This draws in sediment and amphipods from the ocean bottom. The whale then pushes the sediment through the baleen plates on the opposite side of its 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 route of any mammal.
Each year they cover more than 9,000 km travelling 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 80 km each day-often close enough to shore that they can be sighted from land. B.C. summer resident whales do not visit Arctic waters. Warm winters Gray whales spend winters, from January to March, in the warm waters of Baja California, Mexico, where pregnant females give birth. By late February, they start swimming northward.