A graceful body, a smiling face, immense curiosity for a person and a cheerful disposition — yes, it’s all bottlenose dolphin. Dolphin, as many used to call it a smart mammal. With a person, he develops the most good-neighborly relations. Today, there are already dolphinariums in every seaside town, where everyone can realize the dream of swimming with dolphins at a reasonable price. But is the bottlenose dolphin really cute and harmless?
Species origin and description
Photo: bottlenose dolphin
The topic of the origin of marine mammals is very intriguing. How did these animals end up living in the deep sea? It is not easy to answer this question, but there are several assumptions about the accomplishment of this event. They all boil down to the fact that hoofed ancestors, eating fish, spent more and more time in the water in search of food. Gradually, their respiratory organs and body structure began to change. This is how ancient whales (archaeocetes), baleen whales (mystacocetes), and toothed whales (odonocets) appeared.
Modern sea dolphins are descended from a group of ancient toothed whales called the Squalodontidae. They lived during the Oligocene period, but only in the next Miocene period, about 20 million years ago, 4 families emerged from this group, which exist to this day. Among them were river and sea dolphins with three of their subfamilies.
The species of bottlenose dolphins or bottlenose dolphins (Tursiops truncatus) comes from the genus Tursiops, the Dolphin family. These are large animals, 2.3-3 m long, some individuals reach 3.6 m, but quite rarely. The weight of bottlenose dolphins varies from 150 kg to 300 kg. A characteristic feature of dolphins — developed “beak” on a long, almost 60 cm, skull.
The thick fat layer of the dolphin’s body provides it with thermal insulation, but these mammals do not have sweat glands. That is why fins are responsible for the function of heat exchange with water: dorsal, pectoral and caudal. A beached dolphin’s fins overheat very quickly and, if it is not helped by moisturizing them, they simply stop working.
Appearance and features
Photo: bottlenose dolphin
The body color of bottlenose dolphins is rich brown above, and below — much lighter: from gray to almost white. The dorsal fin is high, at the base it widens considerably, and has a crescent-shaped notch at the back. The pectoral fins also have a wide base and then taper into a sharp tip. The anterior edges of the fins are thicker and more convex, while the posterior ones, on the contrary, — thinner and more concave. Black Sea bottlenose dolphins have some color features. They are even divided into two groups. The first is characterized by a clear line between the dark area of the back and the light abdomen, and near the dorsal fin they have a light triangle, the apex pointing towards the fin.
The other group does not have a clear boundary between the light area and the dark area. The coloration in this part of the body is blurred, has a smooth transition from dark to light, and there is no light triangle at the base of the dorsal fin. Sometimes the transition has a border in the form of a zigzag. There are several subspecies of bottlenose dolphins, they are distinguished on the basis of their habitat and some features of the body structure or color, as in the case of the Black Sea:
- Common bottlenose dolphin (T.t.truncatus, 1821);
- Black Sea bottlenose dolphin (T.t.ponticus, 1940);
- Far Eastern bottlenose dolphin (T.t.gilli, 1873).
Indian bottlenose dolphin (T.t.aduncus) — some scientists consider it a separate species, as it has more pairs of teeth (28 instead of 19-24x). The lower jaw of bottlenose dolphins is more elongated than the upper. There are a lot of teeth in the dolphin’s mouth: from 19 to 28 pairs. On the lower jaw they are less by 2-3 pairs. Each tooth is a sharp cone, 6-10 mm thick. The location of the teeth is also interesting, they are placed in such a way that there are free spaces between them. When the jaw closes, the lower teeth fill the upper gaps, and vice versa.
An animal’s heart beats an average of 100 times per minute. However, with great physical exertion, it gives all 140 strokes, especially when developing maximum speed. Bottlenose dolphins have a speed of at least 40 km/h, and they are also capable of jumping 5 meters out of the water.
Bottle dolphin voice box — this is another amazing thing. Air sacs (there are 3 pairs in total), interconnected by nasal passages, allow these mammals to make various sounds with a frequency of 7 to 20 kHz. In this way they can communicate with their relatives.
Where does the bottlenose dolphin live?
Photo: Black Sea bottlenose dolphin
Bottlenose dolphins are found in almost all warm waters of the world’s oceans, as well as in temperate ones. In the waters of the Atlantic, they are distributed from the southern borders of Greenland to Uruguay and South Africa. In the local seas: the Black, Baltic, Caribbean and Mediterranean, dolphins are also found in abundance.
They cover the Indian Ocean starting from the northernmost, including the Red Sea, then their range extends south to South Australia . Their population occupies the Pacific Ocean from Japan to Argentina, while capturing the state of Oregon all the way to Tasmania.
What does the bottlenose dolphin eat?
Photo: bottlenose dolphins
Fish of different breeds make up the main diet of bottlenose dolphins . They are excellent sea hunters and use different methods to catch their prey. After all, adults should eat 8-15 kg of live food daily.
For example, dolphins hunt a whole flock of fish that lead a diurnal lifestyle:
- anchovy;
- mullet;
- anchovies;
- mullet;
- umbrine, etc.
If there are enough fish, bottlenose dolphins only hunt during the day. As soon as the number of potential food decreases, the animals begin to look for food closer to the seabed. At night, they change tactics.
Bottle dolphins gather in small groups to hunt other inhabitants of the deep sea:
- shrimp;
- sea urchins;
- electric rays;
- flounder;
- some species of sharks;
- octopuses ;
- eels;
- shellfish.
They lead an active lifestyle at night, and bottlenose dolphins have to adapt to their biorhythms in order to get enough. Dolphins love to help each other. They communicate and give special signals with a whistle, not allowing the prey to hide, they surround it from all sides. Also, these intellectuals use their sound signals to confuse their victims.
Character and lifestyle features
Photo: Black Sea bottlenose dolphin
Bottlenose dolphins are adherents of settled life, only sometimes you can find nomadic flocks of these animals. Most often they choose coastal zones. It is understandable where else they can get more food! Since the nature of their food is bottom, they know how to dive great. In the Black Sea, they have to get food from a depth of up to 90 m, and in the Mediterranean, these parameters increase to 150 m.
According to some reports, in the Gulf of Guinea, bottlenose dolphins can dive to a greater depth: up to 400- 500 m. But this is more an exception than a rule. But in the USA they conducted an experiment, during which a dolphin began to dive to 300 m. This experiment was carried out as part of one of the programs of the Navy, it took a long time to achieve results.
During the hunt, the dolphin moves in jerks, often making sharp turns. At the same time, he holds his breath for at least a few minutes, and his maximum respiratory pause can be about a quarter of an hour. In captivity, the dolphin breathes differently, it needs to inhale from 1 to 4 times per minute, while it first exhales, and then instantly takes a deep breath. During the race for prey, they whistle and even emit something similar to barking. When there is a lot of food, they give a feeding signal to others by meowing loudly. If they want to scare one of their own, you can hear clapping. To navigate the terrain or search for food, bottlenose dolphins use echolocation clicks, which painfully resemble the creak of unlubricated door hinges.
Dolphins are active mainly during the day. At night, they sleep near the surface of the water, often opening their eyes for a couple of seconds and closing them again for 30-40 seconds. Tails they deliberately leave in limbo. Weak, unconscious strokes of the fin against the water push the body out of the water for breathing. The inhabitant of the water element cannot afford to fall asleep soundly. And nature made sure that the hemispheres of the dolphin’s brain slept in turn! Dolphins are known for their love of entertainment. In captivity, they start games: one kid teases another with a toy, and he catches up with him. And in the wild, they are very fond of riding the wave that is created by the bow of the ship.
Social structure and reproduction
Photo: bottlenose dolphin
Dolphins have very developed social bonds. They live in large flocks where everyone is related. They readily come to the rescue of each other, and not only in pursuit of prey, but also in dangerous situations. Not uncommon — cases when a flock of dolphins killed a tiger shark that dared to attack a baby bottlenose dolphin. It also happens that dolphins save drowning people. But they do this not out of noble motives, but most likely by mistake, mistaking a person for a relative.
The ability of bottlenose dolphins to communicate has long been exciting scientists, so a lot of research has appeared in this direction. The conclusions from them were simply amazing. Bottlenose dolphins, like people, have character, and can also be “good” and “bad”!
For example, a fun game of throwing a baby dolphin out of the water was interpreted by researchers not from the best side. So adult bottlenose dolphins slaughtered a baby from a strange flock. Examination of a cub that survived after such “games” showed multiple fractures and severe bruises. Chasing a female during “mating games” sometimes looks depressing. The spectacle with the participation of warlike males is more like violence. In addition to “sniffing” and adopting proud poses, they bite the female and squeal. Females themselves try to mate with several males at once, but not out of voluptuousness, but so that all of them subsequently consider the born baby to be their own and not try to exterminate it.
The breeding season for bottlenose dolphins is in spring and summer. The female becomes sexually mature when it reaches a size of more than 220 cm. After several weeks of rutting, as a rule, pregnancy occurs for a period of 12 months. In pregnant females, movements slow down, by the end of the term they become clumsy and not very sociable. Childbirth lasts from a few minutes to a couple of hours. The fetus comes out tail first, the umbilical cord breaks easily. A newborn, pushed by his mother and 1-2 more females to the surface, takes his first breath in his life. At this moment, a certain excitement covers literally the entire flock. The baby immediately searches for the nipple and feeds on mother’s milk every half hour.
The baby does not leave the mother for the first few weeks. Later he will do it without any obstacles. However, breastfeeding will continue for about 20 more months. Although dolphins can eat solid food as early as 3-6 months, as it does in captivity. Sexual maturity occurs at the age of 5-7 years.
Natural enemies of the bottlenose dolphin
Photo: Bottlenose Dolphin
Even such smart and large animals as dolphins cannot live in peace. There are many dangers in the ocean. Moreover, these “dangers” are not always large predators! Young or weakened bottlenose dolphins are preyed upon by catran sharks, which themselves are quite small. Strictly speaking, large predators — this is a much greater danger. Tiger sharks and great white sharks can attack bottlenose dolphins without a twinge of conscience, and with a high degree of probability will emerge victorious from the fight. Although the dolphin has greater maneuverability and speed than the shark, nevertheless, sometimes the mass plays a dominant role.
A shark will never attack a flock of mammals, because this practically guarantees the death of a predator. Dolphins, like no other marine life, can rally in a critical situation. At the very bottom of bottlenose dolphins, dangers can also lie in wait. The stingray with its spike is able to repeatedly pierce a mammal, pierce the belly, lungs, and thereby contribute to its death. The dolphin population suffers significant damage from natural disasters: sudden frosts or severe storms. But even more they suffer from a person. Direct — from poachers, and indirectly — from pollution of the oceans with waste and oil products.
Population and species status
Photo: Black Sea bottlenose dolphin
The exact number of individuals is unknown, but there is information about the number of some individual populations:
- In the northwestern part of the Pacific Ocean, as well as in the waters of Japan — their number is about 67,000;
- The Gulf of Mexico has up to 35,000 bottlenose dolphins;
- The Mediterranean Sea boasts a number of 10,000;
- Off the North Atlantic coast — 11,700 individuals;
- There are about 7,000 dolphins in the Black Sea.
Every year, thousands of dolphins die from human activities: spread nets, shooting, poaching during spawning. Harmful substances that pollute the waters of the world’s oceans enter the tissues of animals, accumulate there and provoke many diseases and, most importantly, miscarriages in females. A film of spilled oil can completely block the breath of bottlenose dolphins, from which they die a painful death.
Another man-made problem — constant noises. Arising from the movement of ships, such a noise screen spreads over vast distances and makes it difficult for bottlenose dolphins to communicate and their orientation in space. And this interferes with normal food production and also causes disease.
Nevertheless, the conservation status of bottlenose dolphins — LC, he indicates that there is no concern for the bottlenose dolphin population. The only subtype that causes such concern is — These are Black Sea bottlenose dolphins. They are listed in the Red Book of Russia and are in the third category. Catching dolphins has been banned since 1966. These smart animals with a cheeky smile (the secret is in fatty deposits on the cheeks) are very mysterious. Their incredible abilities and unusual behavior for marine life are intriguing. Admiring the bottlenose dolphins in the aquarium, you can get aesthetic pleasure from their contemplation. But still, the bottlenose dolphin must be in the open sea, warm and clean, so that the number is preserved and multiplied.
