About Mammals
Mammals are a class of vertebrate animals (animals with backbones). They are different from other animals (like reptiles and arachnids) by the mammary glands in which mothers produce milk for the nourishment of her young; the presence of hair or fur; and which have endothermic or "warm-blooded" bodies (bodies that maintain a constant temperature). The brain regulates the endothermic and circulatory systems which includes a four-chambered heart. The mammals class encompasses some 5500 species. That's a lot of mammals!Mammals are divided into three broad subclasses (which are then divided down to specific species):
- Marsupials: Mammals that give birth to undeveloped young that are then raised in pouches until maturity. eg. Kangaroos, Koalas, Wombats
- Monotremes: Mammals that lay eggs. eg. Platypus
- Placentals (largest group): Mammals that give birth to fully developed young. eg. Whales, Lions, Cats
Some common mammals are dolphins, chimpanzees, dogs, bats, bears, lions, beavers, blue whales, camels, sea lions, coyotes, deer, foxes, squirrels, girraffes, horses, orcas, panda bears, rabbits, mice, sheep, otters... and, of course, humans!
(Thanks to Kell for the summary!)