Dolphins are cetacean mammals, they are related to whales. You can find them in shallow seas of the continental shelves. There are 17 different species of Dolphins, and their size is from 1.2m and 40kg of weight up to 9m and 10 tons (orca whale).
Dolphins are adapted for fast swimming, they have slim bodies and there is no hair (most mammals have hair). Something unique about them is the existence of a special organ in their head. It is called melon, purpose of this organ is echolocation. It is more advanced than any sonar men ever built. They breathe using blow-hole, at the top of their head. It means that they must come out on the surface to take in air.
Studies have shown us that Dolphins can also develop type 2 diabetes, which is important for better understanding of this disease. They have very good power of regeneration. It allows them to fully recover from severe injuries, usually made from sharks. Although, some injuries are so deep, Dolphins never bleed to death. Scientists still don’t know how this regeneration possibility really works. Another advantage is their hearing sense, it allows them to hear frequencies that are 10 times upper then the limits of humans hearing sense.
They usually hunt in large groups, hunting fish and squid, using their sonar. In some cases the often strand at the shores and die, if help isn’t provided to them.
They are commonly known because their jumping above water. Reasons why they are doing that are: orientation, entertainment, to speed up, fighting and to remove parasites on their body. Because their high intelligence, Dolphins usually consider as the smartest animals on the planet.