Tuesday, July 25, 2006
Velvet worms, living fossils that look like a child's rendition of caterpillars, are more closely related to spiders and scorpions than to butterflies, according to new research.
Known to scientists as onychophorans, velvet worms have been thought to be similar to the ancestors of modern arthropods, the jointed-legged creatures that includes insects.
Fossils that look very much like today's onychophorans can be found in rocks 540 million years old.
'When I looked at their brains, I was shocked because I didn't expect to see what I saw,' said Nicholas J. Strausfeld of The University of Arizona in Tucson. 'I just felt from their organization that these looked like spider brains, that they had more in common with spider brains than with other arthropod brains.'
Strausfeld, a UA Regents' Professor of neurobiology and the director of UA's Center for Insect Science, is a pioneer in using the architectures of cell arrangements within brains to tease out evolutionary relationships among arthropods, the animal phylum that includes all kinds of creepy crawlies, including insects, crustaceans such as lobsters and crabs, and spiders and scorpions.