Because every being endowed with the respiratory organs, we all get something without which we can not live - oxygen.All land animals and humans, these bodies may be small, that absorb the maximum amount of oxygen from the air.The respiratory system is made up of the fish gills, which are drawn into the body oxygen from the water, where it is much less than in the air.It is because of the structure of the body of this species is so different from all the terrestrial vertebrates beings.Well, look at all the structural features of the fish, their respiratory system and other vital organs.
briefly about fish
To start with try to understand what kind of creatures are and how they live, what are the relationship with the person.For now, we start our biology lesson, the topic of "Marine fish".This superclass vertebrate animals that live exclusively in an aqueous medium.A characteristic feature is that all the fish chelyustorotnye and have gills.Worth noting that these figures are characteristic of each type of fish, irrespective of size and weight.In this subclass of human life plays an important role economically, since most of its representatives are eaten.
It is also believed that the fish were at the dawn of evolution.These are the creatures that might dwell under water, but did not yet have jaws that once were the only inhabitants of the Earth.Since species evolved, some have turned to animals, some were under water.That's the whole biology lesson.The theme of "Marine fish. A Brief History" is considered.The science that studies the marine fish is called "ichthyology".Let's now move on to study these creatures with a more professional point of view.
general scheme of the structure of fish
generalizations can be said that the body of each fish is divided into three parts - head, torso and tail.The head ends in the area of the gills (in their beginning or end - depending on the superclass).The trunk line terminates at the anus at all representatives of this class of marine life.The tail is the same - the simplest part of the body, which consists of a rod and fin.
shape of the body is strongly dependent on environmental conditions.Fish that live in the water column average (salmon, shark) has a torpedo shape, at least - arrow-.Those sea creatures that float above the bottom, have a flattened shape.These include flounder, foxes and other marine fish are forced to swim among the plants or rocks.They become more agile shape, which have much in common with snakes.For example, acne is the owner of a strongly elongated body.
Card fish - its fins
without fins is impossible to imagine the structure of the fish.Pictures that are presented in children's books, be sure to show us the body of marine inhabitants.What are they?
So fins are paired and unpaired.The guy may include abdominal and chest, which are symmetrical and synchronized moves.Unpaired represented as the tail, the dorsal fin (one to three), as well as the anal and fat, which is located immediately behind the dorsal fin.Fins themselves are composed of hard and soft radiation.It is based on the number of fin rays calculated formula that is used to identify a specific type of fish.Latin letters is determined by the location of the fin (A - Anal, P - the chest, V - abdominal).Next Roman numerals indicate the number of hard rays, and Arabic - soft.
Classification fish
today suspended all fish can be divided into two categories - the cartilage and bone.The first group includes such inhabitants of the sea, which consists of a skeleton of cartilage of different sizes.This does not mean that such a gentle creature and mobility.Many representatives of the superclass cartilage hardens, and its density becomes almost like a bone.The second category - bony fish.Biology as science says that this is the superclass was the starting point of evolution.Once within it was extinct Crossopterygii fish, from which, perhaps, there were all terrestrial mammals.Next, we consider in more detail the structure of the fish of each of these species.
Cartilage
In principle, the structure of cartilaginous fish is a not something difficult and unusual.This is a normal skeleton, which consists of a very hard and durable cartilage.Each compound is impregnated with calcium salts, which in the cartilage and there is strength.Chord keeps its shape throughout life, while it is partially reduced.The skull is connected to the jaws so that the fish skeleton has a complete structure.To him also attached fins - the tail, paired abdominal and chest.The jaws are located on the ventral side of the skeleton, and above them are two nostrils.Cartilaginous skeleton and muscular system of fish from the outside is covered with thick scales, called placoid.It consists of dentin, which in its composition is similar to ordinary teeth of land mammals.
As cartilage breathe
Respiratory superclass cartilaginous fishes presented first gill slits.They account for 5 to 7 pairs on the body.In the internal organs of oxygen distributed through the spiral valve which stretches along the entire body of the fish.A characteristic feature of all the cartilage is that they do not have a swim bladder.That is why they have to be constantly on the move, not to go to the bottom.It is also important to note that the body of cartilaginous fish that inhabit priori saline waters contained a minimum quantity of the salt itself.Scientists believe that this is due to the fact that in the blood of the superclass lot urea, which consists essentially of nitrogen.
Bone
Now consider what it looks like the skeleton of a fish belonging to the superclass of bone, as well as find out what else is characterized by representatives of this category.
So skeleton represented as the head, torso (they are separate, unlike in the previous case), as well as paired and unpaired extremities.Skull is divided into two sections - the cerebral and visceral.The second involves the jaw and the hyoid arch, which are the main components of the jaw apparatus.Also in the skeleton bone fish are gill arches which are intended to hold the gill apparatus.With regard to the muscle of the fish species, they all have a segmental structure, and the most advanced of them - it's jaw, fin and gill.
breathing apparatus bony sea creatures
Perhaps it became clear to everyone that the respiratory system of fish superclass bone mainly consists of gills.They are located on the gill arches.It is also an integral component part of such fish are gill slits.They are covered with a cover of the same name, which is intended to fish could breath in immobilized state (as opposed to cartilage).Some members of the superclass bone can breathe through the skin.But those that inhabit directly beneath the water surface, and thus never deeply sink, on the contrary, their gills capture air from the atmosphere, rather than from an aqueous medium.
structure
gills Gills - a unique body that was previously common to all protoaquatic creatures living on Earth.It is the process of gas exchange between the body and gidrosredoy in which they operate.The gills of fish of our time are not much different from those of the gills, which were inherent in the earlier inhabitants of our planet.
As a rule, they are presented in the form of two identical plates, which are imbued with a very dense network of blood vessels.An integral part of the gills is coelomic fluid.That it makes the process of gas exchange between the aqueous medium and the body of the fish.Note that the description of the respiratory system of not only fish, but many vertebrates and vertebrate inhabitants of the seas and oceans.But what is special about yourself are exactly the respiratory system that are in fish, read on.
Where are the gills
respiratory system of fish are mostly concentrated in the throat.It was there that are located gill arches, which are attached with the same name on the bodies of gas exchange.They are presented in the form of petals, which is passed through it and the air, and a variety of life-saving fluids that are inside each fish.In certain places sip threaded gill slits.It is through them the oxygen that enters the mouth of the fish to swallow it with water.
A very important fact is that in comparison with the size of the body of many marine species, their gills are very high for them.In this regard, in their bodies have problems with the osmolarity of blood plasma.Because of this, the fish are always drinking sea water and release it through gill slits, thus speeding up various metabolic processes.It has a smaller consistency than the blood, for quickly and efficiently provides the gills and other internal organs with oxygen.
The process of breathing
When the fish only is born, breathes almost all her body.Blood vessels permeated each of its body including an outer shell, because oxygen, which is in sea water penetrates into the body permanently.Over time, each such individual begins to develop gill respiration, as the largest net of blood vessels is equipped with gills and all adjacent organs.Then the fun begins.The process of respiration of each fish depends on its anatomical features, because in ichthyology be divided into two categories - active and passive breathing.If the active understanding (fish is breathing "normally", picking up oxygen in the gills and treating it like a man), the passive we are try to understand in more detail.
Passive breathing and what it depends
This type of breathing is characteristic only of high-speed inhabitants of seas and oceans.As we mentioned above, the shark, as well as some other members of the superclass of the cartilage can not be a long time without moving, as they have no swim bladder.It has another reason - namely, this is passive breathing.When a fish swims at high speed, she opens her mouth, and automatically goes to the water.Approaching the trachea and the gills, oxygen is separated from the liquid, which nourishes the body skorohodnymi sea dweller.That is why for a long time without moving the fish being deprived of the chance to breathe, without spending any effort and energy.Finally, we note that such high-speed inhabitants are mostly salt water shark and mackerel all members.
main muscle of the body fish
very simple structure of the heart is the fish, which we note in the history of this class of animals, hardly evolved.So this body have double chamber.He is represented by one main pump, which includes two chambers - atrium and ventricle.Fishy heart pumps venous blood only.In principle, the circulatory system in this species of marine life is a closed system.Blood circulates through kapilyarchiki gills and then is discharged into the blood vessels, and then again diverge into smaller capillaries, which are already provided with other internal organs.After this "work" the blood is collected in the veins (they have two fish - liver and cardiac), from which goes directly to the heart.
Conclusion
That came to an end our brief lesson in biology.Thread the fish turned out to be very interesting, fun and easy.The body of data of marine life is extremely important for the study, as it is believed that they were the first inhabitants of our planet, all of them - this is the clue to evolution.Furthermore, to study the structure and operation of the fish body is much simpler than any other.And the size of these inhabitants of the water Stoch is acceptable for a detailed review, and with all the education system and are simple and easy even for children of school age.
