Caribou are members of the deer family who were once widely distributed across much of North America. These large animals have played an important economic role in Canada and Alaska, where they are still reasonably abundant, and many people enjoy seeing herds in the wild when they visit these regions. Along with other arctic animals, caribou have developed a number of unique traits which make the animal especially suited to life in the harsh arctic environment.
There's actually no difference between these animals and reindeer. Caribou is simply the North American name for the reindeer; it is derived from the Micmac Indian language. However, there are a few genetic differences between European and North American reindeer which have led biologists to classify them into different subspecies. Both of these animals are considered Rangifer tarandus, but the North American subspecies are not found in Europe, and the European subspecies are not found in North America. Several subspecies have also gone extinct.
One North America subspecies, the woodland caribou, was once widely found in the forests of Canada and parts of the Northern United States. They have short, heavily branched antlers, in contrast with the larger curved antlers of the barren ground caribou, found in the tundra of the arctic. It's also possible to spot Grant's caribou and peary caribou in some parts of North America.
As a general rule, these animals are gray to brown in color, with a thick undercoat of insulating hair and a longer overcoat of hollow hairs used to trap heat. Adults can weigh as much as 660 pounds (300 kilograms), with females typically being much smaller. Along with their heat-trapping coats, caribou have developed several other interesting adaptations to help them survive in the arctic. For example, their nose is extremely large, with a lot of internal surface area, allowing air to warm before it is drawn into the lungs, and they can modifying their hooves to deal with seasonal changes.
Like their European counterparts, caribou have historically been used as draft animals, hunted for food, and domesticated for milk. Whether domesticated or wild, caribou live on a diet of lichen, spring growth from plants, and grasses. In winter, the ability to survive on lichen alone becomes especially important, as green growth is very scarce.