This worm is so different from everyone else we know that it merits its own phylum. Just to be clear, molluscs are a phylum, chordates (which includes vertebrates as a sub-phylum) are a phylum, sponges are a phylum… it’s a major division based on body plan. This body plan is Blob. Click here for a list of the other phyla. If I remember correctly, science hasn’t discovered a new phylum for at least 10 or 15 years, since a new one was found living on the lips of a larger fish.
P. Z. Myers at Pharyngula says:
A rather thorough molecular study of the organism has accumulated sufficient sequence information to place it in a phylogenetic tree, and it falls into the deuterostome clade, along with us chordates, echinoderms, and hemichordates. At the same time, it’s different enough that the investigators believe it warrants its very own phylum, the Xenoturbellida, bringing the number of extant deuterostome phyla up to four.
For more, read his article about Xenoturbellida
