Both males and females weigh up to 30,000 kg. These big animals eat large quantities of tiny animals. Scientists think an adult gray whale consumes about 1,200 kg of food per day. The main component of their diet is small, shrimp-like animals called amphipods that live on muddy ocean floors. Amphipods are tiny compared to gray whales.
Gray whales use suction to draw food into their mouths.
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.