The
Finless Porpoise (
Neophocaena phocaenoides) is one of six
porpoisePorpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
species. In the waters around Japan, at the northern end of its range, it is known as the
sunameri. A freshwater population found in the
Yangtze RiverThe Yangtze River, or Chang Jiang , Tibetan: Bri-chu, is the longest river in China and Asia, and the third-longest in the world, after the Nile in Africa and the Amazon....
in
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
is known locally as the
jiangzhu or "river pig".
The Finless Porpoise lives in the coastal waters of
AsiaAsia is the world's largest and most populous continent, located in the eastern and northern hemispheres. It covers 8.6% of the earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population.Asia is traditionally defined as part of the...
, especially around
IndiaIndia, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal...
,
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
,
IndonesiaThe Republic of Indonesia is a country in Southeast Asia and Oceania. Indonesia comprises 17,508 islands. With an estimated population of around 237 million people, it is the world's fourth most populous country, with the world's largest population of Muslims.Indonesia is a republic, with an...
and
Japanis an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. A unique fresh water population is found in the
Yangtze RiverThe Yangtze River, or Chang Jiang , Tibetan: Bri-chu, is the longest river in China and Asia, and the third-longest in the world, after the Nile in Africa and the Amazon....
.
The
Finless Porpoise (
Neophocaena phocaenoides) is one of six
porpoisePorpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
species. In the waters around Japan, at the northern end of its range, it is known as the
sunameri. A freshwater population found in the
Yangtze RiverThe Yangtze River, or Chang Jiang , Tibetan: Bri-chu, is the longest river in China and Asia, and the third-longest in the world, after the Nile in Africa and the Amazon....
in
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
is known locally as the
jiangzhu or "river pig".
Distribution
The Finless Porpoise lives in the coastal waters of
AsiaAsia is the world's largest and most populous continent, located in the eastern and northern hemispheres. It covers 8.6% of the earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population.Asia is traditionally defined as part of the...
, especially around
IndiaIndia, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal...
,
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
,
IndonesiaThe Republic of Indonesia is a country in Southeast Asia and Oceania. Indonesia comprises 17,508 islands. With an estimated population of around 237 million people, it is the world's fourth most populous country, with the world's largest population of Muslims.Indonesia is a republic, with an...
and
Japanis an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. A unique fresh water population is found in the
Yangtze RiverThe Yangtze River, or Chang Jiang , Tibetan: Bri-chu, is the longest river in China and Asia, and the third-longest in the world, after the Nile in Africa and the Amazon....
. At the western end, their range includes the length of the western coast of India and continues up into the
Persian GulfThe Persian Gulf, in the Southwest Asian region, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula. Historically and commonly known as the Persian Gulf, this body of water is sometimes controversially referred to as the Arabian Gulf by most Arab states or simply The...
. Throughout their range, the porpoises stay in shallow waters (up to 50 m [160 ft]), close to the shore, in waters with soft or sandy seabeds. In exceptional cases they have been encountered as far as 160 kilometres (100 miles) off-shore in the
East ChinaThe East China Sea is a marginal sea east of China. It is a part of the Pacific Ocean and covers an area of 1,249,000 km². In China, the sea is called the East Sea....
and
Yellow SeaThe Yellow Sea is the name given to the northern part of the East China Sea, which is a marginal sea of the Pacific Ocean. It is located between mainland China and the Korean peninsula. Its name comes from the sand particles from Gobi Desert sand storms that turn the surface of the water golden...
s, albeit still in shallow water.
Physical description
The Finless Porpoise almost completely lacks a
dorsal finA dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
. Instead there is a low ridge covered in thick denticulated skin. This demonstrates that the body shape that has evolved to be the optimum for
sharkSharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs....
s,
dolphinDolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly...
s and
porpoisePorpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
s is not the only possible body shape for a marine animal.
Adult Finless Porpoises are a uniform light grey colour. Newborn calves are mostly black with grey around the dorsal ridge area, becoming fully grey after 4–6 months. Adults grow more than 1.55 m (5 ft) in length and up to 30–45 kg (65–100 lb) in weight. Males become sexually mature at around 4–6 years of age, and females at around 6–9 years of age.
Diet
Finless Porpoises are reported to eat fish and shrimp in the Yangtze River, and
fishA fish is any aquatic vertebrate animal that is typically ectothermic , covered with scales, and equipped with two sets of paired fins and several unpaired fins...
,
shrimpShrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
and
squidSquid are marine cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms and two longer tentacles arranged in pairs...
in the Yellow Sea/Bohai area and off
PakistanPakistan , officially the Islamic Republic of Pakistan, is a country located at the crossroads of South Asia, the Middle East, and Central Asia...
. In Japanese waters they are known to eat fish, shrimp, squid, cuttle fish and octopuses. Finless Porpoises are opportunistic feeders utilising various kinds of available food items available in their habitat. Seasonal changes in their diets have not been studied. They also apparently ingest some plant material when living in estuaries, mangroves, and rivers including
leavesLeaves are an Icelandic five-piece alternative rock band who formed in 2001. Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times. They came to prominence in 2002 with their debut album, Breathe, drawing comparisons to groups such as The Verve and Doves...
,
riceRice is the seed of a monocot plant Oryza sativa, of the grass family . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East, South, Southeast Asia, the Middle East, Latin America, and the West Indies...
, and eggs deposited on vegetation.
Schooling
Finless Porpoises are generally found as singles, pairs, or in groups of up to 12, although aggregations of up to about 50 have been reported. Recent data suggests, that the basic unit of a Finless Porpoise pod is a mother/calf pair or two adults, and that schools of three or more individuals are aggregations of these units or of solitary individuals. Social structure seems to be underdeveloped in the species, and the mother/calf pair is probably the only stable
social unitSocial unit is a term used in sociology, anthropology, ethnology, and also in animal behaviour studies, zoology and biology to describe a social entity which is part of and participates in a larger social group or society....
.
Behaviour and reproduction
Like other porpoises, their behaviour tends to be not as energetic and showy as that of dolphins. They do not ride bow waves, and in some areas appear to be shy of boats. In the Yangtze River, Finless Porpoises are known to leap from the water and perform "tail stands". Breeding occurs in late spring and early summer, after a
gestationGestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals duringpregnancy can have one or more gestations at the same time ....
period of 10–11 months. Calves cling to the denticulated area of skin on their mother's back and are carried by her as she swims. Calves are weaned at 6–15 months.
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 breathe. This rolling movement disturbs very little water on the surface, so they are often overlooked when rising to breathe. Surfacing generally lasts for one minute, as they take 3 to 4 quick successive breaths, then quickly submerge into the water. The Finless Porpoise often surfaces a great distance from the point where it dives beneath the water's surface.
Conservation
There are not enough data to place Finless Porpoises on the
endangered speciesAn endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters. Also it could mean that due to deforestation there may be a lack of food and/or water...
list, except in China, where they are endangered. 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. Except for being briefly hunted after
World War IIWorld War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into two opposing military alliances: the Allies and the Axis...
due to the lack of seaworthy fishing boats, Finless Porposes have never been widely hunted in Japan. It is a species protected since 1930 at the area around Awajima Island,
Takeharais a city located in Hiroshima, Japan.As of 2003, the city has an estimated population of 31,223 and a density of 263.93 persons per km². The total area is 118.30 km².The city was founded on November 3, 1958....
and this coverage had since been extended to all Japanese coastal waters. The primary danger to the species is the environmental degradation. In addition, unlike other members of this family, Finless porpoises have lived under captivity for over 15 years.
There are no well established estimates of the animals' abundance. However, a comparison of two surveys, one from the late 1970s and the other from 1999–2000 shows a decline in population and distribution. Scientists believe that this decline has been ongoing for decades and that the current population is just a fraction of its historic levels. A 2006 expedition estimated that fewer than 400 of animals survived in the Yangtze River.
At the end of 2006 it was estimated that there are about 1400 porpoises left living in China, with between 700 and 900 in the Yangtze, with about another 500 in Poyang and Dongting Lakes.
2007 population levels are less than half the 1997 levels, and the population is dropping at a rate of 7.3 per cent per year. Current conservation efforts were undertaken alongside those for the recently functionally extinct
BaijiBaiji may refer to:* The Baiji or Yangtze River Dolphin * Baiji, Iraq, a city of northern Iraq.* "Baiji" is the pinyin Romanization for Baekje....
. In 1990 5 individuals were relocated to the
Tian-e-Zhou Oxbow Nature ReserveThe Tian-e-Zhou Oxbow Nature Reserve is an area of wetland in the Yangtze basin near Shishou city.The nature reserve was an intended sanctuary for the Baiji and is currently holding 28 Finless Porpoises.-External links:...
and now a population of 28 currently habituate the lake.
Sand dredging has become a mainstay of local economic development in the last few years, and it is an important source of revenue in the region that borders Poyang Lake. But at the same time, high-density dredging projects have been the principal cause of the death of the local wildlife population.
Dredging makes the waters of the lake muddier, and the porpoises cannot see as far as they once could, and have to rely on their highly-developed sonar systems to avoid obstacles and look for food. Large ships enter and leave the lake at the rate of two a minute and such a high density of shipping means the porpoises have difficulty hearing their food, and also cannot swim freely from one bank to the other.
In Popular Culture
- Lettuce Midorikawa from the anime and manga series Tokyo Mew Mew
, also known as Mew Mew Power, is a Japanese shōjo manga series written by Reiko Yoshida and illustrated by Mia Ikumi. It was originally serialized in Nakayoshi from September 2000 to February 2003, and later published in seven tankōbon volumes by Kodansha from April 2003 to May 2004...
is infused with the genes of a Finless Porpoise. As a result, she can turn her lower body into a porpoise tail, giving her the appearance of a mermaid.
External links