The characteristics of each class:
Agnatha consists of jawless fish that do not have scales which are the
lampreys and hagfish.
Chondrichthyes are vertebrates that have rough cartilage rather than bone, such as sharks
Osteichtyes are bony fish, such as tuna, bass, and salmon.
Amphibia spend part of their time on land and part of their time in water. Examples of amphibia
are frogs, toads, and salamanders.
Reptilia such as snakes and lizards have lungs to breathe on land and skin that does not need
to be kept wet.
Aves includes all birds who produce amniote eggs and give them great protection from predators.
Mammalia are all mammals that conceive young who are nourished with milk from mammary glands.