The dolphins abilities to be trained, their intelligence, the memory and the way of coagulation of their blood has made a big interest for researchers. It is necessary to create a oceanaria for them, because it is much harder to research them in freedom. They posses strong abilities to learn, have a long time memory and does not imitate the gestures like other animals when they are trained, and establish links between movements, sounds and trainer intentions. There was situations when the dolphins requests help to peoples and they help them when need it and when they were there. The dolphins had evolve for 50 millions years when they were terrestrial animals, and are related with current hippopotamus. There are over 73 dolphins species. When they haunt or explore, the dolphins sends ultrasounds for guidance and it is possible to use magnetic field of the Earth on long voyage. A 120 kilos dolphin has 1.7 kilos of brain and a human brain has 1.4 kilos. The dolphin brain is not only big, but complex too. The way they are swimming is made on any direction (front, back, left, right, up and down) and are using a big speed. They have capacity to percept frequencies that not even peoples can, from a few hertz to 200 KHZ. Having a complex social system, they haunt in groups and spend time together very much. They have many perception of sound dialects, that make them to not understand each other between different populations. They live between 30 and 40 years.