The dolphin is a marine mammal belonging to the cetacean order. An excellent swimmer, it has lungs and can hold its breath for 20 minutes under the water. The small hole on its head known as the spiracle enables it to take in oxygen on the water’s surface. It is also capable of diving to great depths. This is a very sociable animal which mainly lives in groups (from 15 to more than several hundred according to the species). This is a definite advantage where protection from predators is concerned but also for hunting shoals of sardines or mackerel. Dolphins emit ultrasound and use echo-location (a kind of sonar) to find their way around and to detect the presence of obstacles or shoals of fish. They like to play and often display their joy with incredible leaps from the water.