These marine mammals are the smallest of the cetacean order. Today, scientists have about fifty species of dolphins.
Description
These marine inhabitants belong to the subfamily of mammals, the order of cetaceans, and the dolphin family. Their body length ranges from 1.2 to 3 meters, in some species it reaches 10 m. Almost all species of dolphins have a fin on their backs. And also a muzzle extended into a “beak” and a huge number of teeth (over 70).
Dolphins in the sea are guided by echolocation. Animals have a very delicate hearing - they can hear sound vibrations from several tens of Hz to 200 kHz.
Dolphins are endowed with a complex voice signaling and sound-signal, echolocation organ located in the nostril (the only one). Six air sacs having a muscle system are associated with it. The frequency of the emitted signals is about 170 kHz.
It is necessary to say about the highly developed central nervous system of these animals - the brain is large, spherical, its large hemispheres have numerous convolutions (the cerebral cortex of the dolphin has 30 billion nerve cells). Such brain sizes allow dolphins to process a large amount of incoming information: they can, like parrots, copy the words that a person says.
The hydrodynamic shape of the body, the anti-turbulent properties and structure of the skin, the hydroelastic effect (adjustable) in the fins, the unique ability to dive to great depths and many other features of dolphins have been of interest to proponents of bionics for decades.
These cute animals are kept in many dolphinariums and aquariums, as they are easy to learn and trainable. Today, many species of dolphins "work" in the circus. The possibility of domestication of certain species of these animals is being considered.
Unfortunately, in many countries they are subject to fishing (for example, short-headed dolphins in Japan, dolphins). In our state, the fishing of these animals was banned back in 1966.
The topic of our conversation today is the Black Sea dolphin. We will introduce you to the three main species of these marine life.
Bottlenose dolphin or big dolphin
This is the most common and most studied species, which is often found in the Black Sea aquariums. Bottlenose dolphin is a dolphin that is easier than others to carry captivity.
These marine mammals grow up to 3 meters and gain weight in 300 kilograms. This Black Sea dolphin is active in the daytime, it rests at sunset.
Bottlenose dolphins hunt for fish, but they will not refuse shrimps, squids, cephalopods. When hunting for schooling fish, dolphins come together in groups. Looking for stingrays and mollusks, they descend to a depth of more than 300 m.
Bottlenose dolphin is a dolphin that consumes more than 15 kilograms of fish daily. They have few enemies - these are large killer whales and sharks. Significant damage to the population causes a person. In fishing nets, animals often become entangled and die. Sounders of sea vessels are also involved in the death of dolphins. The fact is that they are guided with the help of the so-called locator.
Under water, dolphin sounds, propagating at high speed, bounce off objects and come back. Thus, the animal receives information about the object of interest to him. If he feels the “alien” sound wave of the echo sounder, he may be lost in space. Often they jump out to the sandbank. There are many such examples; similar cases quite often occur on the routes of ships.
Dolphin sounds
Ichthyologists, studying bottlenose dolphins, found that they differ in a wide range of sounds that they use to communicate within the flock. After analyzing the recordings of “negotiations”, scientists came to the conclusion that in the “vocabulary” of bottlenose dolphins there are 17 sounds. In pursuit of their prey, they “bark” when they absorb food - “meow”, and when they intend to intimidate an opponent, they make sounds that resemble pops. Five of them understand the Black Sea dolphins dolphin and grind. The remaining 12 sounds are completely unique. Trainers argue that various combinations of these signals allow animals to communicate with humans.
Breeding bottlenose dolphins
In spring and summer, dolphins mating season begins. At this time, the animals behave quite differently than usual - they bend with their whole bodies, take special poses, sniff each other, jump, stroke each other with fins and heads, screech.
The smallest sexually mature female, which was measured by ichthyologists, had a body length of 228 cm. Pregnancy lasts about a year.
Bottlenose dolphins, like most cetaceans, are a viviparous animal. A baby is born in the water, usually with its tail forward. Childbirth sometimes lasts 20 minutes, and sometimes drag on for two hours.
Moth - an ordinary dolphin
These are the most social animals of their family. They do not imagine their life alone. A flock of dolphins in some cases reaches the number of two thousand individuals.
Squirrels create families consisting of several generations of offspring of the same female. Nursing females with young and males sometimes form separate, often temporary, schools.
These are the fastest marine animals, developing speeds of up to 60 km / h. Which is easy enough to explain. Squirrel is a small dolphin. The length of his body does not exceed one meter. Not even a shark can keep up with them.
Flocks of dolphins live mainly in the open sea. They feed on fish, shellfish, and sometimes crustaceans.
Habitat
It is generally accepted that this dolphin is Black Sea, although it lives in almost all seas and oceans with temperate or warm waters. According to scientists, the white barrel living in the Black Sea is the standard of "dolphin beauty."
External features
This animal has a proportional, slender body. On the sides is a rather complex pattern - a horizontal figure eight on a white background, which gave the name a look. Color - black with white, as well as various shades of gray.
Nature behavior
Squirrels are very friendly animals in one flock. They take care of sick brothers, hunt fish together, protect and protect young dolphins. Communication in the flock occurs with the help of sound signals - clicks, squeak and rattle. Unlike bottlenose dolphins, the white barrel uses 5 sounds of different frequencies, tonality and timbre.
In winter, dolphins gather in large flocks, reaching several thousand individuals. By summer, they usually disintegrate, and the whiskers create small groups. In such families there is a very close relationship between all its members.
Cases have been recorded when these dolphins helped old animals stay on the surface of the water so that they could breathe.
Dolphin Azovka
This variety has several names - Azov dolphin, common porpoise, pig, Azov porpoise, etc. This is another (of the three most common) Black Sea dolphin.
External differences
Dolphin Black Sea Azovka has a short head with a blunt, rounded muzzle, which has a powerful fat pad. The body of the dolphin has a cigar-shaped, triangular dorsal fin with a wide base. The pectoral fins are slightly rounded. The back is painted in dark gray, the belly is almost white. The length of this animal does not exceed 1.8 m. Its weight is 30 kg.
