Dolphins from the Delphinidae family, which are the oceanic mammal family, have over thirty species in their family including five that live in rivers. Different species of this family feed on various fish such as herring, mullet, cod, salmon, squid, anchovies, mackerel and flying fish. Found in the coastal waters and off shore in every ocean in the world many dolphins are known to live in schools of several hundred but some prefer to live alone. Predators of the dolphins include most sharks and the killer whales. It is not uncommon when the dolphin cannot speed away from its predator to see others of its kind attacking the predator by battering it until it dies.
Dolphins mate in the spring, with the females producing a single calf during the following spring.
Most species are known to be very protective of their group, even helping protect those who are sick to the surface to breath. The genera of river or fresh water dolphins have smaller eyes and very poor vision with most found in Asia and South America. Of the Delphinidae family, the bottle nose dolphin is the most widely recognized by humans. This is the dolphin that is often seen in captivity due to its playful attitude and friendliness toward humans. The bottle nose dolphin has been studied extensively and is the subject of movies, art and many different forms of literature.