Dolphins and sharks inhabit the same regions and depths of the oceans. Sharks have a reputation as fierce predators, armed with rows of sharp serrated teeth that can bite through flesh and bone with ease. Sharks have a very tough, sandpaper-like skin that is not easily punctured. Dolphins are seen as intelligent, playful mammals with only a single row of peg-like teeth used mainly for catching smaller fish. Their skin is soft, flexible and can be cut easily. Dolphins are sometimes seen protecting an injured or sick member of their group, which is often a member of their extended family, from shark attacks. Dolphins have even been known to protect humans from sharks in the water and even carry people safely to shore.
Though at first glance sharks and dolphins seem similar in size and shape, there are many differences between them. Sharks are an ancient order of fish, with skeletons of cartilage. Dolphins are descended from mammals that have returned to the sea, and they have skeletons with hard calcified bones. The skeletons of sharks have joints that are not as flexible as the dolphins'. Dolphins are much swifter than sharks and can maneuver very quickly and agilely in the water. The tail of a dolphin and a shark are also different. A shark's tail has fins on a vertical plane that move from side to side, which limits its ability to quickly dive downward or rise upward . A dolphin's tail has horizontally mounted flukes that move up and down, which enables a dolphin to easily change direction upward or downward in the water.
Since dolphins normally travel together in a group, if one of them is threatened by a shark, the other members of the group will join in to defend the dolphin that is in danger. The dolphin's main weapon is their snout, which is made of very strong and thick bone, and has a hard, rounded end. The dolphins circle the shark very rapidly from different directions, which causes the shark to become confused and unable to chase any one of the dolphins. When a dolphin is positioned below a shark at a distance of several yards, the dolphin will make a suddenly rush at the shark's softer underbelly and ram it with his snout. The effect is like an extremely powerful punch. The shark can be seriously injured with a single blow, and they are often stunned or knocked unconscious. The dolphins will sometimes repeatedly ram a shark that has been very aggressive, and will often kill a large, dangerous shark.