About Mammals

Mammals are among the most adaptable animals on the planet.

They are found on every continent and in every ocean, and range in size from tiny bumblebee bats to enormous blue whales. One reason for their success is the way they move. Mammals as a group use every possible form of locomotion. Terrestrial species walk, run, jump, climb, hop, swing, dig, and burrow. Aquatic ones swim, shuffle, and dive. A few even fly.

Diet and behavior vary, too. Many carnivores, for example, are top predators that live generally solitary lives. These include jaguars, tigers, and polar bears. By contrast, lions, otters, wolves, and dolphins live in family groups. Even more social are some of the herbivores, especially hoofed animals like deer and zebra. By living in large groups, they gain both protection against becoming another animal’s meal and more opportunities to breed. Among omnivores, primates are known for their high intelligence, and rodents for their high numbers.

Mammal bones, especially skulls, are used for identification, and to work out the evolutionary history of each species. The jaws of a house cat are more lion- than wolf-like, for example. The teeth of horses and zebras look alike. The ear bones of mammals were once the jaws of prehistoric reptiles. And so on.

Despite these differences, all mammals share four traits that are shown in the diagram below: hair, mammary glands, a hinged jaw, and three tiny middle ear bones. Most have specialized teeth and moveable external ears.

From the National Geographic book, Animal Encyclopedia, 2012

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We head away from land onto the ice floes of the Gulf of St. Lawrence, where thousands of harp seals are giving birth to tiny yellow pups. The adults have come so far south from their feeding grounds that this forms a unique oasis away from their main predator, the polar bear. But there’s a catch. From the minute the pups are born, they enter a race against time. In one of the shortest mammal weaning periods, the pups have just 10 days to drink all the milk possible and start swimming before their mothers abandon them on melting ice. Our changing climate means the stakes couldn’t be higher. If the ice melts before they learn to swim, this generation of pups will drown. The visuals in this episode are magical, with unbelievably cute pups peppered across the ice. This story is a unique opportunity to get up close and personal with ice, both above and below the surface. This episode will ultimately bring to life the message of the entire series: We are all inextricably tied to sea ice.
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