The scientific name of mermaid

Chinese name: Dugong

Chinese aliases: manatee, "seahorse", mermaid, mermaid, South China Sea cow.

Latin scientific name: dugong

Name: Muller, 1776.

English name: Dugong

Classification:

Portal: Chordata (Chordata)

Class: mammals

Objective: SIRENIA.

Family: Dugong Family.

Genus: Dugong

Appearance characteristics

It is the only herbivorous mammal in the ocean. The biggest difference between it and other manatees is that the tail of manatees is round, while the tail of dugong is similar to that of dolphins. Dugong's head is very big, and the ratio of head to body is the largest among marine animals. The mouth is huge and vertical, and the tongue is big, so it is easier to eat marine benthos and exclude sand. Dugong's stomata are on the top of the head, and it takes air every 15 minutes on average. The skin on the head and back is hard and thick.

Dugong is large and spindle-shaped, with a body length of about 2.4 to 2.7 meters. Individuals over 3 meters are quite rare. Generally speaking, women are a little older than men. Smooth skin, brown to dark gray appearance, lighter abdomen color than back, and sparse hair on body surface. The neck is short, but you can still turn your head or nod in a limited way. The forelimbs are short, fin-shaped, with slightly rounded ends and no toenails; The pectoral fin is the main source of propulsion for young dugong, and it turns into caudal fin in adulthood. There are 1 pairs of breasts, and nipples are located at the base of forelimbs. Dugong has no outer ear shell, only small ear holes and small eyes. The nostrils are located at the top of the snout and are covered with a film when diving. The wide and flat mouth is located below the thick snout, and the short beard of the mouth is an important tool for eating.

There are two pairs of incisors, three pairs of premolars and three pairs of molars in the upper and lower jaws of dugong, but all the teeth do not exist at the same time. As they get older, they will lose the first 1 pair of incisors, all premolars and the first 1 pair of molars, and the remaining two pairs of molars will grow for life. The second pair of male front teeth will penetrate the upper jaw at the age of 12- 15, but will be covered by a thick upper lip when opening the mouth. Women rarely see exposed front teeth, but a few will stay until they are around 30 years old.

Dugong's lungs are very large, extending from the chest to the kidneys and separated from other organs by a horizontal diaphragm. Bronchus penetrates into most areas of the lung, with few branches, and most of them are composed of cartilage. It is not clear whether dugong's lungs will collapse like whales when diving. Compared with other marine mammals, their fat layer is thinner, and there seems to be no heat countercurrent exchange system around their bodies (a vascular structure in which arteries and veins at the ends of limbs are close to each other to maintain body temperature), which may be related to their living in a warm ocean. The structure of the stomach is simple, and the large intestine is very large (twice as heavy as the stomach), which is supposed to be the main digestion place of cellulose, with a length of more than 25 meters, which is equivalent to twice the length of the small intestine.

Basic information:

Length and weight at birth: 1. 15m, 25-35kg.

Maximum length and weight record: 4. 16m, 1.0 16kg.

Life expectancy: 73 years.

distribution range

Dugong is a marine mammal (occasionally entering the freshwater basin), which is mainly distributed in the western Pacific Ocean and the Indian Ocean coast, especially in areas where algae are abundant. Although people think they live in shallow waters, they sometimes migrate to deeper waters, about 23 meters deep. Their distribution range is not continuous, which may be related to habitat suitability and human activities. Dugong in the Indian Ocean starts from the east coast of Africa, passes through the Red Sea, Persian Gulf, South Africa and Madagascar to the Arabian Sea and Sri Lanka, and most of them are small in number. In the Pacific region, including Indonesian, Malaysian, Papua New Guinea and other east indies, Taiwan Province Province and Okinawa in the north, and the adjacent waters outside southern Australia in the south. In some areas, they are called manatees, porcupines or sea camels.

In China, it is mainly distributed in the coastal areas of Guangxi in Beibu Gulf. There are also traces along the southern coast of Guangdong and Taiwan Province Province, as well as along the western coast of Hainan Island, such as Bashuo Port.

living environment

Most of them haunt seaweed about 20 meters away from the coast, sometimes they enter the estuary with the tide, and then return to the sea with the ebb tide after foraging, and rarely swim out to sea. Living in a warm ocean, the seawater temperature is above 20℃. Its distribution is closely related to water temperature, ocean currents and algae as the main food.

Living habits

Slow action, mild temperament, poor eyesight, sensitive hearing, and lethargy on weekdays. After a hearty meal, I like to dive to the bottom of the sea 30 to 40 meters deep, wait at rocks and other places, and never go far from the coast to the deep sea. I have certain requirements on sea temperature and don't want to go to Leng Hai. Sensitive to cold, the water temperature is lower than 15℃, and it is easy to get pneumonia and die; Poor water quality is also prone to skin ulcers and internal parasites.

Feeding habits: Dugong only feeds on plants growing at the bottom of the sea, with a depth of about 1 to 5 meters. It feeds on the roots, stems, leaves and some algae of various marine plants, and often eats the whole plant. They don't bite seaweed with their front teeth, but eat with their greedy big kisses. Sometimes they leave traces of eating, which can be seen at low tide. Dugongs usually eat during the day or at night, but in areas where human activities are frequent, they mostly eat at night. More than 45 kilograms of aquatic plants are consumed every day, and a large part of the time is spent on food intake. The action of foraging for seaweed is similar to that of cattle. While chewing, I kept swinging my head, so I got another manatee.

They like to move in groups. They move in families with 2-3 heads. Although they often act alone, they will form small groups of about six, sometimes reaching hundreds or more. Living at the bottom of the algae area with good concealment conditions, it regularly rises to the surface to breathe. Shy by nature, as long as you are a little scared, you will run away at once. Never far from the coast. The speed of action is not fast, generally about 2 nautical miles per hour, only 5 nautical miles when escaping. Generally, it floats every 1 to 2 minutes, but sometimes it will dive for more than 8 minutes. When floating, only the tip of the snout comes out of the water, and when diving, the whole body will rotate vertically like a dolphin 1 circle. Generally speaking, I swim about 25 kilometers every day.

The call is a continuous rolling sound or a higher shrill sound, similar to a manatee. As we all know, sharks, killer whales and crocodiles occasionally prey on dugong.

Growth and reproduction

The reproductive behavior of dugong is similar to that of other manatees. Usually, 1 estrous females attract many males, and they will fight each other for mating rights. The mating process has been witnessed several times. The first is the "following period", in which a group of male dugongs will swim to the female, and the female will try to escape from them. Then there is intense activity, and the male will flap, splash and keep spinning with his tail fin; Then mating begins. At this time, the male will hug the female from below, and other males will push each other and hug the female at the same time.

Reproductive behavior takes place during most of the year. The gestation period is about 1 1 to 14 months. Having a baby every three years takes about seven to eight years from birth to maturity. Young dugong is fragile and thin-skinned, and often dies in the mouth of sharks. Young dugong begins to eat solid food at about 3 months, but will not be weaned until 18 months, while female dugong eats several times as much during lactation. After that, the young dugong will stay with his mother for several years. Dugong can be produced all year round, but there seems to be a seasonal peak. Birth intervals range from two and a half to seven years. The average life expectancy of dugong is 78 years.

Dugong in lactation will swim in shallow water with their young dugong. At this point, the nipples of the adult dugong are swollen. Ancient sailors were called "mermaids" when they saw it in poor light and mistook it for a woman.

Demographic situation

Like manatees, the main reason for the decline of dugong population is the interference of human activities. According to the bones of dugong found in archaeological sites in UAE, dugong has been hunted for at least 4000 years. Dugong has commercial value all over its body. Excluding edible meat, 1 Only adult dugong can squeeze out 24 to 56 liters of oil, and their skins can be made into leather. Their dense bones are used instead of ivory for carving. Continued hunting has drastically reduced the ethnic groups in some areas. For example, during the 65,438+07 to 65,438+09 centuries, ethnic groups in Madagascar were massacred in large numbers for their meat. Today, they are still hunted in most habitats and sometimes sold in the market. In Australia, dugong has been listed as a protected animal, and only some areas have been hunted by indigenous hunters. In addition, dugongs often die from trawling, shark nets that protect swimmers by the sea, turtle nets and fried fish. They are also victims of crude oil pollution. 1983 The tanker Nowrus capsized in the Persian Gulf, and the crude oil pollution during the Persian Gulf War significantly increased its mortality. Known natural threats include storms, parasites and predation by sharks and killer whales.

Australia is probably the region with the largest ethnic group at present, with an estimated population of about 85,000, of which more than 24,000 dugongs live in the Torres Strait between Papua New Guinea and Australia. The other largest area is in the Persian Gulf, with an estimated number of about 7,000.

The Australian government demolished several docks and explicitly prohibited pollutants from entering the sea directly. Dugong should be released immediately after being caught. However, the situation of dugong is still not optimistic, and the decrease of population may lead to the extinction of the whole population due to inbreeding.

The number of China is unknown. Dugongs are distributed in a narrow area and few in number in China. According to fishermen, the number has been decreasing in recent years, and the sea areas that used to be common in Guangxi and other places are now rare. Before 1950s, fishermen regarded dugong as a "strange fish" and never caught it. 1958, they started hunting. During the period of 1958- 1962, 150 heads were caught by incomplete statistics, and 40-50 heads were caught from 1970 to the middle period, which became less and less. Dugong is big and tender, and the first cervical vertebra and teeth can be used as decorations, so it will be killed if it is stranded or accidentally caught. There are not many dugong resources in Beibu Gulf. From 1950s to 1960s, fishermen from Hepu, Guangxi and Hainan were rounded up in coastal areas, and dozens of them were captured every year. In the 1980s, there were still indiscriminate bombing and overfishing, which seriously damaged the resources.

1992, China established Guangxi Hepu Dugong National Nature Reserve with an area of 350 square kilometers. The water quality in this area is good, there are many tidal ridges, tidal troughs and shoals in the intertidal zone under water, and the algae are lush and the habitat is suitable. It is a region with dense Confucianism and good activities in China. In recent years, shatian town residents in Hepu have seen dugong.

Protect value

The name of dugong is directly transliterated from Malay, and some people call it "Nanhai Niu". It shared a common ancestor with Asian elephants on land, and later entered the ocean, still maintaining the habit of eating grass. It has a history of 25 million years. It is a rare marine mammal and one of 43 endangered vertebrates in China. It has important reference value for studying biological evolution and animal classification. Pan, a famous biologist and professor of Peking University, called Rugen "the flagship animal of wetland biodiversity protection". He said: "The protection of dugong will definitely affect the survival and protection of other creatures in the whole ecosystem, and will definitely affect our protection of the whole wetland ecosystem."

Protection level

Protection level: national first-class protected animals.

Red Book Endangered Level: Endangered (E)

IUCN rating: vulnerable

Endangered Species Convention: Appendix I

If you think this entry needs improvement, adding new content or modifying wrong content, please edit it.

Open classification:

Biology, manatee, animal, dugong, dugong.