Polar bears are the largest bears in the world and the Arctic's top predator. At birth, they are the size of an adult guinea pig. When fully grown, males usually measure about eight to nine feet nose to tail, and females are about six to seven feet long. And their feet are each the size of a dinner plate—about a foot wide!

Sloths are famous for moving slowly in the tree canopy. It surprises many to learn that sloths are strong swimmers. They will sometimes drop down from their treetop perches into water and use their lengthy arms to propel through the water.

Known more for its jump, the jaguar can reach speeds of up to 50 miles per hour for a short distance. These cats—the largest in the Americas—are also strong swimmers and climbers.

Often dubbed the unicorns of the sea, narwhals are strange and beautiful Arctic creatures with long spiraled tusks protruding from their heads. The narwhal tusk is actually an enlarged tooth with sensory capability and up to 10 million nerve endings inside. Some narwhals have one or two tusks, while others have none. Tusks can grow as long at 10 feet.

Tigers are mostly solitary, but when they come together the group is called a streak—or an ambush! Individual tigers have a large territory whose size is determined mostly by the availability of prey. These cats rely primarily on sight and sound rather than smell for hunting.

The island of Borneo is the world's third largest island and home to some of the world's most biologically diverse rain forests—and Bornean elephants, found only in the northeastern part of the island. Bornean elephants, also knows as pygmy elephants, are distinctly smaller than their mainland cousins. They have long tails that sometimes touch the ground, relatively large ears, and straighter tusks. There may be fewer than 1,500 Bornean elephants left.

A single generation performs the incredible feat of migrating from Southeast Canada and the Northeast United States to central Mexico to hibernate during the winter. At the beginning of spring, the same generation starts the return migration all the way to Texas, where they lay their eggs. The next three to five generations will continue to fly North to complete their journey.