(Neophocaena phocaeniodes)

Morphology

The Finless Porpoise is one of the smallest members of the family Phocoenidae and resembles a small Beluga whale.  The length of their routund body ranges from 1.4 to 1.65 meters, while their weight is typically between 30 to 45 kilograms. The small head of this species has no beak, but it unique from other members of this family, as it is the only porpoise to possess a rounded melon. The mouth is small, and the mouthline curves upward toward the eyes.

Color

This porpoise is a pale blue-grey color dorsally. The ventral portion, especially between the flippers, is much lighter. The lips and chin are also lighter in color, with the exception of a dark "chin strap" which surrounds the dorsal portion of the mouth. This species is sometimes referred to as the "Black Porpoise" because the body quickly turns black after death. While alive, however, the color remains light, only darkening slightly with age.

Fins

The most significant characteristic of this species for identification is the lack of a dorsal fin, hence the name Finless Porpoise. There is, however, a ridge that runs along the back from the flippers to the tail stock. This ridge is covered with tubercles. The flippers in this species are long with a blunt tip. The fluke, which is rarely raised above the surface of the water when diving, has a notch, pointed tips, and a concave trailing edge.

Behavior

Most Finless Porpoises are timid and hard to approach. However, the Yangtze River population exhibits behavioral characteristics distinct from other populations of this porpoise, as they do not appear to be as shy. This population, probably accustumed to the heavy traffic of the river, do not appear to be easily frightened of boats or people.

Although this species is not considered gregarious, they are sometimes observed in groups of 5 to 10 individuals. Pods of 50 members have also been observed, probably gathered to take advantage of rich feeding grounds.

Swimming Style

Although they show no acrobatics in the water, Finless Porpoises are believed to be very active swimmers. They typically swim just beneath the surface of the water and roll to one side when surfacing to breath. This rolling movement disturbs very little water on the surface, so they are often overlooked when rising to breath. Surfacing generally lasts for one minute, as they take 3 to 4 quick successive breaths, then quickly disappear into the water. When they reemerge, the Finless Porpoise is often located a great distance from the point where they dove beneath the water's surface.

Life History

Differences in reproductive biology exists between the various populations of Finless Porpoises. For example, calving season for the Japanese population is believed to occur in October, while calving season for the Yangtze River population takes place from February to April. Calves ride on the backs of their mothers, gripping the dorsal ridge running from the flippers to the tail stock. When the mother surfaces to breath, the calf comes entirely out of the water.

Diet

Although Finless Porpoises do eat squid, shrimp, and small fishes, this species is unique from other members of the family Phocoenidae in thier diet as well. This porpoise has an adapted diet to suit thier environment of estuaries, mangroves, and rivers, as they eat rice, grain, and eggs deposited on vegetation.

Distribution/Population

This porpoise is generally found in the coastal waters of the Indo-Pacific from Pakistan to China. As a typically inshore species, the Finless Porpoise is rarely sighted further than 5 kilometers from the coast. This porpoise survives well in murky turbid waters. It is found in both saltwater and freshwater, in warm rivers, mangroves, estuaries, deltas, and salt marshes. Specifically, this species is present in the Yangtze River in China.

Harms

Since this species is the most coastal of all porpoises, it has the most interaction with humans. This interaction often puts the Finless Porpoise at risk. Like other porpoises, large members of this species are killed by entanglement in gill nets. Also, this porposie is widely hunted in Japan by guns and "fishforks". In addition, unlike other members of this family, Finless Porpoises have been captured and placed on live display in Japan for over 15 years.