One of the breeding features of sharks that distinguishes them from bony fish, is internal fertilization. The male fertilizes the egg directly in the body of the female, introducing the genital organs - pterygopodia into her cloaca. Pterygopodia are modified rays of the ventral fins of the male shark. Females do not have such organs. The further process of the birth of offspring in sharks proceeds according to three different scenarios, the description of which is given below.

Oviposition.

Oviparous sharks lay eggs that are structurally similar to those of birds or reptiles. They have only an external difference - shark eggs do not have the usual oval or round shape - they are covered with various outgrowths, antennae or growths, and their shape is often intricate.
However, these are the most common eggs, from which fry of sharks hatch over time. Like other egg-laying animals, shark eggs contain many nutrients that allow the embryo to develop successfully.
The process of incubation of eggs is quite long, sometimes more than a year. A baby shark hatched from an egg is capable of independent living.

The shell on the eggs of sharks is formed during the passage through the female's oviduct through the protein and shell glands. The horny coating of shark eggs protects them from mechanical damage, dehydration and, in some cases, allows them to hang eggs on algae using special antennae and outgrowths.
Sometimes the sea throws shark eggs ashore, and they lie on the sand like bizarre sea creatures. AT old times people called such finds "mermaid purses", not finding a correct explanation for the appearance of these strange objects.

Many species of bottom sharks breed by oviposition; among the free-swimming ones, one can note the polar (Greenland, ice) shark, which lays up to 500 eggs, resembling goose in shape and size. The usual clutch of most egg-laying sharks does not exceed one and a half dozen eggs.
Oviposition breeds about 30% known species sharks

Ovoviviparity.

Reproduction of sharks by ovoviviparity - unique way, inherent only in cartilaginous fish. Why nature invented such an unusual way of reproducing offspring, scientists still cannot explain. Perhaps this is a dead end branch of one of the many evolutionary experiments.

Oviparous differs from oviposition only in that the fertilized and formed eggs do not leave the body of the female, but remain in a special section of the oviduct, called the uterus, until the fry hatch. The mother's body in this case is a kind of incubator in which the eggs can develop in relative warmth (if you can use this term for fish) and safety.
This method of reproduction differs from true live birth in that the embryos receive nutrients not directly from the mother through a special connecting "channel" - the placenta, but have a supply of nutrition in their egg capsule, which is enough for the entire period of intrauterine development.
Most reproduce by ovoviviparous modern species sharks Among them are sharks such as katran, giant, giving birth to 1-2 cubs every two years, tiger, bringing up to 50 babies in one litter. Cubs are born well developed and able to exist independently.
You can watch a short video about how the birth of an ovoviviparous shark takes place on this page.

For ovoviviparity of sharks, such a phenomenon as intrauterine cannibalism is characteristic, when sharks that have hatched earlier from eggs eat their brothers and sisters, who were late with hatching, right in the womb.

Live birth.

During a live birth, an embryo develops in the body of the female, which receives nutrients directly from the mother's body, by analogy with mammals.
The connection of the embryo with the body of the female is not carried out immediately - for some time (sometimes up to several months), the embryo feeds on the supply of substances that are in the yolk sac of a fertilized egg. Then the yolk sac is transformed into the placenta, which serves to connect the embryo with the mother's body.
It cannot be said that the most modern of the shark species reproduce in this way, since live birth is inherent, for example, in the most ancient shark - the frilled shark. A tenth of the known species of sharks reproduce by live birth, including all types of gray sharks, some hammerheads.

Among interesting features shark breeding should be noted such a phenomenon as asexual reproduction or parthenogenesis. In some oceanariums, cases of reproduction of offspring by female sharks were noted, which were kept without males for a long time, i.e. the fact of fertilization was excluded. According to scientists, this is a kind of protective function that protects the shark species from extinction.

One of ancient species animals, mysterious and little studied - these are sharks, or, as they are also called, selachia. Many myths and legends surround this representative of the marine fauna and form a prejudice against amazing fish. The systematic study of selachium began during the Second World War, during the battles in the basins of the Pacific and Indian Oceans. The task was to find a means of protecting people from attackers. marine predators.

Is a shark a fish or a mammal

The list of these marine predators includes more than 400 species, polarly different: from the smallest deep-sea, barely growing to 17-20 cm, to the giant - whale shark, a huge 20-meter multi-ton individual.

The name "mammal" speaks for itself. Those animals that feed their young with milk are called "mammals".

The shark does not feed its cubs with milk, in addition, the shark breathes with the help of such a device - “gills”. Shark is a fish.

In size, of course, these predators are comparable to dolphins or some types of whales. But in the maritime kingdom there are many similar in size, but different in content.

AT modern classification The animal kingdoms sharks and rays form a subclass of Sharks, which belongs to the class Cartilaginous fish. Cartilaginous fishes, mammals, and also humans form a single type according to a number of similar features - Vertebrates.

Skeleton bony fish composed entirely of bones, in sharks there are only cartilage. A large amount of calcium makes cartilage hard and strong. A curved, impressive mouth is placed on the lower part of the head.

The large and soft caudal fin is asymmetrical - the upper lobe is much larger than the lower one. Bony fish move their lateral fins freely, unlike selachians.

Bony fish and shark, what are the similarities and differences

Mammals and a shark, what are the differences

One of unique properties electroreception, the ability to sense electrical and magnetic signals environment. Used to detect prey, orientation in space, to maintain contact with their relatives.

Electroreceptor sensory organs are present both in selachia and stingrays, and in some species of bony fish. Of the mammals, the Australian platypus and, presumably, the echidna can boast of having electroreceptors. Ampoules of Lorenzini - so called electroreceptor apparatus predator, which she successfully uses at the time of the attack.

In the process of evolution, the relief of the Earth changed - oceans arose in place of the land or, conversely, the continents went under the water column. Some forms of life disappeared, others appeared. Only the selachians continued to exist for almost 500 million years. Some representatives of this unique and little-studied species have not changed much.

The largest copy fossil carchadon, the ancestor of the great white shark. Its size was restored from the fossilized teeth found, the size of which is 10–15 cm. It is believed that seven people could fit in its mouth. The smallest living member of the species is dwarf glowing shark only 7 cm long.

One of the breeding features of sharks, which distinguishes them from bony fish, is internal fertilization. The male fertilizes the egg directly in the body of the female, introducing the genital organs - pterygopodia into her cloaca. Pterygopodia are modified rays of the ventral fins of the male shark. Females do not have such organs. The further process of the birth of offspring in sharks proceeds according to three different scenarios, the description of which is given below.

Oviposition.

The shell on the eggs of sharks is formed during the passage through the female's oviduct through the protein and shell glands. The horny coating of shark eggs protects them from mechanical damage, dehydration and, in some cases, allows them to hang eggs on algae using special antennae and outgrowths.
Sometimes the sea throws shark eggs ashore, and they lie on the sand like bizarre sea creatures. In ancient times, people called such finds "mermaid purses", not finding a correct explanation for the appearance of these strange objects.

Ovoviviparity.

Reproduction of sharks by ovoviviparity is a unique method inherent only in cartilaginous fish. Why nature invented such an unusual way of reproducing offspring, scientists still cannot explain. Perhaps this is a dead end branch of one of the many evolutionary experiments.

Oviparous differs from oviposition only in that the fertilized and formed eggs do not leave the body of the female, but remain in a special section of the oviduct, called the uterus, until the fry hatch. The mother's body in this case is a kind of incubator in which the eggs can develop in relative warmth (if you can use this term for fish) and safety.
This method of reproduction differs from a real live birth in that the embryos do not receive nutrients directly from the mother through a special connecting "channel" - the placenta, but have a supply of nutrition in their egg capsule, which is enough for the entire period of intrauterine development.
Most modern shark species reproduce by ovoviviparity. Among them are sharks such as katran, giant, giving birth to 1-2 cubs every two years, tiger, bringing up to 50 babies in one litter. Cubs are born well developed and able to exist independently.
You can watch a short video about how the birth of an ovoviviparous shark takes place on this page.

Live birth.

Among the interesting features of shark breeding, one should note such a phenomenon as asexual reproduction or parthenogenesis. In some oceanariums, cases of reproduction of offspring by female sharks were noted, which were kept without males for a long time, i.e. the fact of fertilization was excluded. According to scientists, this is a kind of protective function that protects the shark species from extinction.

Representatives of the shark superorder reproduce offspring in several ways, depending on their biological species. characteristic feature Shark breeding is internal fertilization.

In this they differ from most other fish. To do this, males have a special genital organ - pterygopodia. Juveniles may be born from eggs or by ovoviviparity. Also, some varieties have a real live birth.

Shark breeding and egg-laying

About a third of all these marine predators reproduce by eggs or capsules. They are covered on top with a dense horny shell, unlike birds, they may not have a rounded, but an intricate shape. They may have outgrowths or antennae, with the help of which they linger on the bottom among algae or stones.

The capsules contain a large number of nutrients, due to which the embryo grows and develops. The incubation period can be long, sometimes it lasts more than a year. After its completion, a fully formed fry is born, which is able to get food like an adult animal.

This is how most bottom varieties reproduce, which lay no more than 15 eggs at a time. Of the free-swimming species, a polar variety is known, which lays up to 500 capsules.

Shark breeding: ovoviviparity

This method differs from true live birth in that the fertilized eggs remain to develop in the body of the female. When the fry are already sufficiently formed and developed, the female gives birth to formed live fry. But juveniles receive nutrients not from the mother's body, but from the capsule in which they are located.

Oviparous allows you to save offspring much more efficiently than with oviposition. The deposited capsules can become easy prey for predators, but when they are in the body of the female, they are reliably protected during their development.

Also in these animals, cases of parthenogenesis or asexual reproduction have been recorded. In the absence of a male, the female is sometimes able to reproduce offspring without fertilization.

This amazing feature allows these inhabitants of the sea to give birth in any conditions, and protects these fish from extinction.

Very many species reproduce by ovoviviparity, for example, tiger and katran, which bring up to 50 fry in a litter.

Embryos of the cat shark

True live birth

This method is similar to mammalian reproduction when the embryo is in special body- the uterus, and with the mother's body is connected with the help of the placenta. The placenta appears over time. Up to this point, the embryo develops due to its yolk sac.

Reproduction of sharks, in which live cubs are born, is considered the most progressive way. This method is found only in cartilaginous fish and is not characteristic of bones.

Australian bull shark with egg

Such a reproduction of their own kind is observed not only in the most modern species, but is also found in the most ancient ones. About one tenth of all these oceanic predators living today reproduce in this way.

Live birth as a way of reproduction of sharks is a progressive step on the evolutionary path of these species. In this case, already fully formed cubs appear, the survival rate of which is much higher than that of larvae emerging from eggs.

Therefore, if spawning fish can lay several hundred eggs, of which only a few survive to adulthood, then it is enough for viviparous fish to give birth to several cubs to ensure the survival of the species.

Newborn baby shark

About sharks, ancient sea creatures, you can talk for a very long time. And we will continue this conversation on the pages of new articles:

When asked WHO knows how sharks reproduce. given by the author compound the best answer is There are three main methods of shark reproduction: live birth, ovoviviparity (the embryo develops in an egg in the mother's body) and oviposition (the embryo develops in an egg laid in water). Despite different ways All sharks are characterized by internal fertilization. To provide it, the inner edge of each ventral fin of males is turned into a tubular appendage - pterygopodia. During reproduction, one of the pterygopodia bends forward and is introduced into the female's cloaca.
In oviparous species, the fertilized egg, descending the oviduct, passes through the protein and shell glands, thanks to which it acquires a hard shell. The egg is then laid on the bottom. The only exception is the eggs of the polar shark, which do not have a hard shell. Such a great fecundity of this species of sharks is associated with its absence. The fact is that unprotected eggs are a great delicacy for many bottom-dwelling predators, so in order to preserve the species, the shark must lay much more eggs. During the autopsy of the polar shark, several thousand eggs were found, with a total weight of 134 kilograms. All other egg-laying sharks lay no more than 10 pieces.
Most modern sharks are ovoviviparous and are characterized by the fact that the fertilized egg remains in the posterior part of the oviducts (in the "womb") until the birth of juveniles. In addition, a number of sharks have oviparous larvae and cannibals. After hatching, egg-eating larvae remain in the uterus for some time and feed on unfertilized eggs, constantly formed by the female. Cannibals are usually the first and largest larvae to hatch there, devouring both unfertilized eggs and their fellows. In ovoviviparous sharks, juveniles are born fully formed. This group includes, for example, giant shark, which every two years brings 1-2 offspring 1.5-2 meters each.
In viviparous sharks, the development of the embryo also occurs in the "womb", in which there is even a semblance of a child's place (placenta), which serves to nourish the embryo at the expense of maternal blood. The number of newborn sharks in viviparous sharks is relatively small: from 2–4 in sea fox up to 4–5 in the blue shark. Newborn sharks already have a length of 1-1.5 meters and are completely ready for independent existence.
Source:

Answer from I-beam[guru]
viviparous in my opinion

Answer from Natasha[guru]
The shark, like all cartilaginous fish, has internal fertilization. The copulatory organ of males is a pair of pterygopodia, each of which is a modified rear part of the ventral fin. During reproduction, one of the pterygopodia bends forward and is introduced into the female's cloaca. The fecundity of sharks is low, but their eggs have significant nutrient reserves.
Sharks are divided into oviparous, ovoviviparous and viviparous.
In oviparous species, a fertilized egg, descending through the oviduct, passes through the protein and shell glands, and is dressed in shells that form a hard, often covered with outgrowths, shell. In ovoviviparous, which include most modern sharks, egg development and hatching of juveniles occur inside the lower expanded part of the oviduct, usually called the uterus. Finally, during a live birth (for example, in a gray-blue shark or an American long-finned shark), the embryo, also developing in the "womb", first feeds on yolk reserves, and later, through the placenta formed, receives the substances necessary for development directly from the maternal bloodstream. There are intermediate options between ovoviviparity and live birth.
In addition, a number of sharks have egg-eating larvae, which, after hatching, remain in the uterus for some time and feed on unfertilized eggs constantly formed by the female.

Answer from Complete happiness)))[guru]
viviparous like whales and dolphins

Answer from reroll[guru]
I know that they do not lay eggs like other fish. But I bear sharks

Answer from Irina Lopatnikova[guru]
Like all fish, they spawn

Answer from Butterfly[guru]
Sharks are viviparous...

Answer from Black Cat[guru]
The way sharks reproduce gives them some advantages over other species. A newborn is born fully prepared for an independent life, he already knows how to avoid the dangers that await him at every turn, and these can be adult sharks, and even his own mother. There are viviparous sharks that breed like mammals; there are - ovoviviparous, that is, the egg develops in the mother's womb, the cub hatches there and only then comes out into the light of day. Very few species are oviparous: the female lays an egg, and this is where her parental mission ends. Female sharks can breed without the participation of males. This sensational conclusion was reached by Irish and American scientists who studied these fish in captivity, reports The Sun. Specialists from Queen`s University in Belfast and Nova Southeastern University in Florida, together with the Henry Doorly Zoo in Nebraska, found that sharks can breed asexually through parthenogenesis. This is the first scientific evidence of this ability in sharks. Dr. Paulo Prodol from Queen`s University says: “The results were really amazing, because as far as we knew, all sharks only sexual reproduction, and the embryo requires the DNA of both parents for full development like all mammals. Now, after this discovery, mammals are the only major group of vertebrates where this form of reproduction does not occur.