Velvet Worm

OK, I promised I wouldn't just post reviews-- though this in a way is a review of biological handiwork in a way. Here is a little critter I ran into in a big fat Animal book my daughter Emma and I checked out. There are only 110 species of them in the world, and they are very strange creatures if you try to classify them. Though they look kind of like a millipede or a caterpillar, they are not arthopods at all. Arthopods (arachnids like spiders, crustaceans, insects and centipedes/millipedes) have segmented bodies and a chitenous exoskeleton. The velvet worms do not. From Wikipedia:

Onychophores are thought to be closely related to the arthropods. The structure of their brains is similar to spiders, raising the possibility that they are most closely related to arachnids, though molecular analysis contradicts this.

...

The similarity of these creatures to caterpillars is not purely coincidental; as with most creatures, the larval stage of moths and butterflies are thought to represent, however inconsistently, previous evolutionary stages. Arthropods are thought to have evolved from a multi-segmented animal not entirely unlike both onychophores and caterpillars. In fact, the characteristics of larval insects are part of the evidence cited to support models of insect ancestors, for example in justifying how many segments and legs such creatures were thought to have, many of which evolved into other parts on modern insects, like antennae and mouthparts.

Anyway, fascinating little creatures.