Nephrozoa (nephridium; brain with neuropil, planctonic larvae)

Nephrozoa is the name of the group Bilateria excluding Acoela and Nemertodermatida. The term was proposed by Ulf Jondelius et al. based on the presence of a true brain and the presence of protonephridia as morphological synapomorphies. Concerning the Xenoturbellida it is unclear exactly where it is supposed to be placed within the Metazoa.

From here on I have chosen to have one tree for Deuterostomia and one tree for Protostomia. The high resolution in the Deuterostomia branch on this site might fool one into thinking that vertebrates are relatively plentiful. It is here important to stress that protostomians rule the earth. There is e.g. an extreme biodiversity amongst the insects on land. This in itself is perhaps not so surprising as insects invaded land a very long time ago, far earlier than the first amphibians. If insects can be said to rule above water the diagram below by Bouchet shows us that the seas are ruled by crustaceans, molluscs and worms. Representatives for Deuterostomia in the diagram are vertebrates, tunicates and echinoderms. So remember that protostomians have a higher biodiversity and their individual numbers are far greater than deuterostomians.