In the summer, they travel to the Arctic or Antarctic regions and feed on abundant supplies of plankton. Plankton is clumps of small plant and animal life that drifts on the surface of the ocean. In the winter, the whales migrate thousands of miles to the warmer tropical oceans near the equator. Most toothed whales do not migrate. Killer whales are the top predators in the ocean.
Whales are from a group of mammals called cetaceans.
All whales belong wo two main cetacean groups. The blue whale is the largest animal ever to exist on earth. Three main populations of gray whales once existed in different parts of the world. There was a large population of gray whales in the North Atlantic that was hunted to extintion by about 1700. There was a Korean population in the northwest Pacific that was hunted until 1968 and is now rare.