All kinds of creatures that live on earth, from each kind or group have mutual emotions and these emotions relate to size of brain and way of living. Style of living in every creature influences on feeling, loving, violence and communicating with the world around directly. Besides, territory is very important too. | Among marine organisms, there is an animal, name dolphin which has special features. After intercourse they become pregnant and after giving birth feed newborns by milk. This aquatic get used to live in water. Dolphin’s main foods are fishes and cephalopods. Dolphins have a different brain in compare with other marine mammals. This causes that they can save events in their short term and long term memory. This ability makes them sociable creatures so that they live in small or big groups. Group life among dolphins comes from their demand to decrease hunting by enemies. Also dolphins show some signs of culture among themselves. Sometimes they show aggressive behaviors since they look for gaining opposite sex. Most of them are bigamy. Their genital organs locate on lower part at the end of body. They have sex by sticking their bellies and would be many times in a short time. One of the most important behaviorsamong dolphins is their suspicious suicide. There are a lot of theories about this behavior including depression, changing generation by old dolphins, water pollution of the seas, too traffic of military and non-military ships and other unscientific reasons. The important point about dolphin’s death is that they arrive to seashore dead and something that is certain is dolphins’ extinction but scientists don’t declare a given date for this phenomenon.