Saturday, November 7, 2009

A Primer on Centipedes and Millipedes

A while back, I talked about how there were no vertebrates on land for the first 400 million years of this planet's existence.

What was the first land animal?

Stay with me...

That's right, centipedes and millipedes! The family collectively known as "Myriapods." One fossil manylegged myriapod goes back 428 million years, which makes them the first creatures on land. I don't think myriapedes get enough credit for that sort of innovation.

I find these bugs incredibly fascinating. There's one species of South American millipede that produces an oil on its exoskeleton that keeps insects away. Capuchin monkeys love to grab these millipedes and rub them all over their faces as perfect tropical bug repellent. There's even one type with the ability to glow in the dark!

The body plan of millipedes and centipedes are truly alien and strange. For instance, each individual segment of their bodies not only has legs that it uses to move in a "wave" fashion, but also an identical set of internal organs. Each has spiracles, little holes through which each segment nearly breathes independently.

What's the difference between a centipede and a millipede, you may ask?

Centipedes are poisonous and carnivorous. Come to think of it, the largest species of South American giants are even able to catch bats! It's worth pointing out the only place in the history of the world where a human has ever died from a centipede bite was in a Fu Manchu novel.

Millipedes on the other hand, are a little more gentle and feed on decaying vegetation at the bottom of forest floors. Some species can even roll into a ball to protect themselves! Not to mention one kind that can actually shoot hydrogen cyanide gas...

One sure way to tell by sight if something is a centipede or a millipede: centipedes have two leg sets in each body segment. It's incredible how many legs one of these bugs can have, with the upper limit at 300. In fact, millipedes in general are defensive fighters, able to produce a terrible stink to get predators away.

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