Vertebrate Classes

A mammal (from Latin mamma 'breast') is a vertebrate animal of the class Mammalia ().

Birds are vertebrate animals constituting the class Aves, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton.

Reptiles, as commonly defined, are tetrapod vertebrate animals with an ectothermic metabolism and amniotic development.

Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia.

Actinopterygii ( ; from Ancient Greek ἀκτίς (aktís) 'ray, beam' and πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that constitutes nearly 99% of the over 30,000 living species of fish.

Chondrichthyes (; from Ancient Greek χόνδρος (khóndros) 'cartilage' and ἰχθύς (ikhthús) 'fish') is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage.

Cyclostomi, often referred to as Cyclostomata (, from Ancient Greek κύκλος (kúklos), meaning "circle", and στόμα (stóma), meaning "mouth", and thus, "circular mouth") is a superclass of vertebrates that comprises the living jawless fish classes: the lampreys and hagfishes.

Sarcopterygii (; from Ancient Greek σάρξ (sárx) 'flesh' and πτέρυξ (ptérux) 'wing, fin') is a clade (traditionally a class or subclass) of vertebrate animals which includes a group of bony fishes and all four legged land animals, including humans.

Hagfish, of the class Myxini (also known as Hyperotreti) and order Myxiniformes , are eel-shaped jawless fish (occasionally called slime eels).

Agnatha (; from Ancient Greek ἀ- (a-) 'without' and γνάθος (gnáthos) 'jaws') or jawless fish is a paraphyletic infraphylum of animals in the subphylum Vertebrata of the phylum Chordata, characterized by the lack of jaws.