The group name Benthozoa comes from the hypothesized transition of its early ancestors from an entirely
holopelagic life cycle to one with a
benthic adult form. Schultz
et al. proposed the alternative name Myriazoa (meaning "numerous animals") as a replacement that avoids assumptions about evolutionary novelties. They do not recognize morphological characters uniting Porifera to the
Parahoxozoa, but found that patterns of gene distributions across chromosomes strongly support the occurrence of an irreversible group of changes in the shared ancestor of Porifera and Parahoxozoa but not in the ancestor they share with Ctenophora. Ctenophores share multiple features with Parahoxozoa, including
extracellular digestion,
germ layers and a
nervous system. The absence of these features in sponges implies either convergence between the two other groups, or their loss in Porifera. The following cladogram is adapted from figure 4g of Schultz
et al. (2023), although Nielsen (2019) notes that whether Cnidaria is considered sister to Placozoa or Bilateria varies among recent phylogenetic analyses. }} ==References==