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Vertebrate classes

Vertebrate classes
Class orders
Diagrams and bibliography

The 7 living classes of vertebrates are distinguished mostly on the basis of their skeletal system, general environmental adaptation, and reproductive system.
The 7 living classes include:
Agnatha, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia.

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 and rays.
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.