Black porpoises, Black finless porpoises, Jiangzhu, Shushuk, Limbur, Indo-Pacific finless porpoise
Finless porpoises are named for and distinguished by the absence of a dorsal fin. Instead of this fin, there is a small ridge on their backs that starts just behind their blowhole and extends as far as the tail flukes. Small circular bumps called tubercles cover the ridge. They have unfused neck vertebrae, which enables unrestricted head movement, and they have a small, curving mouth. About half of them have pink eyes. Their streamlined body is blue-gray, though in northern China and Japan adults are light gray.
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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PiscivoresA piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
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AquaticAn aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract ...
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PrecocialPrecocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
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PredatorPredators are animals that kill and eat other organisms, their prey. Predators may actively search for or pursue prey or wait for it, often conceal...
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NatatorialNatatorial animals are those adapted for swimming. Some fish use their pectoral fins as the primary means of locomotion, sometimes termed labriform...
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ViviparousAmong animals, viviparity is the development of the embryo inside the body of the parent. The term 'viviparity' and its adjective form 'viviparous'...
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
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PolygynyPolygyny is a mating system in which one male lives and mates with multiple females but each female only mates with a single male.
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Generally solitaryGenerally solitary animals are those animals that spend their time separately but will gather at foraging areas or sleep in the same location or sh...
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts with
The Finless porpoise inhabits the coasts of eastern and southern Asia from the Arabian Gulf eastwards to Japan and southwards to Java, Indonesia. It inhabits warm temperate and tropical coastal waters, preferring waters above sandy or soft bottoms, such as mangroves, shallow bays and estuaries. It is also found in large rivers.
The Finless porpoise usually forms small schools and is hardly ever seen in groups larger than 4 individuals. Generally it is solitary or in a mother-offspring group. Some of these groups (mainly near Japan) are migratory. They live in the Inland Sea in the spring, and between late summer and mid-winter they migrate to the Pacific coast. Finless porpoises are active animals, swimming just below the water's surface with sudden, darting movements. They disturb the water little when they break the surface, and they usually roll onto their sides as they do so. They have been seen spyhopping, but rarely breaching. Finless porpoises tend to be shy and they avoid boats. Calves are known to ride on their mother's back, gripping onto the dorsal ridge, coming up out of the water as the mother comes up to breathe.
The Finless porpoise's diet can vary depending on the location. However, they generally eat fish, prawn, shrimp, squid and octopus.
Finless porpoises are polygynous, which means that one male mates with multiple females. Breeding takes place from late spring to early summer. Young are born in winter, spring, or summer, depending on their location, after a gestation from ten to eleven months. Finless porpoises give birth to a single calf. Feeding continues from 6 months to more than a year. The mother is usually the caregiver and swims with her calf until it has fully matured. Males gain sexual maturity between four and six years old, and females between six to nine years
The major threat faced by Finless porpoises is entanglement with fishing nets, especially gillnets. Further threats include hunting, human disturbance, live capture for display, habitat degradation, collisions with boats, and noise and chemical pollution.
The total number of the Finless porpoise population is unknown for today but there are estimates available for certain areas: Japanese waters (estimates for 4 subpopulations): 3,807 porpoises in Ariake Sound/Tachibana Bay; 289 porpoises in Omura Bay; 3,743 porpoises in Ise/Mikawa Bay and 3,387 porpoises in Chiba/Sendai Bay. Near Korea there are 21,532 finless porpoises in offshore waters and 5,464 porpoises in inshore waters. In the Yangtze River there are 1,800 porpoises. Numbers of Indo-Pacific finless porpoises in Hong Kong and adjacent waters are estimated to be at least 217 individuals; in the coastal waters of Bangladesh there are 1,382 porpoises. Overall, Finless porpoise numbers are decreasing today and they are classified as Vulnerable (VU) on the list of threatened species.
