This Beetle Uses Its Poop as a Shield or Sword

A tortoise beetle and her poo-tipped brood doing the most disgusting impression of a Bloomin' Onion ever.

In one of greatest sketches from the show Upright Citizens Brigade, an enterprising redneck sells a poo stick—that’d be poo on the end of a stick—for $125. It’s the “latest in A1 protection,” and even comes with a few free replacement cartridges—that’d be extra turds. It’s so effective the redneck doesn’t even bother selling mace or tasers, and so dangerous one once killed his son.

Aside from being a bit overpriced, it’s hard to deny the effectiveness of a poo stick in warding off attackers. Which is exactly what the larvae of the tortoise beetles have been doing for millennia. Not content to just sit there and get eaten, using a highly elongated and mobile anus, they build a tower of poo on a special structure on their backs. It’s dextrous too: When threatened, the larvae can smack their foes with the so-called “fecal shield.”

Insects can opt to dump a whole lot of eggs into the ecosystem and just hope they make it on their own, but tortoise beetles are doting mothers, forming a system known as subsociality. A beetle mom begins by laying a cluster of eggs, typically on the underside of a leaf, at a very specific time of year: the rainy season. This ensures the young will have plenty of food when they hatch. When they do, she guards them fiercely, guiding them around as a herd to prime feeding locations.

Enjoy this image of an adult tortoise beetle, because it’s going to be all poo and anuses from here on out.

During all this time—from the moment she lays the eggs until the larvae have transformed into adults—she’s so preoccupied she doesn’t feed a bit. For as long as two months. “So they feed together, and she’s with them all the time making sure that none of the larvae walk away or get lost,” says Caroline Chaboo, a biologist at the University of Kansas. “She’s really a helicopter mom, constantly around them making sure that they stay together.” Of particular concern are predatory wasps that swoop in and nab the young. Mom is one hell of a scrapper, though, and if she’s knocked off a tree in a tussle she’ll inevitably make her way back to the larvae (unlike regular tortoises, tortoise beetles can indeed fly).

So, the shit shields. They’re all built on top of a structure called the anal fork that the larva can manipulate to reach any part of its body. Poke one on its left side, and it’ll give you a targeted smack right there. Or sometimes, the shield can be so big that the beetle is restricted to just flipping it up and down. Much of the structure is in fact old exoskeletons, which the beetle sheds and forces to the back of its body—exoskeletons that Chaboo suspects could sequester toxins, making the shield that much more effective.

That translucent tube is the larva’s highly mobile anus, which is a sentence I just wrote.

Waste Is a Terrible Thing to Waste

So how can the larva so deftly crap all over itself? “This part is quite hilarious because their anus—I’m talking to a man in California about the anus of a beetle larva—so the anus is this long tube that is extremely flexible and maneuverable,” Chaboo says. “So it can extend and deposit the feces exactly where they want to place it.”

What you end up with is a noxious weapon that the beetle can use either like a shield or a sword. And as a united brood, their effect is pretty damn intimidating. When threatened, even by something as simple as a scientist’s shadow passing over them, the larvae form up into a circle, pointing their butts and shields outward, as their mother charges around the perimeter. It’s just like buffalo circling around their babies with their business end facing out, only the beetles are wielding doo-doo instead of horns. How the young are communicating with their mother isn’t quite clear yet, though Chaboo suspects little squeaky noises they emit may have something to do with it.

En garde!

“This is just basic neurobiology,” says Chaboo. “It’s crazy. The investment is what stuns me, is that the female is there guarding this brood for two to three weeks and putting her life on the line. And the assault on the brood is never-ending, it’s just a constantly vigilant mother who can protect her brood to adulthood.”

An Ugly Duckling Becomes a Swan. Only With, Like, More Legs and Stuff

When the young make it to adulthood and finally part ways, they’ll ditch the shit shield in favor of more civilized garb. As an adult, the edges of their exoskeletons are actually clear, and their shape allows them to hunker down on a leaf or some such without exposing their legs to nippy predators. And they come in all manner of colors and iridescence, with males and females sometimes sporting entirely different shades.

Yet not all tortoise beetle males are like the others. Some fellas are shaped more like females, and Chaboo reckons these guys are sneakers. So instead of competing with larger rivals, as the big sluggers battle the sneakers slip past them and mate with the ladies undetected. (This brilliant little evolutionary trick actually happens elsewhere in the animal kingdom. Some smaller male cuttlefish, for instance, will change their color and posturing to mimic females, then sneak right under big males guarding a harem and have a romp.)

Some species of tortoise beetle can also change their color on the fly, though this probably doesn’t have to do with mating, since both sexes can pull it off (if it were just the males doing it to impress females, it’d be a different story). Their elytra, the wing covers that make a beetle a beetle, have a very special structure. “Think of a parking garage, with a roof and a floor and pillars that support the internal structure,” says Chaboo. “Fluid flows within that empty space. We suspect that by controlling the flow of fluid in that space these beetles can change their color.”

More research from Chaboo is forthcoming on the exact mechanisms involved, but these beetles go from a brilliant, shiny gold to a dull brown in milliseconds. That speed might suggest this is a matter of camouflage. While having all of those highfalutin colors may make you more attractive to mates, for instance, they also make you more attractive to predators (alternatively, vibrant hues may serve as a warning that the beetle is toxic). Being able to put on a new outfit on the fly may be good for protection—when you don’t have the option of slapping your enemies with your turds anymore.

Read more at Wired Science