Cetacea and two (external) limbs that are modified into flippers. Though not as flexible or agile as seals, cetaceans can swim very quickly, with the killer whale able to travel at in short bursts and the fin whale able to cruise at . Dolphins are able to make very tight turns while swimming at high speeds. The hindlimbs of cetaceans are internal, and are thought to be vestigial. Baleen whales have short hairs on their mouth, unlike the toothed whales. Cetaceans have well-developed senses—their eyesight and hearing are adapted for both air and water, and baleen whales have a tactile system
Toothed whale and cone cells, meaning they can see in both dim and bright light. They do, however, lack short wavelength-sensitive visual pigments in their cone cells, indicating a more limited capacity for colour vision than most mammals. Most toothed whales have slightly flattened eyeballs, enlarged pupils (which shrink as they surface to prevent damage), slightly flattened corneas, and a tapetum lucidum; these adaptations allow for large amounts of light to pass through the eye, and, therefore, a very clear image of the surrounding area. In water, a whale can see around ahead of itself, but they have a smaller range above