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What are mammals?

Greater white-toothed shrew. Its body length is no more than 9 cm (3.5 inches).Mammals are warm-blooded animals. They feed their newborn young with milk and protect them from danger during the earliest part of their lives. Most mammals develop inside the mother, instead of hatching from eggs. Except for some sea mammals, they all have four limbs and are covered with hair or fur. There are about 5000 species of mammal living on the land, in the water or in the air. They range in size from tiny shrews to giant blue whales. Mammals are the group of animals to which humans belong.


Blue whale, up to 30 m (100 ft) long

A sambar deer scent marking. Deer produce a strong scent called a pheromone. The use it to mark their territory by rubbing it...Read More >>A sambar deer scent marking. Deer produce a strong scent called a pheromone. The use it to mark their territory by rubbing it against tree branches or trunks. (Hunters are able to track deer by spotting their "rubs".)

Senses

Mammals have large brains and highly developed senses. Human eyes can see in great detail and in a wide range of colours. With its superb hearing, a dog can detect sounds far higher in pitch than humans can, and hear sounds much further away.
A number of mammals rely on their sense of smell. A dog's is up to 40 times more sensitive than a human's. Scent may be used to mark the borders of a mammal's territory, or to detect an approaching predator.

The longest-living mammal is the bowhead whale. In 2007, one was discovered to have a harpoon dating from 1880 stuck in its neck. It was therefore at least 130 when it died in 2010. Scientists think bowheads may actually live for up to 200 years.

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