Gray whales carry whale lice and parasitic barnacles that look like crabs. These parasites create yellow and white patches on the whales. Instead of a dorsal fin, gray whales have 9-13 bumps along their dorsal ridges. It is thought that gray whales probably have excellent hearing, especially at low frequencies, which is valuable in the dark ocean environment where vision is less useful. Gray whales filter their food through coarse baleen plates.
Gray whales are unique in that they prefer prey that live near or on the sea floor.
They suck sediment and prey from the sea floor by rolling on their sides and swimming slowly along sucking sediment and prey from the sea floor. Gray whales are probably old enough to mate around 8 years old. Females are pregnant for about 13 months approximately every two to four years. Calves are born able to swim and are known to double their weight in about three months, and double their length in about two years. A mother and calf form a very close attachment, with the calf spending the majority of its time swimming close to its mother.