The Yangtze finless porpoise (Neophocaena asiaeorientalis) is a species of toothed whale found only in the Yangtze River in China. It is the country's only known freshwater cetacean following the possible extinction of the baiji. The Yangtze finless porpoise faces many of the same threats that caused the baiji dolphin to possibly become extinct. Due to the rapidly declining population of the species, the Chinese Government and conservation charities are working to help save it from extinction.
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DiurnalDiurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
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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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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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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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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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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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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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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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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts withFlippers of the Yangtze finless porpoise are curved with pointed ends and are relative large, about 20% of their total body length. The finless porpoise tends to be stocky in the middle body and slimmer towards the tail. In general they are more slender in shape than most other Phocoenidae. These cetaceans also have unique foreheads, with a very steep forehead and no beak. In addition, they have an unfused neck vertebrae that allows free head movement. They have 15-22 pairs of teeth on the upper and lower jaw. As denoted by the name, these finless porpoises have flat backs and are completely finless. Instead of a dorsal fin, these porpoises have a dorsal ridge or "groove" that is covered in varying rows of tubercles. These tubercles are round in shape and raised. Recent studies have found that tubercles do have biological and mechanical functions that benefit the porpoise; for example, the tubercles are a sensory organ and can also help with movement through the water. The amount of rows of tubercles and dorsal ridge sizes vary depending on the species and location of the porpoise. The Yangtze finless porpoise usually has a high and narrow ridge with only 1-10 rows of tubercles. Body color also varies depending on habitat location and age. Newborn Yangtze finless porpoises tend to be a dark gray or black color that lightens within a few months to a lighter gray.
Yangtze finless porpoises are found in the main body of the Yangtze River and in connecting lakes. They are exclusive to fresh water, making them different from other finless porpoises. They are usually found in shallow bay areas, swamps, and estuaries year-round as they are not a migratory species. However, distribution changes do occur seasonally. In the winter the highest distribution was found in the middle and lower regions of the Yangtze River. Their preferred climate is tropical or warm temperatures.
Yangtze finless porpoises are shy and do not come to the surface of the water often when there is human activity nearby. They are usually most active when eating and usually spend most of their time near river banks or at the merging of two waterways. Yangtze finless porpoises travel in small groups of about 3 to 6 individuals; however, groups of 20 have been reported. A radio-tracking study confirmed that the average diving behavior consisted of one long dive followed by two shorter dives. These longer dives were more common during the daytime. In the Yangtze River, finless porpoises often leap from the water and perform "tail stands". At night they usually go into sleep cycles and are less active. Another unique behavior of these finless porpoises is that mothers have been seen carrying calves on their backs. An additional uncommon aspect is their method of communication. Rather than communicating through whistles, as most dolphin species do, these porpoises use echolocation and ultrasonic pulses.
Yangtze finless porpoises are carnivores (piscivores) and their diet may vary according to the season and the dominant prey of the season. They eat various fish and cephalopods.
Little is known about the mating system of Yangtze finless porpoises. After a gestation period that lasts approximately one year, the female gives birth to a single calf. The calve is usually weaned after 6 months and becomes reproductively mature at around 6 years of age.
Increased traffic, pollution, and habitat degradation of the river are the main threats to Yangtze finless porpoises. The increased vessel traffic may cause death from propeller strikes, and the boat noise may mask the porpoise's ability to communicate with other porpoises, as well as hindering their biosonar which compromises foraging and locomotion. Porpoise mortality associated with vessel collisions has increased substantially in recent years, in contrast to mortality from by-catch. Widespread sand mining of the river and lake beds and banks has destroyed important habitats for porpoises and food items, as well as other environmental issues. This problem is especially serious in the Dongting and Poyang Lakes. Dams also have major effects on river and lake ecology and inhibit access between the river and adjoining lakes or tributaries in the Yangtze, as well as affecting migrating prey items. The Three Gorges Dam in particular has altered and will continue to alter, downstream conditions in the Yangtze River and its connected/adjoining lakes. Construction of the Poyang Lake Dam is likely to damage the remaining population of this species severely. Another reason that Yangtze finless porpoises have been dropping in numbers is because of underwater noise pollution. If spectra levels in the water surpass the underwater acoustic thresholds for the porpoise, their chance of survival is greatly threatened.
According to the IUCN Red List, the total population size of the Yangtze finless porpoise is approximately 1,800 individuals. Currently, this species is classified as Critically Endangered (CR) on the IUCN Red List, and its numbers today are decreasing.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...