There are only four species of dolphins on the planet that are able to live in fresh water and Amazonian dolphin one of them. It is known by many names - Amazonian dolphin, white river dolphin, inia, bowto and Amazonian river dolphin.
photo: Joachim S. Müller
Amazon Dolphin ( Inia geoffrensis) ‒ aquatic mammal suborder of toothed whales. This is a medium-sized dolphin, with males being larger than females. They can weigh around 160 kg and up to 2.5 meters in length. Their characteristic is the absence dorsal fin and more long nose than most other dolphin species.
They are very intelligent animals, as are all kinds of dolphins. When looking at their anatomy, it was found that their brains are 40% larger than those of the average human. Many people find it fascinating that the Amazonian dolphin can move its head 180˚. This is possible because his vertebrae are not fused.
photo: Joachim S. Müller
There is a common misconception that the Amazonian dolphin is a slow swimmer due to its body shape. In fact, it is able to swim faster than most other dolphin species. However, as a rule, it simply does not have such a need. These dolphins swim at a slower pace to conserve energy.
Everyone knows that dolphins are very social animals and the Amazonian dolphin is no exception. They usually do not gather in groups of more than four individuals. However, this does not mean that they do not communicate with each other. Highly important ways communication are considered, chirps, clicks and whistles, as well as many non-verbal signals.
photo: Paulo Neves
They are very tolerant of each other as they are not territorial. The range they use to find food often brings them into contact with each other. Many experts as well as observers are fascinated by the antics of the Amazonian dolphins. They often rise to the surface, where they perform many interesting and exciting tricks: they move on their side, swim on their backs, jump and do spins.
As you may have guessed from their name, these dolphins are natives of the Amazon River. They are also found in the Madeira and Orinoco rivers. Amazonian dolphins live only in fresh water with warm temperatures.
Photo: Gabrielle Sim
They migrate to find more warm water during the cool season. It can also cause mating because it tends to be very popular during migration. Migration also contributes to obtaining a sufficient amount of food.
The Amazonian dolphin feeds mainly on small fish, eating 9-12 kg per day (about 2.5% own weight). Its diet is very diverse, including at least 43 species of fish from 19 families. All food is consumed whole, so it is easy for this dolphin to eat entire schools of fish.
Photo: PRO Harold Moses
Females are ready to breed at about 7 years of age, and males at about 10. Partners seek each other through vibration and through the use of their voice messages. Before mating, they will go through a courtship process. During this period, the couple will spend a lot of time talking and playing.
The gestation period lasts 11 months. After that, the female gives birth to one cub, which has a weight of about 7 kg and a length of 75-80 cm. It can stay next to the mother for up to three years. During this period, the mother prepares him for an independent life.
Since these dolphins live mostly in the Amazon River where there are no sharks or killer whales, they have no real problem with predators. However, they certainly have a few problems with humans.
The Amazonian dolphin is listed as vulnerable on the IUCN Red List.
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Bright pink spots flicker among the trees, glide between the branches, gracefully bend around the trunks, swollen with water. It is the river Amazonian dolphins frolicking in the flooded jungle, they are also bouto (for locals) or inii (Inia geoffrensis). The Amazon, flooding during the rainy season, flooded the jungle in its upper reaches, thus giving the dolphins a chance for a real forest hunt. Why do dolphins, the original inhabitants of the salt sea waters moved to fresh water? Healy Hamilton, a biologist at the California Academy of Sciences, explains that about 15 million years ago, during the Miocene era, sea levels were higher, and therefore large parts of the current South America were under the salt water. Hamilton's hypothesis is that over time, the sea gradually retreated to modern boundaries, and part of the dolphins remained in their former territories. And over millions of years in the Amazon, they have become completely amazing creatures, not much like everyone's favorite, movie hero Flipper.
Pink color is not the only way to attract a female. Sometimes a bowto takes a bunch of plants or a piece of wood in its beak, starts spinning and hitting its prey on the water. The locals thought for a long time that this was just a game, until Martin discovered that only males hold objects in their mouths - and only in the presence of females.Bowto reaches almost two and a half meters in length and weighs about 200 kilograms. His distinguishing feature- a long, leathery snout, similar to a beak or a sting, which is so convenient for digging crustaceans from bottom silt and catching fish rushing about in a tangle of branches. The neck vertebrae of Amazonian dolphins do not fuse together, and therefore their heads can turn at an angle of 90 degrees to the body - a most useful ability for navigating through trees. Another distinctive feature river dolphins- small eyes muddy water vision is still of little use, and it is easier to search for prey using echolocation. River dolphins are not only found in the Amazon, they can also be found in the Indian Ganges, in the Pakistani Indus and in the waters of the Rio de la Plata between Argentina and Uruguay. There are four species of river dolphins in total, and the bowto is the largest of them. Until recently, there were five species of river dolphins. However, already at the beginning of our century, dolphins from the Chinese Yangtze River were completely destroyed - since 2002, scientists have not been able to detect them. According to Hamilton, at first glance, everything freshwater dolphins appear to be the same, but their four genera belong to three different families. Based on DNA analysis, river dolphins diverged from their common cetacean ancestors on at least three occasions, first in India, then in China and South America, before sea dolphins. The evolution of each of the families proceeded independently and in parallel - geographically isolated and genetically different kinds, adapting to similar conditions, eventually acquired similar characteristics. Every spring gives Amazonian dolphins a chance to escape the narrow borders. riverbed and remember the ancient boundless homeland. Tony Martin of the University of Kent in England has been studying dolphins in nature reserve Mamirahua in western Brazil for 16 years now. Here, two tributaries of the Amazon flood thousands of square kilometers of jungle for half a year, turning them into a huge lake under tree cover. Martin and his Brazilian colleague Vera da Silva found that female dolphins swim deeper into the forest - possibly hiding from aggressive hot pink males. Females are mostly gray in color; but the males, according to Martin and da Silva, acquired their cute pink color as a result of multiple wounds. “There are no scars on large males,” says Martin. “They fight furiously not for life, but for death: they bite off each other’s jaws, tails, fins, tear apart the blowholes.” There are few bright pink males, but it is they who have the greatest success with females - at least during mating season when the water returns to the river bed and the females are forced to swim back from the dense jungle. Pink color is not the only way to attract a female. Sometimes a bowto takes a bunch of plants or a piece of wood in its beak, starts spinning and hitting its prey on the water. The locals thought for a long time that this was just a game, until Martin discovered that only males hold objects in their mouths - and only in the presence of females. In addition, during this demonstration, the probability of a fight among males increases 40 times. It turns out that boutos, trying to impress their friends, brag about things they don’t need in general. “It's like some guy showing off with his Ferrari,” explains Martin. By the way, besides dolphins, only monkeys and humans use items for boasting. Martin believes that only about 100,000 Amazonian dolphins remain in nature, and they are in great danger. In seven years, the population from the Mamiraua Reserve has halved. Fishermen use dolphin meat as bait for catfish, and it is not uncommon for bowtos to accidentally get caught in nets and suffocate, unable to surface. According to ancient local beliefs, bowto - magical creature capable of changing its appearance. Sometimes it comes out of the river in the form of a man to lure gullible men and women into a fabulous underwater kingdom. It is even said that dolphins wear hats so that their blowhole and bulbous head cannot be seen. But, alas, no less rich Chinese myths did not help the white dolphins of the Yangtze. How to save the boutos from the fate of their relatives?
The Amazonian dolphin, also called inia or bowto, is the largest river dolphin. Inia geoffrensis, as scientists call it, reaches 2.5 meters in length and weighs 2 centners. Light gray juveniles lighten with age. The body of the Amazonian dolphin is full, with a thin tail and a narrow muzzle. A round forehead, a slightly curved beak and small eyes are the features of this species of dolphins.
There is an Amazonian dolphin in the rivers and lakes of Latin America. In accordance with the distribution area, scientists divide the species into three subspecies: Inia geoffrensis geoffrensis, Inia geoffrensis boliviensis and Inia geoffrensis humboldtiana.
Amazonian dolphins live throughout the Amazon basin, even in small rivers and lakes. They usually do not change their place of residence, except seasonal migration. When the water level drops in the river, the ini look for a deeper channel. If the river floods, then dolphins can move to the flooded plains. During the rainy season, Amazonian dolphins have the opportunity to swim from the bed of one river to the basin of another.
These dolphins do not form groups. It is quite rare to see a flock of several dolphins, this happens only during breeding. Since they do not form groups, they do not have a hierarchy. Inii lead an active lifestyle day and night. Compared to other dolphins, these swim at a slower speed, up to 3 km/h on average. The maximum speed of the Amazonian dolphin is 22 km/h. They can dive and stay underwater for up to 2 minutes. When swimming, the inias are excellent at maneuvering.
Amazonian dolphins feed on small fish, they can eat up to 12 kg of food per day. They eat different types fish, and the structural features of the jaw allow you to feast on turtles and crabs.
Amazonian dolphins hunt near the coast, near river mouths or near waterfalls. In these places, the water is quite muddy, and the fish does not have time to escape from the hunter. In addition, dolphins get food from the bottom, digging it out of the silt, steal fish from fishing nets. Sometimes the Amazonian dolphin goes hunting together with a giant otter or a tukashi dolphin. Although dolphins have good eyesight, they rely on hearing as well as touch to hunt, using the echolocation method.
Living in nature, Amazonian dolphins love to play and are curious about their surroundings. They do not abandon their relatives who are in trouble, for example, the wounded. Don't be afraid to approach boats. These dolphins can be tamed, but not trained. In captivity, they become aggressive, so they are not kept in aquariums.
Scientists have not fully explored the nature of the reproduction of oysters. There are only suggestions that males enter the battle for the female. After the birth of the cub, the female stays with him for a long time in shallow water, where it is easier for him to float to the surface to breathe. In addition, it is easier to get food here and no dangerous predators. The cub feeds on mother's milk for up to one year, but stays with her longer, up to about three years. The Amazonian dolphin reaches sexual maturity at the age of five. The total lifespan of the oysters is unknown; in captivity, they do not survive more than 33 months.
Amazon Dolphin Playing important role in the ecosystem. He is a hunter for a number of fish species, and also serves as food for black caimans, blunt-nosed sharks, and.
Man does not hunt Amazonian dolphins. However, some fishermen kill these animals due to damage to their fishing nets. The laws of Latin American countries prohibit or restrict the capture of the Amazonian dolphin. Despite the deterioration environment, the number of Amazonian dolphins is not decreasing.
Located in southwestern Louisiana, USA salt Lake Kalsasyu. In 2009, the captain of a local shipping company, Eric Rui, discovered and photographed a rare pink bottlenose in the waters of the lake. Apparently, this is the only representative in the world that has such a rare color in nature. According to Captain Rui, a unique animal always appears on the surface in the company of four more relatives, one of which, apparently, is his mother, who does not want to let go of her offspring.
Unusual is quite socialized. Its behavior is no different from the behavior of other animals of this species. It is only noticed that it appears less often and remains on the surface somewhat longer than other individuals. According to scientists, the dolphin is quite healthy, and its unusual color is not at all the result of an unfavorable environmental situation or harmful solar radiation. A unique animal looks at the world with red eyes, which indicates albinism.
Albinism is a fairly rare genetic trait characterized by the congenital absence of melanin, a substance that determines the color of the eyes, skin and hairline.
So, the unique pink dolphin, according to experts, is an albino, although it is completely unclear how he inherited such a rare genetic quality.
Pink Amazon Dolphins
However, if we talk about the rare coloration of cetaceans, the glamorous dolphin is not as lonely as it might seem. Inii, or Amazonian river dolphins, are fawn-gray and white. With age, their body becomes pinkish or bluish in color. How did it happen that dolphins, the original inhabitants of salt waters, settled in rivers?
It is assumed that 15 million years ago the level of the World Ocean was higher. Huge areas of present-day South America were under water. When the ocean receded, the dolphins remained in their former territories.
River dolphins are different from the well-known ocean dolphins. They have a strongly elongated leathery snout resembling a beak. The main difference is that the neck vertebrae of the river dolphin are not fused and the head can turn at an angle of 90 degrees. relative to the body. This is very convenient when swimming between flooded trees, of which there are many in the Amazon and its tributaries.
The branch of river dolphins separated earlier than others from the common ancestor of cetaceans and developed independently. Therefore, along with common features they have some features that distinguish them from the ocean representatives of dolphins.
Amazonian pink dolphins are slower than their counterparts. The usual speed of movement is 3-4 km / h, and the maximum is about 18. Amazonian inia playful and curious, easily tamed, but difficult to train. Therefore, they are rarely seen in aquariums. Dolphins are considered sacred by the locals. Following the dolphins, fishermen find schools of fish. In addition, the inia disperse piranhas.
River pink dolphins in major rivers South America - the Amazon, Orinoco, which flow through the territory of Bolivia, Peru, Brazil, Venezuela, Colombia, Guiana. River Amazon dolphins are listed in the International Red Book as an endangered species.
The Amazon Dolphin is most large view river dolphins, usually they grow to two and a half - three meters in length and reach a weight of more than two hundred kilograms. Everyone who has ever met a bouto and seen them live noted that they are plump, and the muzzle and tail are rather narrow. What is strange with such a volume of the body. Boutos have a steep, rounded forehead, a long beak curved upwards, covered with stiff bristles above and below.
Nature knows how to surprise, despite the fact that we have already seen a lot in our lives, we are familiar with various wonderful and unusual creatures of flora and fauna live or from photos, there are still animals that can surprise even sophisticated zoologists with their existence. One of prominent representatives such miraculous beasts is the Amazonian river dolphin. This species also bears such names:
- Amazonian inia.
- Buto.
- White river dolphin.
- Pink dolphin.
Yes, the Amazonian hoarfrost has many names, but they all boil down to the fact that their owner is a river mammal, a dolphin with an unusual color.
It is almost impossible to see such an animal live. In an aquarium or zoo, pink dolphins are not able to live longer. three years. Thus, it turns out that they die before they even reach puberty. This suggests that they do not breed in captivity.
Yes, and keeping such dolphins is not very profitable: they will not be able to participate in various shows for spectators. After all, despite the fact that boutos easily converge with people and are tamed, they are absolutely not amenable to training and refuse to perform even the simplest tasks or tricks. In addition, the nature of these wonderful creatures deteriorates greatly in captivity and they become terribly aggressive towards people and fellows.
Outwardly, Amazonian river dolphins are very different from other species of these mammals. Main Feature bowto is a color change skin depending on age. The color of such an animal is very diverse in its variations. You can meet river dolphins from bright red tones to very dark shades.
Usually, the body of the Amazonian inia is bluish in color from above, and reddish or pink below. With age, the color becomes lighter and lighter.
Nature rewarded the pink dolphin large quantity teeth, usually more than a hundred. The main part of the diet of the bowto is solid food, so their teeth wear out quickly and are not very sharp.
One more hallmark of this species of dolphins are their eyes. They are completely small size and consist of the cornea and lens, stained in yellow. Thus nature protected the eyes of the bowto from the bright sunlight Amazon.
Well developed and quite Long neck allows the ini to turn its head, and the hump on the back replaces the upper fin. These dolphins have very thick cheeks, which means they have to search the bottom for food by swimming belly up. So they get the opportunity to see what is happening under water.
Lifestyle
These wonderful creatures live on the mainland of South America, in the Amazon River basin and in its entire river system of sources and tributaries.
You can meet the Amazonian dolphin in reservoirs:
- Bolivia.
- In the north of Peru.
- Brazil.
- Venezuela.
Some tributaries of the Amazon have their origin in the Orinoco River, so bowos are often seen there as well. AT Latin America the population of these animals is also widespread, the size of rivers or lakes is not of great importance to them.
It is worth noting that the habitats of pink dolphins are as fabulously beautiful as the animals themselves. The waters of the Amazon are not transparent, but white as milk. This color gives the river great amount mud at the bottom. Also, this river is the habitat of the largest water lily in the world, bearing the names of Victoria Regia or Victoria Amazon. Along the banks of the Amazon grow a variety of unusual tropical plants and trees, as well as many palm trees.
AT natural environment Amazonian dolphins tend to spend their entire lives in only one place; only seasonal drops in the water level can force them to move to another part of the river or to another body of water. In such cases, they go in search of a place where the channel is deeper. When river system returns to normal, they return home.
After heavy rainfall rivers often overflow their banks and overflow into coastal zones. In such cases locals can often observe frolicking boats in flooded areas. During the rainy season, some individuals may move to another river.
Unlike sea dolphins living in packs, Amazonian dolphins are loners. They gather only during the mating season.
Sometimes you can see two such dolphins together - this is a mother and her cub.
The reproductive biology of this species is still poorly understood. There are suggestions that the bowto are polygamous creatures. This conclusion was made on the basis of sexual dimorphism. Also, one of the signs of polygamy is aggressive skirmishes between males for the possession of a female. Fights are repeated every mating season and leave fighting marks on the skin of males: bites and abrasions.
After the end of the breeding season, the males return to where they came from for mating, while the females remain in the channels or in flooded areas and wait for the cub to appear. The pregnancy of the pink dolphin lasts about eleven months, the birth takes place within four to five hours. After the baby dolphin is born, the female herself pushes him to the surface so that he can take his first breath. Immediately after birth, the cub has a body length of seventy - eighty centimeters and a weight of six to eight kilograms.
Females with dolphins prefer to stay in shallow water as long as possible. The choice of such a place habitat due to a number of advantages.
- Calm water, the absence of a strong current, which the baby may not be able to handle.
- There are no aggressive males nearby.
- A large number of variety of food and lack of competition from other animals.
- No natural enemies.
- The shallow depth allows the cub to independently and easily float to the surface to take in air.
females feed their cubs throughout the year from the moment they are born, but stay close to their mother for about three years. Usually, fifteen to thirty-six months pass between births in pink dolphins. It is not uncommon for a lactating female to be pregnant again.
Sexual maturity in Amazonian dolphins occurs by the fifth year after birth. At this point, the body length of females is one and a half - two meters, in males from two or more meters.
The lifespan of a bowto in its natural environment is this moment not yet known, but when kept in captivity, they rarely live beyond thirty-three months.
As Amazonian dolphins are solitary, they do not have a hierarchical division among their brethren. But this does not prevent them from sometimes communicating with each other. To do this, dolphins use about ten to twelve different sounds, reminiscent of high-pitched calls, barks, clicks, squeals and echolocation.
Bowto are very active creatures, regardless of the time of day they are always alert and busy swimming, socializing or looking for food. Representatives of this species swim quite slowly, maximum speed, which they are able to develop three kilometers per hour. But any most modern boat cannot be compared with them in terms of maneuverability.
When diving, under water, the inia can last up to two minutes. Thus, they break the silt at the bottom to find hiding fish or crabs. Pink dolphins prefer to get food off the coast, in the mouths of the river or near waterfalls. Of course, the water in these places cannot boast of purity and transparency, so the bowto rely more on echolocation and hearing than sight.
Amazonian dolphins eat about twelve kilograms of food per day.. Usually these are small fish, but turtles and crabs are also in demand among these creatures, and they will not refuse to eat them, even if they are full. Such a "brutal" appetite explains the excessive fullness of the bowto.
Sometimes inias team up with dolphins - tukashi or large otters to drive a large school of fish, and then divide the prey among the hunters.
Role in the ecosystem
Pink dolphins play a large role in maintaining the ecosystem of the rivers of South America. Eating various types of fish and even piranhas, they restrain the uncontrolled reproduction of these creatures. Bowto never leave relatives in trouble and help them recover from their wounds.
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