Information about Mammals:
Mammals are animals characterized by being warm-blooded, air breathing animals with a vertebrate or backbone. They also have hair, three middle ear bones and mammary glands the mother uses to feed the young. Along with this, most mammals have sweat glands, and possess specialized teeth. There are thought to be about 5,500 mammals on the planet, depending on how the animals are classified.
Mammals evolved slowly over time from four-legged predecessors. Their limbs are used to walk, climb, swim, and fly. Some land mammals have toes that produce claws and hooves for climbing and running – and these are called ungulates. Marine mammals such as whales and dolphins developed from animals that had evolved from the sea and onto land, then gradually evolved back into a marine environment.
Generally, mammals are endothermic, which means that their body temperature is self regulated, rather than dependent on the conditions of the surrounding environment. What this means is that their bodies remain at a certain base temperature – generally around 98-100 degrees – regardless of how hot or cold their environments are. The largest mammal on the planet is also the largest animal to ever live on the planet: The Blue Whale. The smallest mammals is believed to be the Bumble-Bee Bat which in only about 1-1.5 inches long.