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Animals have a lot of different strategies for
getting themselves out of tight spots.
But most of them involve evading capture…
Because there’s just not a whole lot you can do if you’ve already been eaten.
Unless you’re this particular type of water beetle.
Regimbartia attenuata is a water scavenger beetle
found all across the eastern half of the globe,
from Australia to Japan to the Arabian Peninsula.
It’s small.
Dome-shaped.
Kind of cute.
But it didn’t get a whole lot of attention until biologist Shinji Sugiura
fed one to a pond frog and then watched it crawl out the other end.
And it wasn’t a fluke, either.
He’s since discovered that 9 times out of 10,
this particular brand of beetle makes its way out of a pond frog’s digestive system
alive.
And at least two thirds of the time,
hese beetles escape the digestive tracts of four other frog species,
although the success rate seems to vary a bit depending on the frog.
Now, the first thing you’ve got to wonder is if these beetles are actively trying to
escape,
or if they’re just waiting around until they get pooped out.
Suguira wondered that, too.
So he devised an experiment.
He used wax to glue together the legs of some unfortunate beetles,
so they couldn’t move, then fed them to frogs.
Spoiler alert: the beetles died.
Also, it took a long time for them to reappear; like, more than 24 hours,
while unglued beetles generally made their escape in less than six.
One was even observed exiting after about six minutes …
maybe it wasn’t his first time?
Anyway, this seems to confirm that the beetles are actively escaping.
But while their survival seems kind of miraculous,
it’s probably evolutionary luck.
Regimbartia attenuata is an accomplished swimmer,
so once inside a frog it just keeps doing what it does best.
It also has its own personal scuba tank — it stores a bit of air under its exoskeleton,
so the oxygen-free environment isn’t a problem, either.
And water beetles are kind of naturally water-tight.
So that hard, armored shell probably gives it some protection
against the frog’s digestive juices.
But then, there’s that final, seemingly insurmountable barrier:
the frog sphincter.
The beetles aren’t strong enough to force the opening.
v.
You see, the beetles always come out head first.
So, researchers think that they’re mechanically stimulating the hindgut to induce the frog
to poop.
This talent for surviving digestion isn’t totally unique in the animal kingdom.
Some snails can make the trip through a bird’s gut,
and some fish eggs may occasionally survive, too.
But they’re not quite as good at it; According to experimental studies,
only about 15% of snails make it through alive, and less than 1% of fish eggs do.
Plus, they don’t play an active role in their eventual escape.
Interestingly, though, when scientists tried other beetles from the same family, they all
got digested.
Still, it’s likely Regimbartia attenuata isn’t the only water beetle
that survives digestion.
Most humans don’t spend their downtime looking at frog butts,
so we may be missing the evidence for this weirdly effective survival strategy in other
species.
Or, maybe, the other water beetles are just like, “Nope.
Digest me, already.
I draw the line at sphincters.”
Anyway, that’s all I’ve got on water scavenger beetles.
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