"In most of the experiments, the beetles reappeared within six hours, slipping out of a frog's anus, or vent. Though muscles typically hold the vent tightly shut, those muscles loosen up when the frog poops; the beetles could be stimulating the frogs' defecation reflex in order to temporarily open this unusual emergency exit, according to the new study."
There are mammals like rabbits that eat their own feces to get a second pass at digestion. Evolution has created an unbelievable amount of diversity in the natural world - it's a mistake to judge it by our own immune systems.
It is the only reproductive strategy of several major diseases, most notably cholera. So yes, obviously it is common. You know how cholera is notorious for spreading through communities very quickly? Guess how that happens.
Intentional consumption of other people's feces is rare, but that's not relevant to anything. If you eat something, it doesn't matter at all whether you wanted to eat it.
Slowing metabolism for a few hours is not too big a deal, but the adaptations to survive stomach acids maybe is? Frogs eat all manners of arthropods whole, without macerating, so whatever's down there is pretty aggressive.
I wouldn't expect a "dank basement" to require SCUBA gear. I agree with GP that this word use struck me as odd and distracting. Not sure what I expected to read about a beetle navigating an intestinal tract, but still.
