* Warm-blooded: They regulate their own body temperature.
* Hair or fur: They have some form of hair or fur covering their bodies.
* Give birth to live young: They do not lay eggs.
* Feed their young with milk: They have mammary glands that produce milk to nourish their offspring.
Here are some examples of different mammal groups:
Placental mammals: These are the most diverse group of mammals and include:
* Primates: Monkeys, apes, humans, lemurs
* Carnivores: Dogs, cats, bears, wolves, seals, etc.
* Rodents: Rats, mice, squirrels, beavers
* Ungulates: Horses, cows, deer, pigs
* Cetaceans: Whales, dolphins, porpoises
* Bats: The only mammals that can fly
* Elephants: Large, trunk-bearing mammals
* Many, many more!
Marsupials: These mammals give birth to very underdeveloped young that continue to develop in a pouch on the mother's belly.
* Kangaroos: Large, hopping marsupials
* Koalas: Tree-dwelling marsupials
* Opossums: Found in the Americas
* Wombats: Burrowing marsupials
Monotremes: These mammals lay eggs.
* Echidnas: Spiny anteaters
* Platypuses: Duck-billed, egg-laying mammals
This is just a small sampling of the incredibly diverse world of mammals. If you're interested in learning more about specific mammals, just ask!