its excretion?I have conducted experiments where the frog was given an R. attenuata that cannot move its legs. The beetles were unable to escape from the predator’s body in these cases. I am not yet sure exactly how R.attenuata escapes but I believe that it uses its legs and movement to promote excretion rather than producing a chemical substance. For example, people use suppositories as a laxative. Suppositories work by causing gas to build up when they are inserted into the rectum, which in turn puts pressure on the digestive tract and promotes excretion. I think the movements of R.attenuata might have a similar eect, as in they put pressure on the frog’s digestive tract which promotes excretion. However, I recorded video footage of an R.attenuata crawling out of the cloacal aperture, so it is not completely impossible that the beetle is able to escape using its own strength. Also, R. attenuata has a tough, streamlined body, which may provide protection against the frog’s digestive juices and aid its escape from the cloacal aperture.
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