Vertebrata

In 5 kingdom system, Domain Eukaryote is classfied into: Monera, Fungi, Plantae, Protista, Animalia.
In 8 kingdom system, Monera is divided into Archaeobacteria and Bacteria, Protista and Plantae are further divided into: Archezoa, Chromista, Protista, Plantae.

Sponges are mass of cells without organization nor tissues and called parazoa. Organelles with tissues are called eumetazoa. Radially symmetrical organelles such as Cnidaria(sea anemones and jelly fishes) is called radiata. Note comb jellies Ctenophora are bilateral.

Platyhelminhes(planarians, flukes, and tapeworms) and Nemertinea(proboscis worms) are bilateria, and acoelom. Platyhelminthes has head and simple gastrovascular cavity. Nemertinea has complete digestive tract with simple vascular system, and hemoglobin. Rotifera(wheel animals) and Nematoda are pseudocoelom(Figure which have a complete digestive tract and vascular system. Bilateral bilateria which has coelom is called coelomates.

Among the coelomates, those developes determinate cells(predetermined body portion) are called protostomes after the coelom formation of mouth. The spiral cleavage undergoes determinate cleavage where the coelom splits(schizocoely). Deuterostomes embryonic cells undergo indeterminate cleavage, and forms radial cleavage where the coelom outpockets(enterocoely).