CategoryHierarchies.com

Mammals, reptiles, birds, and fish are all types of animals that fall under the classification of vertebrates. Mammals are warm-blooded animals that typically have hair or fur, give live birth, and nurse their young with milk. Reptiles are cold-blooded animals that are covered in scales or tough skin, lay eggs, and have a dry, scaly skin. Birds are warm-blooded animals with feathers, lay hard-shelled eggs, and have the ability to fly in most cases. Fish are cold-blooded animals that live in water, breathe through gills, and have scales covering their bodies. Each of these groups has unique characteristics that distinguish them from one another.