Friday, 16 November 2012

The Leggy Blonde Is So Weird!

Image: Paul Marek et al.
Illacme plenipes
Do you remember Illacme plenipes, that tiny, 3 cm (1.2 in) long millipede that, with its 750 legs, was the leggiest animal in all the world? Well, turns out it's weird in more ways than 750!

Paul Marek (International Man of Millipede) from the University of Arizona led a study to discover more about the abundantly sure-footed myriapod and has returned with news.

The millipedes were found in just 3 localities, each of them moist, oak-wooded valleys and all just a few miles from each other. It turns out they live quite deep in the soil, some 10 to 15 cm (4 to 6 in) down, and they keep themselves right on or under the sandstone boulders there. It's an incredibly specific habitat! These supermodels and their demands... no wonder the world tour was cut short.

Image: Paul Marek et al.
Those hundreds and hundreds of legs may well be used to keep a firm grip on the slabs of stone as well as to power them through the soil. Of course, that number of limbs requires an impressive body length, but there may be another reason for it... It's to do with their diet.

Most millipedes have a good set of chompers for grinding through the soft, vegetable matter that makes up their dinner, but I. plenipes is different. Their mouthparts form a kind of beak such that it looks like they're used to pierce fungus or delicate plant roots and drink up the innards. It's possible that this diet is low in nutrients or water, so the extra body length could allow for a longer digestive tract to help get the most out of whatever they eat. At least part of their digestive system also spirals along like a corkscrew, perhaps for the same reason.


Another odd thing about I. plenipes is that they're covered in all sorts of spikes and spines. With such a tiny size they can't help but appear quite smooth, but a really close look reveals all sorts of architecture all over their body. Some of these bits and bobs produce a substance similar to silk and which seems to be sticky. This isn't unheard of in millipedes but it certainly isn't common. It's thought this stuff could be used to stick to their favourite stone or as a defence against predators. I think it's to look silky smooth in front of the cameras.

It seems that their closest living relative is all the way over in South Africa, indeed I. plenipes is the only representative of its family in the western hemisphere and most of their other relatives live in the southern hemisphere. It's likely they split off some 200 million years ago when the super-continent Pangaea broke apart.

I. plenipes is a real trooper! So far from her family, clinging to life in her precise habitat with her eccentric adaptations and glorious collection of legs... Living under a rock isn't so bad.

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