Dog fishes: representatives, examples, photos
Lungfish were found only in the pastcentury. Until that moment no one saw them live. Representations about them were limited only to found ancient remains. Their structural features determined such an interesting name. Let's figure out what kind of fish is double-digging and what's so special about it. The point is that representatives of this class can breathe not only gills, but also lungs.
Who are the lungfish?
Representatives of this order of lobe-hopper fishhave simultaneous gill and pulmonary respiration. This is the peculiarity of their structure. In the modern world, a subclass of lungfish, whose representatives are divided into two orders - corneous and two-leaved, is rare. Related individuals live only in Africa, Australia and South America.
In addition to the usual gills, they also have lungs (oneor two), which are a modified swim bladder. Through its walls, permeated with capillaries, actually, and there is a gas exchange. Fish capture the air for breathing with their mouths, rising to the surface. In the atrium they have a septum, which continues in the ventricle. Blood through the veins comes from the organs and enters the right side of the atrium, as well as the right half of the ventricle. The blood that comes from the lung enters the left side of the heart. An interesting fact is that further oxygenated pulmonary blood goes mainly to those vessels that pass through the gills to the head and various organs. And the second part of it from the right side of the heart, also passing through the gills, appears in a vessel leading to the lung. It turns out that rich in oxygen and poor blood still partially mixed in blood vessels and heart. So, we can talk about primitive rudiments of two circles of blood circulation in lungfish.
Dog fishes are representatives of a very ancientgroup. Their remains are found among the deposits of the Devonian period (Paleozoic era). For a long time such fish were known only for petrified remains. And in 1835 it was discovered that the protopter that inhabits Africa is a double-boiled fish.
The subclass of the lungfish, whose representatives have survived to this day, consists of only six species:
- Australian shaggy - a detachment of one-pulmonary.
- American scaly from a two-legged squad.
- Four species of Protopterus from Africa (two-pulmonary).
Apparently, they all together with their ancestors are related to freshwater fish.
Double-digging fishes include Australianrogodocks. They occur on a very small area of the basin of the Mary and Bernett rivers in the north-east of Australia. This is a large fish up to 175 centimeters long, and weighing more than ten kilograms.
The large body of the dagger is flattened on the sides andcovered with large scales. Large paired fins look like fins. The color of the body of the corpuscle varies from reddish-brown to bluish-gray in color, and the belly is necessarily of a light shade.
Inhabits fish in rivers with a slow current, there,where there are surface and underwater thickets. Every fifty minutes the corpuscle rises to the surface and blows air from the lungs with a noise. At the same time he makes out a groan, or a grunt, which is heard far enough. Breathing in fresh air, the fish again sinks to the bottom.
The habitat of the rosemal
Rogozub mainly spends time on the bottom, lying onbelly or standing on the flippers. To search for food, he begins to slowly creep. The fish are swimming too extremely slowly. However, if it is scared, then it begins to work quickly with its tail, thus accelerating its movement.
In periods of drought, when the rivers are becoming shallow,Rogozub lie in the remaining pits with water. In hot water, devoid of oxygen, all the fish die, and she turns into a stinky, dirty scum. In such conditions, only lungfish survive, whose representatives are able to breathe lungs. However, if the water evaporates completely, then the cuckolds still die, because, unlike the South American and African relatives, they do not know how to go into hibernation.
Spawning in fish falls during the rainy season, when riversoverflowing with water. Large eggs rogodooth lays on algae. After 12 days, larvae appear which are at the bottom until the yolk sac dissolves, sometimes moving slightly for insignificant distances.
It is believed that on day 14 after the appearance of the frylight begins to function in them. Rogozuby very tasty, and catch them very simply. This led to a sharp reduction in their numbers. Currently they are under protection, in addition, attempts are being made to move them to other Australian ponds.
Protopters - African lungfeeding
To doubly breathing fishes belong and protopters. They live in Africa and have filiform fins. Of the four species living on the continent, the largest - a large protopter - reaches a length of more than a half meters. The average length of the fish is about thirty centimeters. Fish swim like eels, wriggling the body. But threadlike fins move along the bottom. Interesting is the fact that the fin skin is rich in receptors. As soon as the fin touches something edible, the fish immediately grabs its prey. Periodically, the protopter floats up and inhales fresh air. Protopters live in the central regions of Africa. What are the two lungs for life? Representatives of this species prefer rivers and lakes in swampy terrain, which are annually flooded during rains and dry out during a drought. In the dry period, the water level drops from five to ten centimeters. At this time the protopters begin to dig holes for themselves.
The fish absorbs the soil with the mouth and then grinds itand throws it out through the gills. Nora is a vertical path, at the end of which there is a camera, where, in fact, the protopter is located, bent in half and with its head exposed.
Until the water is completely dry, fishrises to breathe. And then the liquid sludge is sucked into the hole, blocking the outlet. Then the protopter can not get out. He just pokes his snout in a cork of silt, lifting it. After drying, it becomes porous and lets in oxygen, which makes it possible for fish to survive in hibernation.
The water in the hole gradually becomes very viscousbecause of the mucus secreted by the protopter. The soil gradually dries more and the water level in the hole drops. As a result, the vertical stroke is filled with air. Bending over, the fish freezes in the lower chamber. A cocoon of mucus forms around her body. It is in this condition that the protopter expects a rainy period, which occurs only after 6 to 9 months.
Fish behavior during the dry season
Are sufficiently interesting in their behavior and conditionsinhalation of lungfish. Representatives (the photos are shown in the article) of this group participated in laboratory studies. So, the protopters were kept in hibernation for more than four years, and at the end of the research they were safely awake.
During the period of hibernation, fish exchangeprocesses. Nevertheless, in six months the protopters lose up to 20 percent of their mass. Energy enters the body due to the breakdown of muscle tissue, so ammonia accumulates in the body. In the active period of the existence of fish, it calmly goes outside, but during hibernation it turns into a very toxic urea, the concentration of which is quite high. But the poisoning of the body does not occur. How does such stability arise, has not yet been clarified.
With the onset of the rainy season, a gradualsoaking up the soil, water fills the hole, protopter, breaking the cocoon, periodically pops out his head and inhales air. Once the water has completely covered the bottom of the pond, the fish will leave the hole. In a month and a half, the prototypes will begin the breeding season. At this time, the male digs a new norm in the thickets and lures the female there, which will postpone up to 5 thousand eggs. And in 7 days there will be larvae. And after 4 weeks the fry begin to eat independently and leave the mink. Still some time they float near to it, hiding at the slightest danger. All this time the male is always near the hole and protects it from enemies.
Considering the theme "Lungfish: representatives, names ", it is necessary to recall one more representative of this class - a dark protopter. It lives in the basin of the Congo and Ogooue rivers, preferring wetlands where the underground water level persists even during a drought. When the water begins to decrease in the river, the fish burrows into the bottom silt, reaching the underground water. There, the protopter spends the entire dry period, without creating a cocoon, periodically it rises to the surface to breathe in air.
The burrow of the fish is an inclined course andcamera at the end. Fishermen say that such a refuge serves the protopter five to ten years. In the same hole, spawning takes place. The males prepare for this event in advance, increasing around the hill from the mud, which can reach one meter in height.
Lungfish, briefly described by us inarticle, always attracted the attention of scientists, so they are unusual and interesting. Protopters interested researchers of sleeping pills. The biochemists of Sweden and England tried to isolate substances from the organisms of fish, which enable them to hibernate. And that's interesting: when the extract from the brain of sleeping fish was injected into the blood of laboratory rats, the body temperature of the subjects began to drop sharply, they fell asleep very quickly, almost instantaneously. The dream lasted until 18 hours. After awakening, rats failed to detect any sign of artificial sleep. The substance did not give any side reactions.
American scaly, or lepidosiren
The examples of lungfishdemonstrate their adaptability to completely unfit for living conditions. And, nevertheless, even in such circumstances, thanks to the ability to breathe in two ways, the fish feel great.
In the class of the lungfish, representativeswhich was discussed above, includes the American scaly cat that lives in the Amazon basin. The length of the fish reaches 1.2 meters. It lives, as a rule, in temporary reservoirs, which floods in the period of rains or spills. Feed on flakes of various animal food, mainly mollusks. Perhaps they also eat vegetarian food. When the reservoir drains, the fish lie on the bottom of the burrow and are clogged with a stopper. However, they do not form cocoons. The sleeping fish is surrounded by mucus and moistened by groundwater. The basis of energy metabolism, unlike the protopter, is stored fat.
A couple of weeks after flooding the pondthe American scaly cat begins to multiply. The male digs out a burrow that can be up to a meter and a half in length. In its very depths, he drags grass and leaves onto which females are rushing eggs. The male remains in the burrow and protects the young. During this period, he has accretions on the ventral fins. Some ichthyologists say that these are temporary external gills for additional breathing. Others believe that with the help of these outgrowths the fish give off some oxygen, taken during the rise to the surface of the reservoir. True or not, it is not known. However, after the breeding period, the outgrowths disappear.
Dog firing. Representatives: coelacanth
Another representative of lungfishare coelacanth (tselakanty). They are very few and covered with a mysterious veil. They live near the Comoros. However, local fishermen have extracted them for the whole history of not more than two hundred pieces. The length of the fish is from 43 to 180 centimeters, and the weight reaches 95 kg. Interesting is the fact that all the coelacanths were caught from September to April, and in the dark. Fishermen caught them for bait from squid or slices of fish. Fishing rods were thrown at decent depths (from 150 to 400 meters). Attempts were made to catch the latimerium with traps or a trawl, but none of this came to pass. Perhaps the fault is the difficult terrain of the fish habitat.
The coelacanth is a double-digging fish. It has a rather interesting structure. For example, she does not have vertebrae. The spine is formed by an elastic thick stem. The swim bladder, which is easy for the lungfish, is shortened to a small tube. The eyes of the coelacanth are adapted to dwelling in the dark. Biology of coelacanth has been studied very little. Generally speaking, they are very interesting in terms of their habitat, lungfish. Representatives (their list was given by us in the article) of this class is quite unique. There are not so many on the ground. Moreover, because of good taste qualities, they are still subject to extermination.
But as for the coelacanth, it is notSo it's easy. Scientists suggest that it lives among the basaltic rocks of Comoros rocks at great depths. Those rare specimens that caught the fishing line, of course, were subjected to a close inspection. So, in their stomachs were found the remains of deep-sea fish, living at a depth of 500 to 1,000 meters. Most likely, the coelacanth has a sedentary life, although, as we have already said about lungfish, they can make sharp throws due to their strong tail. Movable paired fins help them to squeeze into clefts of rocks. The coelacanth does not tolerate bright sunlight and high temperature of the surface layers of water.
The last representative of the brush blood on the earth
In fact, coelacanth is the only type of tselakantovyh fish, preserved to this day. Their detection is comparable only with the discovery of a living dinosaur.
Of course, coelacanth is very different fromtheir ancient predecessors, who once inhabited shallow waters of the coastal zone and fresh water bodies. Such conclusions were made by scientists on the basis of found fossils. By the way, with the help of the same fossils, experts have concluded that the ancient Celakantians lived 400 million years ago, and therefore, even before the advent of dinosaurs.
Latimeriya - the only representative on earthcystoper fish. Its discovery was the largest discovery in the zoological area in the twentieth century. It happened in 1938. Fishermen in the Indian Ocean caught a very large unknown fish with quite aggressive behavior. Her study and led to a terrific discovery - that this is the last representative of brush-blooded fishes on the ground, which were formerly considered long-extinct.
The habitation of the coelacanth was established for years.Gradually found out that she lives about three Comoros, as well as off the coast of southern Mozambique and the south-western coast of Madagascar. And in 1998, a fish population was found near the Indonesian coast.
Currently, scientists talk about two typesLatimerians - Indonesian and Camorian. How many fish are found near the coast of Indonesia, is unknown, but the Comoro Islands are home to about two hundred individuals. All the tselakanty are under close monitoring. The catch of this fish is strictly prohibited.