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 Birds are warm-blooded vertebrates (vertebrates have backbones) and are the only animals with feathers. Although all birds have wings, a few species can't fly. 

 Mammals include humans and all other animals that are warm-blooded vertebrates with hair. They feed their young with milk and have a more well-developed brain than other types of animals.   

 Reptiles are cold-blooded vertebrates. They have dry skin covered with scales or bony plates and usually lay soft-shelled eggs. 

 Fish are vertebrates (vertebrates have backbones) that live in water. They breathe using gills. 

 Amphibians are cold-blooded vertebrates that don’t have scales. They live part of their lives in water and part on land. 

 Invertebrates are animals without a backbone or bony skeleton. They range in size from microscopic mites and tiny flies to giant squid with big eyes.