So you happen to find that you have suddenly turned into an toad. Not only that, but instead of being at your computer you seem to have been transported to the coastal plains of Israel. Normally you might find this to be a slightly unusual set of circumstances. But you are now a toad, and toads, as a general rule, are not known for their mental prowess. So instead of having a mental breakdown at the discovery of being transformed into an amphibian, you go about your new life as if it is all you have ever known.
Before long you come across a beetle larvae that looks rather
tasty. As you approach it in hopes of getting your munch on, it
starts waving its antennae and mandibles at you. Your instincts
to attempt to eat anything small and twitchy kick in and you are
drawn towards what is sure to be a succulent meal.
The closer you get the faster and more frantically the little
morsel waves about. At this point, you cannot resist and pounce
on the beetle larvae and just as your tongue darts out to grab your
first meal as a toad, the larvae quickly dodges your attack and sinks its mandibles into your soft flesh.
Somewhere in the back of your toad mind, you realize that this
shouldn't be. You are the predator. Insects are merely
crunchy snacks to the likes of you. Yet despite this, you can't
ignore the fact that what you thought was to be your meal is now feeding on you.
You feel your blood being drained as you flail about frantically
trying to dislodge your attacker. As you
begin to weaken, a glimmer of hope returns to your tiny brain as you
feel the larvae dislodging itself from you. Could you have
finally fought off the surprise attack?
As you attempt to crawl away, the larvae repositions itself on
your back and bites down with surgical precision. You feel its
sharp mandibles biting through the muscles of your back, leaving you
effectively paralyzed. Whatever hope you had is now gone as the
reality of your situation sinks in. You are about to be eaten alive.
Now that you can no longer fight, the larvae can eat at its
leisure until there is nothing left but a pile of bones that used to
be your new toad self.
Had you not been transformed into a toad, you might have realized
that the flailing of antennae and mandibles was a cunning ploy of the
beetles and their larvae of the genus Epomis. These
beetles, whose relatives are all preyed upon by amphibians, have
turned the tables upon their once predator. Using the instincts
of amphibians against them, Epomis beetles actively prey on
any and all amphibians that still believe themselves to be the
The larvae feed exclusively upon amphibians, while the adults feed
on a variety of prey items, including amphibians. When
observed, the beetle or its larvae win the match close to 100% of the
time. Even after being eaten, the beetle or larvae will thrash
about until the amphibian is forced to regurgitate it. The
beetle, seemingly unharmed, will start feeding on the
would be predator right away. Even after staying in the stomach
for two hours, the beetle will not be beaten and once regurgitated,
will attack its choice prey item.
Epomis is the only known natural instance of a prey item
using its one time placement as a predated upon species as a means to
evolve into the predator. Since the beetle wins essentially
every match it finds itself in, there is little hope for the
amphibians to evolve a proper counter, nor are the beetles numerous
enough to damage amphibian populations significantly. Thus
leaving the species of Epomis in what is sure to be a rather
comfortable position as one of the most unexpected of predators.
Wizen G, & Gasith A (2011). An unprecedented role reversal: ground beetle larvae (Coleoptera: Carabidae) lure amphibians and prey upon them. PloS one, 6 (9) PMID: 21957480
Read the original paper.