Mammals are members of class Mammalia, air-breathing vertebrate animals characterized by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young. Most mammals also possess sweat glands and specialized teeth. The largest group of mammals, the placentals, have a placenta which feeds the offspring during gestation. The mammalian brain, with its characteristic neocortex, regulates endothermic and circulatory systems, the latter featuring red blood cells lacking nuclei and a four-chambered heart. Mammals range in size from the 30–40 millimeter (1- to 1.5-inch) bumblebee bat to the 33-meter (108-foot) blue whale.
The word "mammal" is modern, from the scientific name Mammalia coined by Carl Linnaeus in 1758, derived from the Latin mamma ("teat, pap"). All female mammals nurse their young with milk, which is secreted from special glands, the mammary glands.
Except for the five species of monotremes (which lay eggs), all living mammals give birth to live young. Most mammals, including the six most species-rich orders, belong to the placental group. The three largest orders, in descending order, are Rodentia (mice, rats, porcupines, beavers, capybaras, and other gnawing mammals), Chiroptera (bats), and Soricomorpha (shrews, moles and solenodons). The next three largest orders, depending on the classification scheme used, are the primates, to which the human species belongs, the Cetartiodactyla (including the even-toed hoofed mammals and the whales), and the Carnivora (cats, dogs, weasels, bears, seals, and their relatives).
Quick Facts on Mammals
1. Mammals are animals that have skin covered with hair.
2. Mammals are viviparous – young are born alive.
3. Mother mammals nourish their babies with milk thru
4. Mammals are heterodonts – have a variety of specialized
teeth (incisors, canines, premolars, and molars) and strong
5. Most mammals are placental – the embryo develops internally
in a uterus to the mother by a placenta.
6. Some are marsupial – in the very early part of the embryonic
development the young are born and completes its
development in the mother’s pouch
7. One very unusual is the duck-billed platypus is monotreme –
its egg laying.
8. Many mammals are terrestrial.
9. Others are aquatic.
10. A few are aerial.
11. Some are domesticated.
12. Others are wild.
13. Mammals are the only animals with an outer ear just like the
14. Pandas eat lots of bamboo up to 12 hours everyday.
15. Moose are the biggest of all the deer.
16. Despite the hump, a camel’s spine is straight.
17. Porcupines float in water.
18. A cat’s jaws cannot move sideway
19. Koala sleeps 20 hours each day.
20. Bats are the only flying mammals.
21. Kangaroos cannot walk backwards.
22. Chimps are the only animals that can recognize themselves in
23. Elephants have been known to remain standing when they
24. Giraffes are the tallest animals.
25. Cheetahs are the fastest animals.
26. A zebra is white with black stripes.
27. Armadillos can walk underwater.
28. Blue whale is the largest animal that lived on earth.
29. Only humans can sleep on their backs.