Dolphins have grey skin that can be different colors, with sleek bodies and no hair. They rely heavily on hearing, which is 7 times better than humans, and tasting water to navigate as they are believed to lack a sense of smell. Dolphins mainly eat fish and squid, though different species prefer different types of food. As warm-blooded mammals, dolphins can reach speeds of over 26 km/hr and leap constantly, and their long noses help them kill sharks.