The Basal Phyla

The sponges (Porifera) have traditionally been regarded as the sister group to all other animals.

In the last decade much evidence has changed this view and placed the sea gooseberries (Ctenophora) in this position although there is also molecular evidence for maintaining the Porifera in this position.

The third phylum in the group includes the plate animals (Placozoa) this small phylum is seen as above the Porifera and Ctenophora but then in a sister group relationship to all other animal.