There are a lot of special and memorable things in nature. Among the inhabitants of the seas, one interesting fish, namely the flying fish, serves as an example. Of course, children immediately imagine a flying fish over the city, scientists think about the anatomy and origin of this species, and someone will probably remember small tobiko caviar, which is used in the preparation of sushi and rolls. At the beginning of the 20th century, flying fish attracted the attention of specialists in the aerodynamic industries, like small living models of aircraft.
Origin of the species and description
Flying fish differ from their non-flying relatives mainly in the structure of their fins. The family of flying fish includes more than 50 species. They do not flap their “wings”, they only lean on the air, but during the flight the fins can vibrate and flutter, which creates the illusion of their active work. Thanks to their fins, fish such as gliders are able to fly distances from several tens to hundreds of meters in the air.
Adherents of the theory of evolution believe that one day, ordinary fish appeared individuals with fins slightly longer than their usual ones. This allowed them to use them as wings, jumping out of the water for a few seconds and escaping predators. Thus, individuals with elongated fins turned out to be more viable and continued to develop.
Video: Flying fish
However, the finds and discoveries of paleontologists demonstrate the fossils of flying fish from the Cretaceous and Triassic. The structure of the fins in the specimens does not correspond to living individuals, but it has nothing to do with the intermediate chains of evolution either. Moreover, no fossils with partially enlarged fins have ever been found.
Recently, the imprint of an ancient flying fish was discovered on the territory of modern China. According to the structure of the skeleton, it was revealed that the fish Potanichthys Xingyiensis belongs to the already extinct group of thoracopterids. Its age is about 230-240 million years. It is believed that this is the oldest fish with flying ability.
Modern individuals belong to the Exocoetidae family and occurred only 50 million years ago. Scientists suggest that the individuals of these two families are in no way connected by evolution. A typical representative of dipterous flying fish is Exocoetus Volitans. Four-winged flying fish are more numerous, united in 4 genera and more than 50 species.
Appearance and features
Individuals of flying fish, regardless of species, have a very small body, on average 15- 30 cm in length and weighing up to 200 grams. The largest individual found reached 50 cm and weighed just over 1 kg. They are elongated and flattened from the sides, this allows them to be streamlined during the flight.
The main difference among the fish within the family is in their fins, more precisely in their number:
- Diptera flying fish have only two wings-fins.
- In addition to pectoral fins, four-winged fins also have smaller ventral fins. It is the four-winged fish that achieve the highest flight speeds and longest distances.
- There are also “primitive” flying fish with short pectoral fins.
The main difference between the family of flying fish and others lies in the structure of the fins. They occupy almost the entire length of the body of the fish, have a larger number of rays and are quite wide when unfolded. The fins of the fish are attached closer to its upper part, near the center of gravity, which allows you to better keep your balance during the flight.
The caudal fin also has its own structural features. First, the spine of the fish is curved downwards towards the tail, so the lower lobe of the fin is slightly lower than in other families of fish. Secondly, he is able to make active movements and work as a motor, while the fish itself is in the air. Thanks to this, she is able to fly, relying on her “wings”.
The swim bladder is also endowed with an excellent structure. It is thin and stretched along the entire spine. Probably this arrangement of the organ is due to the need for fish to be thin and symmetrical in order to fly like a spear.
Nature also took care of the color of the fish. The upper part of the fish along with the fins is bright. Usually blue or green. With such a coloration from above, it is difficult to notice birds of prey. The belly, on the contrary, is light, gray and inconspicuous. Against the background of the sky, it is also advantageously lost, and it is difficult for underwater predators to notice it.
Where does the flying fish live?
Flying fish inhabit the near-surface strata of warm seas and oceans in tropical and subtropical latitudes. The boundaries of the habitats of individual species depend on the seasons, especially in areas of boundary currents. In summer, fish can migrate long distances to temperate latitudes, so they are found even in Russia.
Flying fish do not live in cold waters where the temperature drops below 16 degrees. Temperature preferences depend on specific species, but usually fluctuate around 20 degrees. In addition, the distribution of some species is influenced by the salinity of surface waters, the optimal value of which is 35‰.
Flying fish are more likely to stay in coastal areas. But some species also live in open water, and approach the shores only during spawning. All this is closely related to the method of reproduction. Most species need a substrate to which they can attach their eggs, and only a few species of diptera flying fish belonging to the genus Exocoetus lay eggs, which then float in open water. Only such species are found among the oceans.
What do flying fish eat?
Flying fish are not predatory fish. They feed on plankton in the upper layers of the water. Plankton has its own biorhythms, it rises and falls during the day in different thicknesses. Therefore, flying fish choose those places where plankton is carried by currents, and gather there in huge schools.
The main source of nutrients is zooplankton. But also eat:
- microscopic algae;
- larvae of other fish;
- small crustaceans such as krill and euphausiids;
Fish swallow small organisms by filtering the water with their gills. Flying fish have to share food with competitors. These include swarms of anchovies, schools of saury and mackerel pike. Nearby, whale sharks can eat plankton, and sometimes the fish themselves become food captured along the way.
Peculiarities of character and lifestyle
Thanks to the peculiar fins, both pectoral and caudal, flying fish are well adapted to life in the near-surface parts of the ocean. Their most important feature is the ability to partially overcome distances by air. When moving from one place to another, they periodically jump out of the water and fly meters above the surface of the water, even if none of the predators threatens their lives. In the same way, they are able to jump out when danger approaches from hungry predatory fish.
Sometimes fish prolong their flight with the help of the lower part of the caudal fin, as if vibrating it, pushing off several times. Usually the flight takes place directly above the surface of the water, but sometimes they take it steeply up and end up at a height of 10-20 meters. Often sailors find fish on their ships. They react to bright light and rush at it in the dark, like moths. Some of them crash into the side, some fly over, but some fish are less lucky, and they die falling on the deck of the ship.
In the water, the fins of flying fish are quite tightly pressed to the body. With the help of powerful and fast movements of the tail, they develop high speeds in the water up to 30 km/h and jump out of the surface of the water, then spreading their “wings”. Before jumping in a semi-submerged state, they can increase their speed to 60 km/h. Usually the flight of flying fish does not last long, about a few seconds, and they fly about 50-100 meters. The longest recorded flight was 45 seconds, and the maximum distance recorded in flight — 400 meters.
Like most fish, flying fish live in small flocks in the waters. Usually up to a couple of dozen individuals. Within the same flock there are fish of the same species, close in size to each other. They also move together, including making joint flights. It looks like a flock of huge dragonflies flying over the surface of the water along a flat parabola. In places where the number of flying fish is quite high, whole shoals are formed. And the most abundant food areas are inhabited by countless shoals. There, the fish behave more calmly and stay in the water as long as they feel that they are not threatened.
Social Structure and Reproduction
One way to increase survival is to form groups of 10-20 individuals. Usually flying fish live in small groups, but sometimes they can form larger compounds up to several hundred pieces. In case of danger, the whole flock quickly flees from the predator, so only a few of all the fish are eaten, while the rest continue to stick together. Fish have no social differentiation. None of the fish plays the role of master or slave. Most species breed throughout the year. But some only in a certain period, usually from May to July. At this time, during the coastal spawning of flying fish, you can observe muddy greenish water.
Depending on the species, flying fish breed in different parts of the seas and oceans. The reason for the differences is that their eggs are differently adapted to spawning. Most species spawn equipped with long sticky filaments, and these need a substrate to attach the eggs, and coastal areas have a lot of suitable material. But there are species that spawn on floating objects, on algae, such as surface algae, tree debris, floating coconuts, and even other living creatures.
There are also three species of Diptera fish of the Exocoetus family, which live in the open ocean and do not migrate even during spawning. They have floating eggs and therefore they do not need to get close to the shore in order to procreate.
Males usually stay together with females. During spawning, they also perform their task, usually several males are chasing the female. The most agile douse eggs with seminal fluid. When the fry hatch, they are ready to live on their own. Until they grow up, they are in more danger, but nature has provided them with small antennae near the mouth, which help them to disguise themselves as plants. Over time, they will take on the appearance of normal adult fish, and reach the size of relatives of about 15-25 cm. The average life expectancy of flying fish is about 5 years.
Natural enemies of flying fish
On the one hand, the ability to be in the air in fish helps to elude predatory pursuers. But in reality, it turns out that the fish is above the surface of the water, where birds are waiting for it, which also feed on fish. These include gulls, albatrosses, frigates, sea eagles, kites. These celestial predators, even from a height, possess above the surface of the water, track down shoals and flocks. At the right moment, they abruptly fall down for prey. The fish, which has gained speed, flies to the surface and falls directly into the paws. Man also mastered this method. In many countries, fish are caught on the fly, hanging nets and nets above the surface.
However, under water, flying fish have more enemies. For example, tuna, common in warm waters, lives side by side with flying fish and feeds on it. It also serves as food for such fish as bonito, bluefish, cod and some others. Flying fish are attacked by dolphins and squids. Sometimes it becomes the prey of sharks and whales, which do not hunt such small fish, but are happy to eat it along with plankton if they accidentally hit it.
Population and species status
The total biomass of flying fish in the World Ocean is 50-60 million tons. The fish population is quite stable and numerous, therefore, in many countries, for example, in Japan, its species have the status of commercial fish. In the tropical Pacific Ocean, the stock of flying fish is between 20 and 40 kilograms per square kilometer. About 70 thousand tons of fish are caught annually, which does not lead to its reduction, since without a reduction in the average annual number, the possible withdrawal of mature individuals can reach 50-60%. What is not happening at the moment.
There are three main geographical groupings of flying fish that inhabit the Indo-West Pacific, East Pacific and Atlantic faunal regions. More than forty individual species of flying fish live in the Indian Ocean and the Western Pacific. These are the most inhabited by flying fish waters. In the Atlantic, as well as in the east of the Pacific Ocean, there are fewer of them — about twenty species each.
Today, 52 species are known. The flying fish species is divided into eight genera and five subfamilies. Most individual species are distributed allopatrically, that is, their habitats do not overlap, and this allows them to avoid interspecific competition.