The lower jawline is deeply curved upwards in profile. Encrusting growths, called callosities, on the head, jaws, and blowhole areas of right whales are yellow-white. Accumulations of natural markings such as these aid researchers in photo-identification studies. Rorquals have a broad, flat rostrum and a slightly curved jawline. Humpback whales have several knobs on their heads.
Gray whales have a narrow head with a slight curve to the jawline.
The neck vertebrae are unfused in rorquals and gray whales, which allows for some flexibility at the head and neck. Blowholes are covered by muscular flaps. These flaps provide a water-tight seal. This prevents water from entering the blowholes upon surfacing to breathe. Each blowhole leads to an air passage that leads to a baleen whale's trachea and then to its lungs.