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Thursday, April 24, 2003

ANIMAL TRACKER

Bottlenose dolphin


* Japanese name: Bandou iruka
* Scientific name: Tursiops truncatus
* Description: Dolphins are marine mammals, toothed whales, with a broad dorsal fin and a long snout with a characteristic "smile." They grow to between 1.9 and 4 meters long, and weigh 90-650 kg, living for up to 50 years. The dorsal side of the body is dark blue, brown-gray or even silver in color; the underside is white-pink; and the tip of the snout is usually white. Like other whales, they breath through a blow hole. The body tapers into a powerful V-shaped tail, and the tail fins (called flukes) propel the animal through the water at high speeds. The name "Tursiops" comes from the Latin word tursio (porpoise) and the Greek ops (face).
* Where to find them: Bottlenose dolphins can be seen off the coast of all parts of Japan, even north to Hokkaido. They live in groups of 20 to 200. They can also be seen in the open ocean -- and on supermarket shelves across Japan.
* Food: Dolphins are opportunistic foragers: They eat a wide range of animals, including fish, and invertebrates such as shrimp and squid. They eat around 6 kg of seafood a day. They hunt by using sonar, often working in a team to "herd" fish. Pregnant dolphins gestate for 12 months, and young suckle milk for up to 18 months.
* Special features: Dolphins have lost the body hair characteristic of other mammals, and teats and genitals are hidden in the streamlined body. The nasal passage opening in the blow hole is separated from the throat (in us and other mammals, the passage is shared), enabling dolphins to open their mouths underwater without drowning. But the most extraordinary characteristic of dolphins is their intelligence: They have larger brains than humans. They communicate with elaborate whistles and rasps. Scientists have yet to decipher dolphin "language," but the hope is that one day humans will be able to communicate with them. Dolphin whistles are thought to be "signatures": nametags for individual dolphins. Newborn dolphins quickly develop their own unique signature whistles. Adults can mimic the signature whistles of other dolphins: This might mean that they can call dolphins by name.



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