Decades of commercial whaling nearly decimated a variety of species of whales. These intriguing animals, which capture humans' imagination, are a keystone species. They and other keystone species are indicators of the overall health of Earth's habitats. While whales have made a comeback through an international ban on commercial whaling, they are still threatened with extinction. In fact, two whale species - the Cook Inlet beluga whale and the Southern Resident killer whale - are endangered.
