dugong(lat. Dugong dugon) - aquatic mammal; the only modern representative of the dugong genus of the dugong family of the siren order. The name "dugong" comes from the Malay duyung, meaning "mermaid", "sea maiden".
The smallest representative of the siren squad: body length 2.5-4 m, weight reaches 600 kg. The maximum recorded body length (a male caught in the Red Sea) was 5.8 m. Sexual dimorphism is pronounced: males are larger than females.
Range of dugongs quite large and includes the warm coastal waters of the Pacific and Indian Oceans, as well as the Red Sea. The largest population of dugongs lives along the northern coast of Australia between Shark Bay and Moreton Bay, and the second largest is found in the waters of the Persian Gulf.
But the concept of "large population" in relation to dugongs is very relative: for hundreds of years they were hunted for meat, skin, bones and fat, so now this species is seriously threatened, it is listed in the Red Book and is under international protection.
The dugong differs from its closest relatives, the manatees, in its powerful, flat, large, whale-like tail, which gives it the ability to travel long distances. And with flippers - like a steering wheel - the dugong sets the direction of movement. The dugong has no hind limbs, and its brown coat is covered with short, stiff bristles. A thick layer of subcutaneous fat makes his body rounded. The muzzle of a dugong looks lopped off and ends in fleshy lips hanging down. The nasal openings are located on the upper lip, and to make it easier to breathe, the dugong bends it in a special way. Small tusks grow in the mouth - in males they are noticeably larger, and in females they are hidden in the jaws.
The dugong plucks algae from the bottom with its muscular upper lip. If it weren't necessary to come up about every six minutes to take a breath, the dugong would only eat. These animals grow up to 3 m in length and weigh about 500 kg. In favorable conditions, their average life expectancy is 70 years. Most of this time they spend alone or with a partner - although sometimes, in large populations, they may gather in flocks.
These animals reach sexual maturity between ten and seventeen years of age. Females give birth to offspring once every three years. The baby develops in the womb for 12 months, and as soon as it is born, the mother pushes it to the surface so that it takes its first breath. Females feed offspring with breast milk for 18-24 months.
These slow, quiet animals are easy prey for many predators. But fortunately the dugong, its imposing figure scares away most of them. Only killer whales, the largest sharks and crocodiles can pose a threat to the dugong.
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Reprinting of articles and photos is allowed only with a hyperlink to the site:The name "dugong" comes from the Malay duyung, meaning "sea maiden" (" mermaid").
Appearance
Body length 2.5-4 m, weight reaches 600 kg. The maximum recorded body length (a male caught in the Red Sea) was 5.8 m. Sexual dimorphism is pronounced: males are larger than females.
A small, inactive head passes into a massive spindle-shaped body, which ends in a tail fin located horizontally. The tail differs in shape from the tail of manatees and resembles the tail of cetaceans: its two lobes are separated by a deep notch. The forelimbs turned into flexible flipper-like fins 35-45 cm long. From the lower limbs, only rudimentary pelvic bones remained, hidden in the musculature. The skin is rough, up to 2-2.5 cm thick, covered with sparse single hairs. The color darkens with age, becoming dull lead or brownish; the belly is lighter.
The head is small, rounded, on a short neck. There are no auricles. The eyes are small, deep set. The nostrils are shifted upward more than other sirens; equipped with valves that close under water. The muzzle looks chopped off; ends with fleshy lips hanging down. The upper lip bears stiff vibrissae bristles and is bifurcated in the middle (stronger in young specimens); its structure helps the dugong to pluck algae. The lower lip and the distal part of the palate are covered with keratinized areas. Young dugongs have about 26 teeth: 2 incisors and 4-7 pairs of molars in the upper and lower jaws. Adults retain 5-6 pairs of molars. In addition, in males, the upper incisors turn into tusks protruding from the gums by 6-7 cm. In females, the upper incisors are small, sometimes they do not erupt. The molars are cylindrical in shape, devoid of enamel and roots.
Lifestyle
Dugongs live in warm coastal waters, shallow bays and lagoons. Sometimes they go out to sea; enter the mouths and estuaries of rivers. They keep above depths of no more than 10-20 m. Most of the activity is feeding, associated with the alternation of tides, and not with daylight hours. To feed, dugongs swim in shallow water, to coral reefs and shallows, to a depth of 1-5 m. The basis of their diet is aquatic plants from the pondweed and water-colored families, as well as seaweed. Small crabs have also been found in their stomachs. When feeding, 98% of the time is spent under water, where they "graze" for 1-3, maximum 10-15 minutes, then rise to the surface for inspiration. They often “walk” along the bottom on their front fins. Vegetation is torn off with the help of a muscular upper lip. Before eating a plant, the dugong usually rinses it in water, shaking its head from side to side. A dugong consumes up to 40 kg of vegetation per day.
They keep alone, but over feeding places they gather in groups of 3-6 goals. In the past, herds of dugongs up to several hundred heads were noted. They live mostly settled; some populations make diurnal and seasonal movements, depending on fluctuations in water levels, water temperature and food availability, as well as anthropogenic pressure. According to the latest data, the length of migrations, if necessary, is hundreds and thousands of kilometers. The usual swimming speed is up to 10 km / h, but a frightened dugong can reach speeds of up to 18 km / h. Young dugongs swim mainly with the help of their pectoral fins, while adults swim with their tails.
Dugongs are usually silent. Only excited and frightened, they emit a sharp whistle. The cubs make bleating cries. The sight of dugongs is poorly developed, hearing is good. Captivity is far worse than manatees.
reproduction
Breeding continues throughout the year, varying in peak times in different parts of its range. Male dugongs fight over females using their tusks. Pregnancy is believed to last a year. There is 1 cub in the litter, rarely 2. Births take place in shallow water; a newborn with a body length of 1-1.2 m weighs 20-35 kg, is quite mobile. During diving, the cubs cling to the mother's back; milk is sucked upside down. Grown up cubs gather in flocks in shallow water during the day. Males do not take part in the upbringing of offspring.
Milk feeding continues up to 12-18 months, although at 3 months young dugongs begin to eat grass. Sexual maturity occurs at 9-10 years, possibly later. Large sharks prey on young dugongs; adults can only be a threat
The most sacred animal in India is the cow. And in the depths of the Indian Ocean lives a mysterious marine inhabitant - the dugong.
The dugong is an aquatic mammal of the siren family that lives in the Red Sea and the Indian Ocean, as well as in the northern waters of Australia. This is a rather large and unusual animal.
The name "dugong" in translation from the Malay language means "sea maiden", "mermaid". In the old days, myths about sirens and mermaids were created in the image of the dugong.
First of all, let's try to clarify who the sirens are. Sirens are a class of herbivorous mammals, which includes only four representatives. They live in water, the main food is sea grass and algae. Since dugongs "graze" in shallow waters in secluded coastal waters, they are often called sea cows.
Mammals have a massive cylindrical body, thick skin, with many folds, which outwardly very much resemble seals. However, dugongs, unlike seals, cannot move on land. In the process of evolution, their paws were completely transformed into fins. It also lacks hind limbs and dorsal fins.
Of all the representatives of the sirens, dugongs are the smallest. The body length is no more than 4 meters, and the weight is about 600 kg. Females usually grow much smaller than males.
The first remains of dugongs are dated at 20 million years old. In those distant times, these animals were able to move quietly on land, as they had all four limbs. But even then they spent more time in the water. And after a certain period of time, they completely lost the opportunity to get out to the surface of the earth. The reason for this was their great weight, since weak fins simply cannot physically support about 500 kg of the weight of a mammal.
And dugongs also swim not very fast and skillfully. Basically, they carefully move along the bottom, pushing off with their front fins. On the "sea fields" they not only eat grass and algae, but also lift sand and bottom soil with their muzzle in search of juicy roots. Nature endowed sea cows with a callused mouth and tongue to make it easier for them to chew treats. In adult dugongs, the upper teeth transform into small tusks (about 7 cm long). With the help of tusks, it is easier for them to uproot grass, while they leave characteristic grooves on the bottom. It is on such tracks that it is very easy to calculate the places where sea cows graze.
The habitat of sirens depends on the presence of algae and grass, which they eat. When there is not enough grass, then small benthic vertebrates become a delicacy. This change in food preferences is due to the catastrophic decline in aquatic vegetation in some dugong habitats. And without such "extra" food, sea cows would not be able to survive in some areas of the Indian Ocean.
To date, the population of these wonderful animals has declined sharply. In Japan, the number of dugongs is only about 50 heads. And Approximately 7,500 individuals live in the Persian Gulf, although this is rather arbitrary data. A small number of dugongs remain in the Indian Ocean, the Red Sea, the Arabian Sea, the Philippines and the Strait of Johor.
Even in ancient times, people hunted sirens. In the Neolithic era, primitive people left cave paintings of dugongs on the walls. The main purpose of the hunt then was the fat and meat of animals, so it tasted very similar to the "earthly" veal. And the bones of marine mammals were used as material for various crafts and figurines.
Dugongs are peaceful animals. And this was often used by hunters for their valuable skin and fat, as well as meat. Moreover, poaching has reached such proportions that now the dugong population needs legal protection. Otherwise, this species is threatened with extinction, such a fate befell the larger sea cow Steller (they were completely exterminated in just a few decades).
Unpunished dugong hunting, as well as global environmental problems, have led to the almost complete extinction of sea cows around the world. To date, dugongs are listed in the International Red Book with the status of "vulnerable species". The strictest ban is imposed on catching animals with nets, and only aboriginal peoples are allowed to catch animals.
Appearance
The smallest representative of the siren squad: body length 2.5-4 m, weight reaches 600 kg. The maximum recorded body length (a male caught in the Red Sea) was 5.8 m. Sexual dimorphism is pronounced: males are larger than females.
A small, inactive head passes into a massive spindle-shaped body, which ends in a tail fin located horizontally. The tail differs in shape from the tail of manatees and resembles the tail of cetaceans: its two lobes are separated by a deep notch. The forelimbs turned into flexible flipper-like fins 35-45 cm long. From the lower limbs, only rudimentary pelvic bones remained, hidden in the musculature. The skin is rough, up to 2-2.5 cm thick, covered with sparse single hairs. The color darkens with age, becoming dull lead or brownish; the belly is lighter.
The head is small, rounded, on a short neck. There are no auricles. The eyes are small, deep set. The nostrils are shifted upward more than other sirens; equipped with valves that close under water. The muzzle looks chopped off; ends with fleshy lips hanging down. The upper lip bears stiff vibrissae bristles and is bifurcated in the middle (stronger in young specimens); its structure helps the dugong to pluck algae. The lower lip and the distal part of the palate are covered with keratinized areas. Young dugongs have about 26 teeth: 2 incisors and 4-7 pairs of molars in the upper and lower jaws. Adults retain 5-6 pairs of molars. In addition, in males, the upper incisors turn into tusks protruding from the gums by 6-7 cm. In females, the upper incisors are small, sometimes they do not erupt. The molars are cylindrical in shape, devoid of enamel and roots.
Lifestyle
Dugongs live in warm coastal waters, shallow bays and lagoons. Sometimes they go out to sea; enter the mouths and estuaries of rivers. They keep above depths of no more than 10-20 m. Most of the activity is feeding, associated with the alternation of tides, and not with daylight hours. To feed, dugongs swim in shallow water, to coral reefs and shallows, to a depth of 1-5 m. The basis of their diet is aquatic plants from the families of pondweed and water-colored, as well as seaweed. Small crabs have also been found in their stomachs. When feeding, 98% of the time is spent under water, where they "graze" for 1-3, maximum 10-15 minutes, then rise to the surface for inspiration. They often “walk” along the bottom on their front fins. Vegetation is torn off with the help of a muscular upper lip. Before eating a plant, the dugong usually rinses it in water, shaking its head from side to side. A dugong consumes up to 40 kg of vegetation per day.
They keep alone, but over feeding places they gather in groups of 3-6 goals. In the past, herds of dugongs up to several hundred heads were noted. They live mostly settled; some populations make diurnal and seasonal movements, depending on fluctuations in water levels, water temperature and food availability, as well as anthropogenic pressure. According to the latest data, the length of migrations, if necessary, is hundreds and thousands of kilometers. The usual swimming speed is up to 10 km / h, but a frightened dugong can reach speeds of up to 18 km / h. Young dugongs swim mainly with the help of their pectoral fins, while adults swim with their tails.
Dugongs are usually silent. Only excited and frightened, they emit a sharp whistle. The cubs make bleating cries. The sight of dugongs is poorly developed, hearing is good. Captivity is far worse than manatees.
reproduction
A female dugong with a baby
Breeding continues throughout the year, varying in peak times in different parts of its range. Male dugongs fight over females using their tusks. Pregnancy is believed to last a year. There is 1 cub in the litter, rarely 2. Births take place in shallow water; a newborn with a body length of 1-1.2 m weighs 20-35 kg, is quite mobile. During diving, the cubs cling to the mother's back; milk is sucked upside down. Grown up cubs gather in flocks in shallow water during the day. Males do not take part in the upbringing of offspring.
Milk feeding continues up to 12-18 months, although at 3 months young dugongs begin to eat grass. Sexual maturity occurs at 9-10 years, possibly later. Young dugongs are preyed upon by large sharks. Life expectancy - up to 70 years.
population status
Dugongs are hunted for meat that tastes like veal, as well as for fat, skins and bones, which are used for ivory crafts. In some Asian cultures, dugong body parts are used in traditional medicine. From an animal weighing 200-300 kg, 24-56 liters of fat are obtained. Due to predatory prey and habitat degradation, the dugong has become rare or extinct in much of its range. Thus, according to estimates based on the frequency of catching dugongs with nets, its abundance in the most prosperous part of its range, off the coast of Queensland, decreased from 72,000 to 4,220 heads from 19 to 2012.
Currently, fishing for dugongs with nets is prohibited and they are harvested with harpoons from boats. Mining is allowed as a traditional trade of aboriginal peoples. The dugong is listed in the Red Book of the International Union for Conservation of Nature with the status of "vulnerable species" ( Vulnerable).
Dugong in literature
In Jules Verne's novel The Mysterious Island, a dugong is mentioned - the faithful dog of the colonists Top fought with him in the lake named after Ulysses Grant - Grant Lake. In another novel by Verne, 20,000 Leagues Under the Sea, the dugong is hunted by one of the main characters, the harpooner Ned Land.
see also
Notes
Links
- Marsh et al. 2002. Dugong: status reports and action plans for countries and territories. IUCN
Categories:
- Animals alphabetically
- Vulnerable species
- Siren
- Animals described in 1776
- Mammals of the Indian Ocean
- Mammals of the Pacific
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Synonyms:See what "Dugong" is in other dictionaries:
The mammal is fish-like, from 1.5 sazhens long. up to 2 sazhens, a cross between a seal and a whale. Eats grass. Found in the Indian Ocean and the Red Sea Dictionary of foreign words included in the Russian language. Pavlenkov F., 1907. DUGONG ... ... Dictionary of foreign words of the Russian language
dugong- I, m. dugong m. Malay. Aquatic mammal of the family. Sirens living in the coastal waters of the Indian Ocean. ALS 2. Dugongs are very shy, very wary of people and prefer to be in muddy water. ZS 1992 3 71. Similar ... Historical Dictionary of Gallicisms of the Russian Language
Aquatic mammal of the siren order. The length is usually up to 3 m. It lives off the coast of the East. Africa, South Asia, Moluccas, Philippine and Malay Islands, Nov. Guinea and Australia; enters the mouths of the rivers. Few. In the Red Book of the International Conservation Union ... ... Big Encyclopedic Dictionary
Dugongs are the closest relatives of extinct sea cows and still existing manatees. These are large aquatic mammals that feed on plant foods. In addition, they are the only representatives of the dugong family that have survived to our time. That's who, according to some researchers, served as the prototype of the mythical mermaids.
Dugong (lat. Dugong dugon) (eng. Dugong). Photo by Mark Evans
This is what a fantasy one had to have in order to turn this massive animal weighing up to 600 kilograms into a beautiful sea maiden with a fish tail. And this is despite the fact that the average body length of dugongs is 2.5-4 meters. At the same time, they are considered the smallest representatives of the siren detachment. Recall that the length of sea cows reached 10 meters, and their weight could be about 4 tons!
Photo by Geoff Spiby In general, dugongs do not look much different from these giants. They have the same massive spindle-shaped body, at the end of which a large caudal fin flaunts, shaped more like a whale's tail than a manatee's. If in the latter it looks more like a large rounded tennis racket, then in dugongs it is divided in the middle by a deep recess.
The fins are not very long, so adult animals use the tail for swimming, but juveniles use the front fins. Although during feeding, both of them move in shallow water with the help of fins, leaning against the bottom.
The whole body is protected by thick and rough skin, covered with sparse bristles. Color silver grey. It darkens with age and may turn brown. The belly is much lighter.
Photo by Andrey Nekrasov Dugongs have a very small head, as well as their eyes. The powerful muzzle ends with large thick lips, the upper of which is bifurcated in the middle. It is necessary for nutrition. The more mobile these two halves, the easier it is to pick algae from stones and the bottom.
Photo by Camille Menard Like all aquatic mammals, dugongs breathe atmospheric air. To do this, they float to the surface every 10-15 minutes. Special valves in the nostrils help prevent water from getting inside, which close tightly every time the animal goes under water again.
Photo by G. Ryan 99% of their diet consists of algae and aquatic plants of the aquatic and pondweed families. The remaining 2% are those unfortunate crustaceans that do not have time to get out of the vegetation and fall into the mouth with them. Dugongs feed at a depth of 1-5 meters. They move along the bottom with the help of the front fins. Each session of food absorption takes from 3 to 15 minutes, after which the dugongs will definitely emerge for a fresh breath of air and return to the meal again. These are very greedy animals. They can eat up to 40 kilograms of plant food per day.
Photo by Julien Willem The entire contents of the mouth are ground with the help of molars. They are cylindrical in shape, but not enameled and devoid of roots. Therefore, they are easily grinded. Males have small tusks - modified upper incisors protruding from under the upper lip by 6-7 centimeters.
If earlier these animals were distributed over very vast territories, now the total length of their habitat is only about 140 thousand kilometers of coastline. These are the coastal waters of the eastern part of Africa, the western part of about. Madagascar and India, the coast of Southeast Asia, New Guinea, northern Australia, in particular the area of the Great Barrier Reef and the Torres Strait.
They live near the coast. They rarely swim in open waters. Although not so long ago, Queensland marine researchers found that dugongs are able to swim very far and cover distances of several hundred kilometers. The main reasons that push these animals to take such risky actions are small food supplies, violation of the regime of their natural habitat, or active human activity in the sea.
These animals stay alone or in small flocks of 3-6 individuals. They make daily and seasonal movements, depending on various factors: water level and temperature, food availability, and so on. They swim slowly, about 10 km / h, but in cases of alarm they can accelerate up to 18 km / h. Dugongs are silent animals, although their hearing is much better developed than their eyesight. If they make sounds, then these are either sharp whistles warning of danger, or childish bleating sounds.
The female gives birth to only one cub. Births take place in shallow water. In length, the newborn reaches 1-1.2 meters, and weighs 20-35 kilograms. The duration of pregnancy is approximately one year. The lactation period lasts about 1-1.5 years. Although from the age of 3 months, the cubs gradually begin to switch to plant foods. Sexual maturity comes late - at the age of 9-10 years. Although, given that their life expectancy can reach 70 years, this is quite a normal indicator.
Photo by Lorry Tan The meat of these animals is quite in demand, especially among local residents, but due to the rapid decline in their numbers, dugongs have been included in the IUCN (International Union for Conservation of Nature) Red List as a vulnerable species. Hunting for them is carried out under strict control and is allowed only for the local population.
