Eschrichtius robustus, commonly known as the gray whale, is a large marine mammal found primarily in the North Pacific Ocean. They can grow up to 50 feet long and weigh up to 40 tons. Gray whales are known for their long migrations, traveling between feeding grounds in the Arctic and breeding grounds in warmer waters, such as those off the coast of Mexico. These whales are unique for their bottom-feeding behavior, using their baleen plates to filter small organisms from the sediment. Gray whales are also known for their distinctive gray coloration and the barnacles that often attach to their skin. They are classified as a species of concern due to past whaling practices and current environmental threats.