Delphinds are found in all oceans and seas and in some river systems. They generally live in shallow water or at least stay near the surface, not making the deep and prolonged dives that characterize some other groups of cetaceans. They are fast and acrobatic swimmers, feeding on fishes and squids, which they pursue actively. Killer whales also prey on mammals such as other cetaceans and pinnipeds, as well as on birds and large fish. Like other odontocetes, delphinids echolocate and may even use high-intensity sound to stun their prey.
Individuals appear to cooperate in a number of ways.
One example is that these schools sometimes attack sharks, killing them by ramming them. Dolphins may work cooperatively to assist an individual that is ill or injured. Groups of dolphins often follow ships, riding the bow wave and sometimes making spectacular, acrobatic leaps. Several individuals in a school may leap in concert. Delphinids appear to be highly intelligent, adapting quickly and flexibly to novel situations.