These marine mammals are the smallest of the cetaceans. Today, scientists have about fifty species of dolphins.
Description
These marine inhabitants belong to the subfamily of mammals, order of cetaceans, family of dolphins. 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. As well as a muzzle elongated into a “beak” and a huge number of teeth (more than 70).
Dolphins in the sea navigate using echolocation. Animals have very subtle hearing - sound vibrations from several tens of Hz to 200 kHz are available to them.
Dolphins are endowed with a complex voice signaling and a sound signal, echolocation organ located in the nostril (the only one). Associated with it are six air sacs that have a system of muscles. The frequency of 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 cerebral hemispheres have numerous convolutions (the dolphin's cerebral cortex 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, anti-turbulent properties and the 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 supporters of bionics for decades.
These cute animals are kept in many dolphinariums and oceanariums, as they are easy to learn and train. Today, many species of dolphins "work" in the circus. The possibility of domesticating certain species of these animals is now being considered.
Unfortunately, in many countries they are the subject of fishing (for example, short-headed dolphins in Japan, prodolphins). 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 types of these marine life.
Bottlenose dolphin, or big dolphin
This is the most common and most studied species, which is often kept in the Black Sea aquariums. The bottlenose dolphin is a dolphin that endures captivity more easily than others.
These marine mammals grow up to 3 meters and gain weight of 300 kilograms. This Black Sea dolphin is active during the daytime, it rests at sunset.
Bottlenose dolphins hunt for fish, but they will not refuse shrimps, squids, cephalopods. Hunting for schooling fish, dolphins unite in groups. Looking for stingrays and mollusks, they descend to a depth of more than 300m.
The 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. Humans cause significant damage to the population. In fishing nets, animals often get entangled and die. Echo sounders of sea vessels are also involved in the death of dolphins. The fact is that they are guided by the so-called locator.
Underwater, the sounds of dolphins, propagating at high speed, are reflected from 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 can get lost in space. Often they jump out onto the shallows. There are many such examples, such cases quite often occur on the routes of sea vessels.
Dolphin Sounds
Ichthyologists, studying bottlenose dolphins, found out 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 there are 17 sounds in the "lexicon" of bottlenose dolphins. When chasing their prey, they "bark", when they absorb food - "meow", and when they intend to intimidate an opponent, they make sounds resembling claps. Five of them understand the Black Sea dolphins, the common dolphin and the pilot whale. The remaining 12 sounds are completely unique. Trainers claim that various combinations of these signals allow animals to communicate with humans.
Reproduction of bottlenose dolphins
In spring and summer, the mating season begins for dolphins. At this time, the animals behave quite differently than usual.– they bend their whole body, take special poses, sniff each other, jump, stroke each other with fins and heads, squeal.
The smallest mature female measured by ichthyologists has a body length of 228 cm. Pregnancy lasts about a year.
Bottlenose dolphin, like most cetaceans, is a viviparous animal. The baby is born in the water, usually tail first. Childbirth sometimes lasts 20 minutes, and sometimes drags on for two hours.
Common 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 two thousand individuals.
White flanks create families consisting of several generations of offspring of the same female. Lactating females with young and males sometimes form separate, often temporary schools.
These are the fastest marine animals, reaching speeds of up to 60 km/h. Which is easy enough to explain. The dolphin is a small dolphin. The length of his body does not exceed one meter. Even a shark can't keep up with them.
Flocks of dolphins live mainly in the open sea. They feed on fish, molluscs, and sometimes crustaceans.
Habitat
It is generally accepted that this dolphin is from the Black Sea, although it lives in almost all seas and oceans with temperate or warm waters. According to scientists, the common dolphin that lives in the Black Sea is the standard of “dolphin beauty.”
ExternalFeatures
This animal has a proportional, slender body. On the sides there is a rather complex pattern - a horizontal eight on a white background, which gave the name to the species. Color - black with white, as well as various shades of gray.
Behavior in nature
White flanks are very friendly animals in one flock. They take care of sick fellows, jointly hunt fish, protect and protect young dolphins. Communication in the flock occurs with the help of sound signals - clicks, squeaks and rattles. Unlike the bottlenose dolphin, the common dolphin uses 5 sounds of different frequencies, tonality and timbre.
In winter, dolphins gather in large flocks, reaching several thousand individuals. By the summer, they usually disintegrate, and the white flanks form small groups. In such families, there is a very close connection between all its members.
There have been reports of these dolphins helping old animals float on the surface of the water so they can breathe.
Dolphin azovka
This variety has several names - Azov dolphin, common porpoise, ingot, Azov porpoise, etc. This is another (of the three most common) Black Sea dolphins.
External differences
The Black Sea Azovka dolphin has a short head with a blunt, rounded muzzle with a powerful fat pad. The body of the dolphin has a cigar-shaped shape, a triangular dorsal fin with a wide base. The pectoral fins are slightly rounded. The back is painted dark gray, the belly is almost white. The length of thisthe animal does not exceed 1.8 m. Its weight is 30 kg.
Habitat
Dolphin Azovka near the Black Sea is found throughout the year, off the coast of Azov appears in early spring. In autumn, these animals leave after schools of atherine and anchovy.
In some years, a sharp cooling and even glaciation of the Sea of \u200b\u200bAzov led to the death of these animals in the ice.
They usually winter off the coast of the Caucasus and Southern Crimea. These dolphins live in small groups of 5 to 30 individuals, but there are also loners (quite rare).
In the summer, you can see the Azovka in the Kerch Strait, where they hunt for mullet. This dolphin often enters rivers.
Life expectancy - 12 years, puberty occurs by 4 years. Pregnancy lasts approximately 11 months, cubs are born in May-August. The female feeds offspring for 5-6 months.
Azovka feeds on gobies, anchovies, slats and other small fish. Dolphin Azovka eats more than 5 kg of fish every day.
