You may have heard of the Bombardier beetle since they have a rather interesting ability. Or as National Geographic (cited below) puts it, “the infamous ability to synthesize and release rapid bursts of stinky, burning-hot liquid from their rear ends.”
Tell me more about the bombardier beetle!
There are actually over 500 species of bombardier beetle (and about 40 in the US alone). These creatures live in many different types of ecosystems. The boiling hot chemicals they can shoot out of their rears as a defense mechanism can reach temperatures up to 212 degrees Fahrenheit. And the beetle can shoot the spray multiple times in quick succession. The spray can also produce a loud popping noise as it is released, adding an extra deterrent.
The details are even more fascinating.
In the bombardier beetle, special cells produce hydroquinones and hydrogen peroxide which then collect in a reservoir. In order to spray, the beetle has to open a valve controlled by a muscle in order to release the chemicals into a separate “reaction chamber.” This chamber is lined with cells that catalyze the chemical reaction that makes the compounds hazardous to the beetle’s predators.
The catalases and peroxidases lining the chamber also aid in the reaction that generates enough heat to bring the mixture to the boiling point (though some of it becomes vapor). The pressure created by the gases closes the valve and expels the chemicals at high speed. Amazing, right?!
Should I be afraid of this creature?
People don’t need to be afraid of the bombardier beetle. They’re too small to hurt humans (about the size of a fingernail), and they don’t go around indiscriminately spraying. They use that function only as a defense mechanism against predators.
Bombardier beetles usually keep to wooded areas and fields and don’t roam around places with lots of humans. They typically have dark abdomens and reddish legs, antennae, and heads, in case you want to keep an eye out.
How on Earth did this beetle feature evolve?
Funny you should ask. Some creationists like to use the bombardier beetle’s two-chamber system as an example of their theory of irreducible complexity. They insist that since the beetle’s defense mechanism wouldn’t operate without two complex parts, they could not have evolved via small modifications and are therefore a product of “intelligent design.”
Most of the creationist rhetoric masquerading as science gives an incomplete or sloppy description of the beetle’s inner workings.
In fact, a step-by-step evolution of the beetle is pretty straightforward (even if it does seem weird to us). The beetle likely developed its ability to secrete chemicals as a defense mechanism that was released via the epidermis to make it distasteful to predators. While the steps in between are all hypothetical since we didn’t see the creature evolve, the development of the beetle we know now is easily broken down into tiny evolutionary steps we’ve seen in other species.
You’ve got to wonder why a creationist would assume God created this beetle specifically to shoot chemicals out its rear end. — WTF fun facts