Thursday, November 09, 2006
Xenoturbella is a 12-mm wormlike creature that would not seem very important, and no one thought much about it when it was first dredged from the Baltic Sea some 50 years ago. A new study, though, shows it is a very interesting beastie indeed. The critter is so different from everything else it belongs in its own phylum. There are only 30-some phyla in the animal kingdom (the exact number is disputed). Xenoturbella is literally brainless, and shows features indicating it has retained characteristics of the original missing link - the presumed common ancestor of all chordates, including humans. One researcher explained, "It is a basal organism, which by chance preserved the basal characteristics present in our common ancestor. This shows that our common ancestor doesn't have a brain but rather a diffuse neural system in the animal's surface."