Protozoa: Sarcomastigophora, Apicomplexa, Ciliophora
Theories on the origin of Metazoa and the condition of Bilateria and coelomata.
The taxa of invertebrates. Of each group, unless otherwise indicated, morpho-functional anatomy, nutrition, reproduction, life cycle, habitat and phylogenetic relationships are treated:
Placozoa. Porifera. Eumetazoa: Cnidaria, Ctenophora. Bilateria: Acoelomorpha.
Protostomes. Lophotrochozoa: Rotifera, Platyhelminthes; Nemertea; Mollusca, Annelida; Gastrotricha, Sipunculida (generalities); Lophophorata: Bryozoa, Brachiopoda (gen.).
Ecdysozoa: Nematoda, Arthropoda; tardigrade; Onycophora; Chetognata; Kinorhynchia, Loricifera (gen.). Deuterostomes: Echinodermata; Emichordates (gen.); Urochordata; Cephalochordata (gen.).