Animals of the World: M

Mammals are a group of animals defined by features such as hair or fur, the ability to nurse their young with milk, and being warm-blooded. They range from tiny shrews to the great whales, and they live in nearly every habitat on Earth. Many of the animals people know best, including primates, hooved grazers, and large predators, belong to this group.

Monkeys are primates, the group of mammals that also includes apes and, ultimately, humans. They are typically agile, intelligent animals with grasping hands, and many are adapted to life in trees, where a long tail can aid balance or grip. Primates tend to have forward-facing eyes that give good depth perception, useful for moving through branches and judging distances.

Other notable mammals include the rhinoceros, a large, thick-skinned hooved animal bearing one or two horns, several species of which are endangered because of habitat loss and hunting. Deer are graceful hooved animals in which the males usually grow and shed antlers each year. Together these animals show the range of the mammal group, from agile climbers to heavy grazers, and many are now protected to prevent their decline. Because mammals nurse and often care for their young for an extended period, many species also pass learned behavior from one generation to the next.

Frequently asked questions

What features define a mammal?

Mammals are warm-blooded animals that have hair or fur and nourish their young with milk. Most give birth to live young.

Are monkeys the same as apes?

Both are primates, but they are distinct groups. Monkeys usually have tails, while apes do not, and apes are generally larger.

Why are some rhinoceros species endangered?

Rhinos have declined mainly because of habitat loss and hunting for their horns, and several species now survive only in protected areas.