basal animals Porifera Ctenophora Cnidaria Placozoa bilateral symmetry hox genes important in body plan development genes body plan
The most basal animals, the Porifera, Ctenophora, Cnidaria, and Placozoa, have body plans that lack bilateral symmetry. Their relationships are still disputed; the sister group to all other animals could be the Porifera or the Ctenophora, both of which lack hox genes, important in body plan development.
