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Finless Porpoise

(Neophocaena phocaenoides)

The finless porpoise lives in coastal waters of Asia, from the western side of the Persian Gulf to about 38°N Japan in the east, although some of the range may not be confirmed before local populations are destroyed by human impacts. They prefer waters with soft or sandy bottoms less than 50 m deep, and in some areas they range up estuaries, rivers, and shallow channels. Besides subtle population variations, where some are light gray at birth and darken with age, and others just the reverse, there may be genetically separate tropical and temperate zone species. (Photo courtesy of the Institute of Hydrobiology, Chinese Academy of Sciences)
NpWangDingUW02
The Yangtze finless porpoise is a smaller, fresh water population now reduced to about 2000 and found only in the Yangtze River and several large lakes of China. The Chinese government is struggling hard to save this species from the same human threats that endanger the Baiji. The porpoises' preferred habitat makes them vulnerable to fishing and pollution throughout their range. Some marine-form finless porpoises near Hong Kong and Japan have had dangerous levels of contaminants in their bodies, which have been found to suppress immune systems in other species. (Photo courtesy of the Institute of Hydrobiology, Chinese Academy of Sciences)
NpWangDingMouth01
This is how the finless porpoise turns quickly, curling into his belly. Belugas turn like this also, because both species are slow swimmers and don't have dorsal fins. The only known sounds from the finless porpoise are high frequency echolocation clicks, but perhaps those also serve as simple communications. Rarely are more than four found together, so we assume they have a limited social structure. Short dives of perhaps 20 seconds are usually all the porpoises need to catch prey, such as small fish, squid, shrimp, and octopus, although they can stay submerged for several minutes. While some temperate zone populations seem to migrate seasonally, in the tropics they seem to stay in preferred areas year-round. Females are 1.55 meters long, and males grow to 2 meters. A mother may have a calf every other year, after an 11-month gestation period. Calves are weaned after about seven months, and the maximum age recorded is at least 33 years old. (Photo courtesy of the Institute of Hydrobiology, Chinese Academy of Sciences)
NpWangDingCurve01
These two finless porpoises move together like airplanes in formation, and indeed as they swim submerged it seems much like flying. See the small bumps called denticles or tubercles along a ridge on their backs? No one knows what the bumps are for. And notice how far the upper porpoise has turned his head to look at the camera? The beluga whale can do this, but few other cetaceans can, because their neck vertebrae are locked together. Even though the finless porpoise and beluga may look alike at times, they are very different creatures. (Photo courtesy of the Institute of Hydrobiology, Chinese Academy of Sciences)
NpWangDingPairUW03

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