Tursiops truncatus
bottlenosed dolphin

Tursiops truncatus is found in warm temperate and tropical oceans and seas worldwide. In waters of the United States, bottlenose dolphins range as far north as New Jersey in the summer and in the west to Point Conception, California. Year-round they can be found off the coasts of Hawaii and Florida. They occur as far south as Panama in both the Atlantic and Pacific oceans. There are also populations that occur in the Gulf of Mexico, the Caribbean Islands, the Mediterranean Sea, and the Indian Ocean.

Bottlenosed dolphins prefer warm, shallow inshore waters. They are commonly seen in bays and lagoons, and sometimes ascend large rivers. In certain areas they range as far offshore as the edge of the continental shelf.

Bottlenosed dolphins are the largest of the beaked dolphins. Head and body length is 175-400 cm, with males being much larger than females. Pectoral fin length is 30-50 cm, and dorsal fin height is approximately 23 cm. Width of the tail flukes is about 60 cm. Newborn calves are 98-126 cm long and weigh 9 to 11 kg. The genus Tursiops is distinguished by the short, well-defnined snout or beak which is about 8 cm long. There are 20 to 28 sharp conical teeth on each side of each jaw, with each tooth about 1 cm in diameter. Tursiops truncatus also has a larger brain than those of humans, and shows a high degree of intelligence.

Tursiops truncatus is a distinctly social species, usually traveling in groups of as many as a dozen, but they have been seen in aggregations of several hundred. Most populations do not migrate, but travel widely to find food or locate waters of preferred temperature. They swim at speeds of approximately 12 miles per hour.

Tursiops truncatus displays a wide variety of vocalizations and is hypothesized to have a complex language that people may eventually be able to use to communicate meaningfully with dolphins. Each dolphin appears to have its own distinctive whistle by which it communicates a limited amount of information on its identity, location, and condition to other dolphins. Dolphins also use clicklike pulses produced by nasal sacs in the forehead for echolocation.

From the time of the early Greeks, it has often been claimed that dolphins will save humans from drowning or from shark attacks, although concrete evidence for these claims have not been found. Dolphins will support members of their own kind at the surface of the water however, to permit them to breathe when they are in distress.

In the wild, Tursiops truncatus feeds on squid, shrimp, eels, and a wide variety of fishes. In some waters, bottlenoses habitually follow shrimp boats to consume what the shrimpers discard or miss. They often hunt as a team, herding small fishes such as menhaden ahead of them and picking off the stragglers. They have been observed to chase fish onto mudflats, then slide out of the water to seize their prey. They generally consume approximately 6-7 kg of seafood per day.

Fisherman sometimes shoot bottlenosed dolphins because they believe the dolphins are competing with them for fish and other desirable catch.

Bottlenosed dolphins have been used since 1949 in shows in oceanariums that feature dolphins doing tricks to entertain the audience. They are easily trained to perform acrobatics, locate hidden objects and play with balls. They are also used widely in research work involving cetacean physiology, psychology and sociology. Dolphins have been hunted by people in many parts of the world for meat and products (such as fertilizer, body oil for cooking and illumination, and jaw oil used as a lubricant in fine machinery) made from dolphin parts.

Protected under the Marine Mammal act of 1972, taking of dolphins is only allowed with a special permit. Because of commercial fishing operations dating back to the late 1800's, bottlenosed dolphin numbers were drastically reduced by the turn of the century. The U.S. National Marine Fisheries Service estimated that there were 3,000 to 10,000 bottlenosed dolphins off the east coast of the United States in 1981. The biggest threat now to dolphin populations is probably commercial fishing for tuna. Dolphins school with tuna and sometimes become trapped in nets set by fishing fleets.