Genetic analysis of an obscure, worm-like creature retrieved from the depths of the North Atlantic has led to the discovery of a new phylum.From the U Florida press release:
Scientists have long been puzzled by the half-inch-long Xenoturbella first retrieved from the Baltic Sea more than 50 years ago. Early genetic research identified it as a type of mollusk but more precise genomic sequencing showed that Xenoturbella belongs to its own phylum.
It is one of only about 32 such phyla in the animal kingdom. "During the last 50 to 60 years, only a few new phyla have been established," Moroz said.
Perhaps more significant, the analysis of Xenoturbella seems to confirm that human beings and other chordates share a common ancestor. Its extreme characteristics suggest that this common ancestor – one the creature shares with its sister phyla, echinoderms and hemichordates, as well as chordates -- did not have a brain or central nervous system.
A reconstructed genetic record reported in the article also implies that the brain might have been independently evolved more than twice in different animal lineages, Moroz said. This conclusion sharply contrasts the widely accepted view that the centralized brain has a single origin.
