Friday, 30 December 2011

Bristle Millipede

Image: Biopix, G Drange
In one way, the smallest porcupine in the world is the Rothschild's Porcupine from South America. In another way, it's not a porcupine at all. It's a millipede.

Bristle Millipedes are utterly puny members of the order Polyxenida. They reach less than 5 mm (0.2 in) in length and are found in soil, logs and trees. All the usual damp, dark areas with rotten vegetation to eat that just about any millipede would feel proud of.

One problem for the Bristle Millipede is that they lack the chemical defences that so many of their relatives use to secure life and at least a couple dozen limbs. This simply WILL NOT DO! And so our mild-mannered tyke must find another way to protect themselves from the slavering mandibles of their tiny world.

Their answer is bristles. Lots of tough hairs all over their body. Even better, many species gather a whole bunch of them together to form a kind of butt-brush. Never has a rear end been quite so dissuasive!

Image: Biopix, G Drange
It works in much the same way as a porcupine's spines. If an ant gets too inquisitive the Bristle Millipede turns his back on her and, just to get across the full extent of his antipathy, attacks her with his rufty tufty bum fluff.

It's a lot like a porcupine with those quills but with one significant difference: ants are insects with a powerful exoskeleton, so the Bristle Millipede can't pierce flesh like the porcupine can. They need another way to deal damage.

Luckily there's something else that insects have all over their body. Something that will prove their undoing. Can you guess what it is? Bristles! But they ain't got bristles like the Bristle Millipede got bristles. And when bristle meets bristle, there can be only one...

You see, the millipede has bristles with hooks on the end and barbs along the length, so they latch on to the ant's facial hairs and stay there. They also detach from the millipede with relative ease, so he can just walk off and leave the predator to her fate.

Image: Biopix, G Drange
Side view with legs and antennae
It's a bit like a lady receiving a stubbly kiss from her fella' and getting half a beard stuck to her face. One might imagine the poor woman's face crumple in disgust as she rushes off to clean herself up. The ant does a similar thing, her curiosity horribly sated and any attack immediately ceased.

What happens next depends on just how many bristles she's picked up. A few on her legs or antennae can be cleaned off pretty well in a few minutes. A more severe collection is an entirely different prospect.

Attempts to clean her hairy head and hairy antennae using her hairy legs and hairy mouthparts simply spreads the contamination all over the place. The hooks and barbs do their work, and it ends up like trying to clean glue off your hand using your other hand. And your mouth, for some desperate reason.

In the end, it's quite possible for the ant to become totally entangled, immobilised and, after several hours, dead.

Such is the strange brutality of nature's tiny worlds, red in tooth and bristle. Whatever comes to hand, I guess.


Check out this pdf for more details and some amazing close-ups of the bristles and their effects.


Bk Jeong said...

There is a weird ant that eats nothing but these guys, using specialized mandibles to scrape away the bristles.

Joseph Jameson-Gould said...

Ah, yes. I think I heard of them somewhere. I'll have to fish them out some time

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