English Across the Curriculum

The World of Mammals


A mammal is an animal that feeds its babies with milk when it is young. There are over 4,500 types of mammals. Many of the most popular animals we know are mammals, for example, dogs, cats, horses, cows, but exotic animals like kangaroos, giraffes, elephants and anteaters belong to this group, too. Humans are also mammals.

Mammals live in all regions and climates. They live on the ground, in trees and even underground. Polar bears, reindeer and seals are mammals that live in the Arctic regions. Others, for example camels or kangaroos, prefer the world's dry areas. Seals and whales are mammals that swim in the oceans; bats are the only mammals that can fly.

Colony of seals
Image: M. Boylan [Public domain]


Mammals have five features that make them different from other animals:

  • Female mammals produce milk and feed their babies with it.
  • Only mammals have hair or hair-like skin. All mammals have hair at least some time in their lives.
  • Mammals are warm-blooded. Their body temperature always stays the same and does not change with the outside temperature.
  • Most mammals have a larger and well-developed brain. They are more intelligent than other animals.
  • Mammals protect their babies more than other animals. They prepare them for future life.

Pigs sucking milk from their mother
Image : Wiki.cullinCC BY-SA 4.0, via Wikimedia Commons

People have hunted mammals for ages.They ate their food and made clothes out of their skins. Thousands of years ago wild mammals were domesticated and gave human beings milk, wool and other products. Some mammals, like elephants and camels, are still used to transport goods. In poorer countries farmers use cows or oxen, to plough fields.

Animals ploughing fields in India
Image: ©Yann Forget - Wikimedia Commons


Today some mammals are hunted illegally. Whales are killed because people want their meat and oil, elephants are killed for their ivory and tusks.

Mammals are often kept as pets. Among them are cats, dogs, rabbits or guinea pigs.

Mammals are useful to people in many other ways. Some help plants grow and eat harmful insects. Others eat weeds and prevent them from spreading too far. The waste of mammals is used as fertilizers that improve the quality of soil.

Tusk of an African elephant
Image: Taken by Schuyler ShepherdCC BY 2.5, via Wikimedia Commons