A feeding gray whale turns so that one side of its mouth faces the ocean bottom. When the whale opens its mouth slightly and pulls in its huge tongue, it draws in sediment and amphipods from the ocean bottom and pushes the sediment through the baleen plates on the opposite side of the whale's mouth. The amphipods are caught in the baleen - which acts like a filter. Scientists think they can tell whether a gray whale is a right or left handed feeder by looking at barnacles and scraped skin. There are more skin scratches, and fewer barnacles, on the side of the whale that faces the bottom when it feeds.
Gray whales have the longest migration of any mammal.
Each year they cover more than 9,000km traveling between their summer feeding areas and their winter breeding lagoons. Navigating by following the contours of the sea floor, migrating gray whales travel 60 to 80km kilometres each day - often close enough to shore that they can be sighted from land. By mid-February, they start swimming northwards. Adult males, newly-pregnant females and juveniles leave first, followed by females and their calves. Some gray whales start feeding when they reach the waters along Vancouver Island, British Columbia.