English:
Parazoa means “near to animals”.
ZoologyParazoa have symmetry in all directions. Their tissues are amorph. Their cells are unspecialized, and thus they have no organs.
Animal theoryParazoa are identical to the sponges. In the
Animal theory the protozoa, unicellular animals, are added to this phylum. They have in common with the sponges the lack of specialisation. They just exist.
TaxonomyThey are basal Metazoa, animals. Metazoa can be split in
Porifera and
Eumetazoa, the main of the animal kingdom. Euemetazoa asre also called Diploblasts, Epitheliozoa, or Histozoa.
Sponges were first to branch off the evolutionary tree from the common ancestor of all animals, making them the sister group of all other animals.
ClassesCalcareaHexactinellidaDemospongiaeHomoscleromorpha