Humans are categorized as vertebrates in the phylum Chordata. The phylum Chordata contains all animals that possess, at some point during their lives, a hollow nerve cord, and a notochord, a flexible rod between the nerve cord and the digestive track. The phylum Chordata is an extremely diverse phylum and the one most recognizable to us.
A. Amphibians are the cold-blooded, freshwater vertebrates which can live both on land and in water.
B. Osteichthyes is the class of bony fishes which include lungfishes, ray-finned fishes and lobe-finned fishes.
C. Chondrichthyes is a class of Cartilaginous fishes which include sharks, rays and Chimaeras.
D. Cyclostomata is a class of round mouthed fishes under the superclass Agnatha which is known as Jawless vertebrates. The digestive system of Cyclostomata lacks stomach and pancreas.