Re: How many animals are there that can't be placed in any of the phylums?

The short answer is that there are no animals that can't be placed into any phylum, but this is just because new phyla are created when it?s necessary. In 1995 Funch and Kristensen discovered a strange organism growing on the "lips" of lobsters, and this later became the new phylum Cycliophora. Kristensen had previously discovered the new phylum Loricifera.

Sometimes a new phylum is created, as in the above examples, and sometimes other levels of taxonomy are created. The Burgess Shale has some truly bizarre fossils in it, but many of the weirdest didn?t seem to belong in any phylum. In the end many were placed in the Crustacea, though a new order, Dinocarida, was made for them.

So yes, animals are found that don?t fit into any known phylum, but in that case a new phylum is made for them. The current taxonomy doesn?t claim to encompass every organism on the planet, just those that we know about. When new animals are found, space is made for them, whether it?s as small as a new species or as major as a new phylum.

Sources

The description of Cycliophora: Funch, P and RM Kristensen. 1995. Cycliophora is a new phylum with affinities to Entoprocta and Ectoprocta. Nature 378:711-714.

Description of the Loricifera: Kristensen, RM. 1983. Z. zool. Syst. Evolutionsforsch. 21:163-180.

Information about the Burgess Shale: http://burgessshale.com/