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 belt slippage, and are often used to transfer motion for indexing or timing purposes (hence their name). They are often used in lieu of chains or gears, so there is less noise and a lubrication bath is not necessary. Toothed belts are used widely in mechanical devices, including sewing machines, photocopiers and many others. A major use of toothed belts is as the timing belt used to drive the camshafts within an automobile or motorcycle engine. As toothed belts can deliver more power than a friction-drive belt, they are used for high-power transmissions. These include the primary drive of some motorcycles,