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Dolphins have a pair of pectoral fins behind the head, which they use for steering.  Primary propultion comes from the tail, which bears horizontal flukes made from subcutaneous dermal tissue; movement through the water consists of vertical sweeps of the tail.  Speeds of dolphins have been estimated at  23-25 mph (37–40 km/h), which is enough to allow for “porpoising” i.e. the leaping of the animal out of the water at various times.  Some species have been observed to reach higher speeds.

Dolphins have a pair of pectoral fins behind the head, which they use for steering.  Primary propultion comes from the tail, which bears horizontal flukes made from subcutaneous dermal tissue; movement through the water consists of vertical sweeps of the tail.  Speeds of dolphins have been estimated at  23-25 mph (37–40 km/h), which is enough to allow for “porpoising” i.e. the leaping of the animal out of the water at various times.  Some species have been observed to reach higher speeds.

Most species of dolphins also bear a dorsal fin on their backs, made from the same dermal tissue as the tail flukes, and is believed to act as a stabilizer while moving.  In some species (orca, grampus), the dorsal fin is rather large relative to the size of the body; in several others the fin is a small ridge extending over a portion of the back (river dolphins), or entirely non-existant (right whale dolphin).

Most species of dolphins also bear a dorsal fin on their backs, made from the same dermal tissue as the tail flukes, and is believed to act as a stabilizer while moving.  In some species (orca, grampus), the dorsal fin is rather large relative to the size of the body; in several others the fin is a small ridge extending over a portion of the back (river dolphins), or entirely non-existent (right whale dolphin).

Dolphins range in size from Maui's dolphin (''Cephalorhynchus hectori maui'') of [[New Zealand]], which at 3.9 feet in length makes it the smallest cetacean of any kind; to the male [[orca]] or killer whale (''Orcinus orca''), which can reach lengths in excess of 30 feet and weigh in at 6 tons.

Dolphins range in size from Maui's dolphin (''Cephalorhynchus hectori maui'') of [[New Zealand]], which at 3.9 feet in length makes it the smallest cetacean of any kind; to the male [[orca]] or killer whale (''Orcinus orca''), which can reach lengths in excess of 30 feet and weigh in at 6 tons.

The word "porpoise" has also been used as an alternative name for dolphins; indeed, both names have been used interchangably between dolphins and members of Phocaenidae, which include the true porpoises.  The differences between the two are rather slight: dolphins have a beak-shaped snout bearing conical teeth, while porpoises have a blunt snout bearing spade-shaped teeth.

The word "porpoise" has also been used as an alternative name for dolphins; indeed, both names have been used interchangeably between dolphins and members of Phocaenidae, which include the true porpoises.  The differences between the two are rather slight: dolphins have a beak-shaped snout bearing conical teeth, while porpoises have a blunt snout bearing spade-shaped teeth.

"Dolphin" is also a name of a species of game fish related to mackerals, and known as either mahi-mahi or dorado.

"Dolphin" is also a name of a species of game fish related to mackerals, and known as either mahi-mahi or dorado.

==Diet==

==Diet==

Nearly all dolphins feed on small fish (herring, sardines, mackeral, etc.), shrimp, or mullusks (squid, cuttlefish); some individuals have been seen feeding exclusively on one particular food source as a matter of preference.  Orcas are the exception, as they feed not only on fish, but seals, other dolphins, and several species of the larger whales as well.  One female orca off [[California]] has also been spotted routinely killing [[great white shark]]s (''Charcharodon charcharias'') just for their livers.

Nearly all dolphins feed on small fish (herring, sardines, mackerel, etc.), shrimp, or mullusks (squid, cuttlefish); some individuals have been seen feeding exclusively on one particular food source as a matter of preference.  Orcas are the exception, as they feed not only on fish, but seals, other dolphins, and several species of the larger whales as well.  One female orca off [[California]] has also been spotted routinely killing [[great white shark]]s (''Charcharodon charcharias'') just for their livers.

==Intelligence==

==Intelligence==

Dolphins are rated as being superior in intelligence to domestic dogs, and some scientists have made claims that they equal or surpase the intelligence of some primates.  It has also been theorized that the sounds made by dolphins are actually a language.  John Lilly, an American neurologist, conducted some experiments during the 1960's to test the validity of this theory without success; however, research still continues at several universites and laboratories around the world.

Dolphins are rated as being superior in intelligence to domestic dogs, and some scientists have made claims that they equal or surpase the intelligence of some primates.  It has also been theorized that the sounds made by dolphins are actually a language.  John Lilly, an American neurologist, conducted some experiments during the 1960s to test the validity of this theory without success; however, research still continues at several universities and laboratories around the world.

==Dolphins and man==

==Dolphins and man==