TIL: Bombardier Beetles Have One Of The Most Amazing Defensive Mechanisms!

Today I came across one of the most interesting papers I have read in a while! 

The main topic of the paper is what happens to Pheropsophus jessoensis beetles after being swallowed by a toad. The first thing that caught my interest is that these beetles are commonly known as "bombardier beetles".

So, why are they called that way? Well, turns out these little critters from Asia  have one of the coolest defensive mechanisms. When attacked, they eject a toxic spray from the tip of their abdomen! A spray that isn't only toxic, but also very hot, often reaching temperatures of up to 100 C, thanks to an exothermic reaction that occurs between some of the toxic chemicals.

The spray is usually more than enough to deter any hungry predators and make them go away. Here's a really cool, slow-mo video showing a bombardier beetle releasing it's spray to some unfortunate ants:

Jump to 1:00 if you can't wait!

So, now back to paper. In an effort to better understand this anti-predator mechanism and the anti-anti-predator mechanisms predators have in turn developed, the researchers designed an experiment to investigate how and if bombardier beetles could fair against two frog species, Bufo japonicusand B. torrenticola, that both commonly feed on beetles.

And to make the odds even worse for the beetles, before each face off they forced the beetles to exhaust their chemical weapon by poking them! A true David Vs Goliath battle, but without the sling in the equation! Would the beetles stand a chance against the much bigger frogs? Or fall easy prey?

Not surprisingly, with the beetles deprived of their only weapon the first part of the battle looked something like this:

(credit)

Yep, all beetles were swallowed in a matter of seconds:

 "Toads caught P. jessoensis by projecting their sticky tongues, and all of them swallowed the beetles "

Was the battle lost? Had all beetles fallen in the name of science just like that? 

No! They were still alive and many managed to survive their new higly acidic home for  long enough to recharge and release their chemical warfare!

A release loud enough to be even heard with the human ear:

However, an explosion was audible inside each toad, which indicates that P. jessoensis ejected a chemical spray after being swallowed. 

And in many cases the meal proved to tough to keep down:

The swallowed P. jessoensis induced 34.8% and 57.1% of the B. japonicus (N = 23) and B. torrenticola(N = 14) to vomit 12–94 and 15–107 min after being swallowed, respectively 

Many of beetles walked away unscathed and lived to see another day. Out of the 16 survivors, 15 lived for 17 days or more. One lucky fella was still alive 562 days after being vomited! Here's a video from the experiment showing one of those lucky warriors:

Jump to 00:40 for the main thing

According to the paper, this is the first time beetles have been recorded to spray and escape the insides of a predator and I was left with the impression that the researchers plan to do similar experiments in the future. I can't wait :D

Here's a link again to the study if you want to read all the details and results.

See ya tomorrow!