Hundreds of millions of years of evolution have produced animals with remarkable defence systems that it’s hard to believe were the product of random mutations.
Exploding ants, projectile-vomiting seabirds, lizards that can spurt blood out of their eyes – they’re all here on Planet Earth. They make defending castles using barrels of hot tar look like kids’ stuff.
But bombardier beetles have taken their personal safety to a whole new level. Within their bodies, they contain the equipment to create a chemical reaction that would make the average science nerd proud. They were walking school laboratories before Homo sapiens was even a glint in our distant prosimian ancestor’s eye.
Threatened bombardier beetles – a group of insects in the Brachini subfamily with 649 known species – do something you’d think was impossible. They contain two separate canisters of liquids that, when threatened, they mix together to create literally (yes, 100˚C!) boiling chemicals that they spurt out of their backside into the faces of their attackers.
The reaction makes a “squeaky pop” sound, entomologist Wendy Moore told National Geographic. “It’s shocking, it really gets your attention,” she added.
An experiment carried out by researchers in 2018 has shown they can trigger this defence even if they have been caught unawares and swallowed. They fed bombardier beetles to two species of toads, and found that almost half of them – 43 per cent – vomited up the beetles up to two hours after swallowing them.
The mini explosions were even audible from within the toads’ bellies, and all of the beetles that came back up survived for at least another two weeks after their ordeal. And, you’ll be glad to hear, the toads were unharmed, too – a rare win-win for nature where winners and losers are usually the two sides of a very unforgiving coin.
British readers will be pleased (or possibly not) to discover there are bombardier beetles in the UK – two species, in fact, the common and streaked, though both are rare here. They have “blue-green wing cases with a narrow orange-red head and back”, according to the invertebrate conservation group Buglife, though the streaked bombardier also has “a distinctive red dash along its back”.
They favour the relatively warm and dry climate of the East Thames area because they are at the northern edge of their range, and they prefer brownfield sites with poor, thin soils. But they are also found on every continent apart from Antarctica, usually favouring temperate woodlands or grasslands.
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