Mammals range in size from the pygmy shrew, which weighs less than a dime, to the blue whale, which weighs more than 100 tons (101,606 kilograms). Mammals live almost everywhere, from steaming rain forest to the frozen Arctic, from arid desert to the open oceans. Most live on the land surface though some burrow beneath it, some live in trees, and a few -- the bats -- can fly. Others spend part or all of their time in water.
What is a mammal? Mammals can be identified by certain characteristics that they all possess.
Mammals are part of a group of animals called vertebrates, along with fishes, amphibians, reptiles, and birds. Vertebrates are animals with a backbone and an internal skeleton for support. With few exceptions, birds and mammals are the only animals capable of controlling their body temperatures. The scientific term for this is endothermy. Using internal controls, most mammals can maintain their body at about the same temperature even when the temperature around them changes (within limits). Endothermy permits animals to be active regardless of the air temperature and allows birds and mammals to remain active during times when or in areas where it would be too hot or too cold for other animals to function.
All mammals (and only mammals) have hair. The main function of hair is insulation, although it is often colored for use in camouflage or display, is sometimes adapted as a sense organ (for example, whiskers), and is even modified for protection (for example, rhinoceros horn).
Nearly all mammals give birth to live young. An important characteristic of mammals is that every female mammal feeds her young on milk from her body. The word mammal comes from the Latin word mamma, which means "breast." Mothers produce milk in mammary glands; only mammals produce milk.
Mammals have only four kinds of teeth but these are variously adapted in different groups for eating many different types of food. The differences in their teeth provide a useful means for classifying related groups of mammals.
A habitat is the particular environment where a plant or animal lives - its neighborhood. Many different species of mammals live in the diverse habitats of Africa. Each kind is adapted (suited) to a particular way of life. Animals, like plants, have special adaptations to help them survive in their habitat. The design and function of an animal's body tell a lot about its way of life and where it lives. In mammals, the teeth and limbs are especially useful in signaling the kind of habitat in which the animal lives. In addition, the physical and biological elements of a habitat determine what animals will be found there.
As you look at a mammal, think about where it lives. What is the vegetation Iike? Is it dry or wet? Is it hot or cold? What are the reptiles, birds, and insects that live with it? What does the mammal eat?
By knowing the habits and habitat of an animal, you will be able to locate where it lives. Some animals live only in a very particular type of habitat. Other animals are not as specific in their living requirements and inhabit many different types of habitats. What type of habitats do people live in? What do people eat?
Let's take a look at the chimpanzee, which makes its nest in trees. It eats the fruit, leaves, bark, and seeds of trees; it also eats insects and other items. The chimpanzee has long arms and hands designed to climb trees and swing from branch to branch and tree to tree in a forest.
Living in family groups helps protect young or sick chimpanzees from its enemy the leopard. Look at the map where the chimpanzee is found in Africa (its range). Compare the map to the vegetation map. The chimpanzee is found only in forests, where there are abundant trees to provide food and shelter.
The leopard eats many other animals besides the chimpanzee. It is adaptable, found in many habitats from desert to rain forest, wherever there are enough animals to eat.
The secretive okapi and bongo dwell only in the dense tropical forests. The deep brown color of their coats, striped with white, hides the animals well in the play of light and shadows on the forest floor.
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