Who grows out of a tadpole. Frog developmental stages. Birth of poison dart frogs

Frogs, gametogenesis, fertilization and other seasonal events depend on numerous external factors. The life of almost all amphibians depends on the number of plants and insects in the pond, as well as the air and water temperature. Different stages of development of frogs are distinguished, including the larval stage (egg - embryo - tadpole - frog). The metamorphosis of a tadpole into an adult is one of the most striking transformations in biology, as these changes prepare an aquatic organism for terrestrial existence.

Development of frogs: photo

In tailless amphibians, such as frogs and toads, metamorphic changes are most pronounced, almost every organ undergoes modification. The shape of the body changes beyond recognition. After the appearance of the hind and forelimbs, the tail gradually disappears. The cartilaginous skull of the tadpole is replaced by the facial skull of the young frog. The horny teeth that the tadpole used to eat pond plants disappear, the mouth and jaws take on a new shape, the muscles of the tongue develop more strongly to make it easier to catch flies and other insects. The elongated large intestine characteristic of herbivores shortens to accommodate the adult's carnivorous diet. At a certain stage in the development of frogs, the gills disappear, and the lungs increase.

What happens immediately after fertilization?

Soon after, it begins to move from one cell stage to another in the process of division. The first cleavage starts at the animal pole and runs vertically down to the vegetative pole, dividing the egg into two blastomeres. The second cleavage occurs at right angles to the first, dividing the egg into 4 blastomeres. The third furrow is at right angles to the first two, being closer to the animal than to the vegetative pole. It separates the top four small pigmented areas from the bottom four. At this stage, the embryo already has 8 blastomeres.

Further splits become less regular. As a result, a unicellular egg gradually turns into a unicellular embryo, which at this stage is called a blastula, which, at the stage of 8-16 cells, begins to acquire spatial cavities filled with liquid. After a series of changes, a single-layer blastula turns into a two-layer embryo (gastrula). This complex process is called gastrulation. The intermediate stages of frog development at this stage involve the formation of three protective layers: ectoderm, mesoderm and endoderm, which are also known as primary. Later, larvae hatch from these three layers.

Tadpoles (larval stage)

The next after the embryo is the larva, which leaves the protective shell already 2 weeks after fertilization. After the so-called release, the frog larvae are called tadpoles, which are more like small fish about 5-7 mm long. The body of the larva includes a distinct head, trunk and tail. The role of the respiratory organs is played by two pairs of small external gills. A fully formed tadpole has organs adapted for swimming and breathing; the lungs of the future frog develop from the pharynx.

Unique Metamorphoses

The aquatic tadpole undergoes a series of changes that eventually transform it into a frog. During metamorphosis, some larval structures are reduced and some are changed. Metamorphoses initiated by thyroid function can be divided into three categories.

1. Changes in appearance. Rear limbs grow, joints develop, fingers appear. The forelimbs, still hidden by special protective folds, come out. The tail shrinks, its structures break down and gradually nothing remains in its place. The eyes from the sides pass to the top of the head and become bulging, the lateral organ system disappears, the old skin is shed, and a new one, with a large number of skin glands, develops. The horny jaws fall off along with the larval skin, they are replaced by true jaws, first cartilaginous and then bony. The gap in the mouth increases significantly, allowing the frog to feed on large insects.

2. Changes in internal anatomy. The gills begin to lose their importance and disappear, the lungs become more and more functional. Corresponding changes are taking place in vascular system. Now the gills gradually cease to play a role in blood circulation, more blood begins to flow into the lungs. The heart becomes three-chambered. The transition from a predominantly plant-based diet to a purely carnivorous diet affects the length of the alimentary canal. It shrinks and twists. The mouth becomes wider, the jaws develop, the tongue enlarges, the stomach and liver also become larger. The pronephros is replaced by mesospheric buds.

3. Lifestyle changes. During the transition from larva to adult stage of development of frogs, with the onset of metamorphosis, the lifestyle of an amphibian changes. It often rises to the surface to gulp air and inflate the lungs.

Frog - a miniature version of an adult frog

From the age of 12 weeks, the tadpole has only a small remnant of a tail and looks like a smaller version of the adult, which, as a rule, completes a full growth cycle by 16 weeks. The development and species of frogs are interrelated, some frogs that live at high altitudes or in cold places can live in the tadpole stage all winter. Certain species may have their own unique developmental stages that differ from the traditional ones.

Frog life cycle

Most frogs breed during the rainy season, when ponds are flooded with water. Tadpoles, whose diet differs from that of adults, can take advantage of the abundance of algae and vegetation in the water. The female lays eggs in a special protective jelly under water or on plants located nearby, and sometimes does not even care about the offspring. Initially, the embryos absorb their yolk reserves. Once the embryo has turned into a tadpole, the jelly dissolves and the tadpole emerges from its protective shell. The development of frogs from eggs to adults is accompanied by a number of complex changes (appearance of limbs, reduction of the tail, internal restructuring of organs, and so on). As a result, the adult individual of the animal in its structure, lifestyle and habitat differs significantly from the previous stages of development.

After hibernation frogs and toads go to shallow ponds, ditches, puddles and spills well warmed up by the sun melt water. Here, the females spawn, very similar to fish eggs, and the males pour seminal fluid over it.

Caviar, as a rule, is laid a lot, with a margin, because from the stage of fertilization to the adult frog, countless dangers lie in wait for their offspring. Unfertilized eggs become white or opaque. If everything went well, you can observe the division of the yolk into two, then into four, into eight, and so on, until it looks like a raspberry inside the jelly. Soon the embryo begins to look more and more like a tadpole, moving little by little inside the egg.
On average, the egg stage lasts about 6-21 days, until the time when the larva hatches out. Most eggs develop in calm or stagnant waters to prevent mechanical damage to the eggs.

Tadpole

Immediately after hatching, the tadpole feeds on the remains of the yolk, which is located in its intestines. On the this moment the amphibian larva has poorly developed gills, mouth and tail. This is a rather fragile creature. The tadpole initially attaches itself to objects in the water using small, sticky organs between its mouth and abdomen.

Then, 7-10 days after the tadpole has already hatched, it will begin to swim and feed on algae.

After 4 weeks, the gills begin to overgrow with skin until they eventually disappear.
Tadpoles get tiny teeth that help them scrape off algae. They have long had a spiral-shaped intestine, which makes it possible to extract the maximum amount from the food they eat. nutrients. At this time, the tadpole has a developed notochord, a two-chambered heart, and one circle of blood circulation.
Interestingly, by the fourth week, tadpoles can be considered quite social creatures. Some are even able to interact with each other like fish!

Tadpole with legs

After about 6-9 weeks, the tadpole develops tiny legs and begins to grow. The head becomes more pronounced and the body lengthens. Now large objects, such as dead insects or plants, can also serve as food for the tadpole.

The forelimbs appear later than the hind limbs, with the elbow being detected first.

After 9 weeks, the tadpole looks more like a small frog with a very long tail. The process of metamorphosis begins.

By the end of 12 weeks, the tail gradually disappears and the tadpole looks just like a miniature version of an adult frog. He soon emerges from the water to begin his adult life. And after 3 years, the young frog will be able to participate in the process of reproduction.

Some frogs that live at higher altitudes or in colder places may take much longer to go through the tadpole stage. Others exhibit unique developmental stages that differ from the traditional tadpole-in-water life cycle type.

Is the life cycle of a toad and a frog different?

In fact, toads are the same frogs. Toads are just called differently, look a little different, but they are all part of the frog family. Many are wondering what is the difference between life cycle toads and frogs. Perhaps the main difference will be that frog caviar looks like clots, and toad caviar looks like ribbons or stripes.

What a frog looks like - everyone knows in the world. How is a frog born? Is it true that different types frogs reproduce and care for their offspring in different ways?

In this article we will talk about how nature arranged the process of the birth of the most. As a rule, these amphibians are born in a pond or lake. The female frog leaves eggs only in stagnant water. After a certain period of time, tadpoles appear from the laid eggs, then they turn into small frogs ... so we used to think, looking at the frogs that live in our country, but in fact ...

In fact, not all frog species reproduce in the same way. The main "innovators" in the reproductive field are those frogs that live in the tropics. Firstly, the number of species of tailless amphibians that we are talking about in tropical zones exceeds all conceivable ideas. A large number of predators, now and then wishing to feast on frog eggs, makes these amphibians invent the most different ways save future offspring.

Birth of glass frogs

Females produce caviar, which looks like a gelatinous mass. This "mass" is attached to the back of the sheet (it is important that the sheet is located directly above the water). The father of the family becomes a guard for future offspring. When the tadpoles emerge from the eggs, they slide off the leaf directly into the pond and there is already a further transformation into an adult.

Birth of the South African frog

Have you heard of "foam houses"? This is not just an unusual substance, but a real hiding place in which South African frogs hide their eggs. How is foam formed? In order to create such a “house”, the female frog secretes a special substance, and the industrious male beats it into foam. The top layer of the foam house hardens and the eggs can comfortably continue to develop inside without fear of being eaten.

Birth of poison dart frogs

Poisonous South American frogs give life to their offspring also not quite in the usual way. They, like their other relatives, lay eggs (by placing them on moist soil). Then they carefully and very jealously guard the eggs. Well, when the tadpoles emerge from the eggs, they immediately climb onto their back to their parent. What for? To move from the ground to the tree. Having found the leaves of the bromeliad plant (which winds around the trees), the mother frog places the tadpoles in a funnel at the base of the bromeliad leaf (where water always accumulates after rains). Here the tadpoles find a temporary shelter until their parent finds a nearby body of water and transfers them to it for later maturation.

Birth of the pygmy marsupial tree frog

Yes, yes, you heard right “marsupial”. By the way, the birth of cubs in this frog is similar to the way of reproduction in kangaroos. The frog has a special pocket made of leather, where the laid eggs are placed. Unlike the kangaroo, the tree frog has a pocket on its back. So a caring mother carries her future babies until the time comes for them to become tadpoles. Then the tree frog carries the future frogs to the reservoir and releases them.

The birth of the rain frog

The unusual structure of the eggs of these frogs makes it possible to be born not as a tadpole, but immediately as a small adult. The fact is that the internal composition of the egg is such that it has a sufficient supply of nutrients for the tadpole to feed and live to become a frog without leaving the egg shell.

tadpole tadpole

tailless amphibian larva. Develops from an egg. Lives in water, has outside. gills (2-3 pairs), a two-chambered heart, a long tail that serves for movement, an organ of adhesion, with the help of which G. is attached to underwater objects, organs of the lateral line. It feeds on arr. grows, food. After 3-4 months of development, G.'s metamorphosis occurs: the heart becomes three-chambered, breathing is pulmonary (the gills are reduced), the tail disappears, the hind legs grow, which become the main. movement organs. The horny beak disappears, the mouth increases, the intestines shorten. The cavity cf. ear and eardrum, eyes acquire moving eyelids; lateral line organs disappear. At the end of these changes, a young amphibian (for example, a frog) with fully developed limbs of a terrestrial vertebrate comes to land. (cm. LARVA) rice. 42 at Art., (cf. METAMORPHOSIS) rice. VI under Art.

.(Source: Biological encyclopedic Dictionary." Ch. ed. M. S. Gilyarov; Editorial: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin and others - 2nd ed., corrected. - M.: Sov. Encyclopedia, 1986.)

Larva of tailless amphibians. It develops from an egg, lives in water and has characteristics: two-chambered heart, external gills (2-3 pairs), long tail, organs sideline. A tadpole emerging from an egg appearance more like a fish than a frog or toad. It feeds mainly on plant foods, grows and after a few months undergoes metamorphosis : the heart becomes three-chambered, first the hind limbs appear, and then the forelimbs, the lungs form, the tail and organs of the lateral line disappear. The tadpole turns into an adult amphibian.

.(Source: "Biology. Modern Illustrated Encyclopedia." Editor-in-Chief A.P. Gorkin; M.: Rosmen, 2006.)

See what "TADpole" is in other dictionaries:

Umnik, wise man Dictionary of Russian synonyms. tadpole n., number of synonyms: 12 nerds (11) galaxy ... Synonym dictionary

Tadpole, larva of frogs, toads and other amphibians ... Modern Encyclopedia

Larva of tailless amphibians. Unlike the adult form, it has gills, a two-chambered heart, a long tail used for locomotion, an organ of adhesion, and lateral line organs. All these signs characteristic of fish disappear during metamorphosis, and on ... ... Big Encyclopedic Dictionary

Tadpole, tadpole, male. (zool.). Frog larva. Explanatory Dictionary of Ushakov. D.N. Ushakov. 1935 1940 ... Explanatory Dictionary of Ushakov

TADpole, ah, husband. 1. Tailed larva of tailless amphibians (frogs, toads). 2. About who big head(colloquial jest.). | adj. tadpole, oy, oy (to 1 value). Explanatory dictionary of Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov

tadpole- TADpole, a, m. 1. A man with a big head. 2. A small, nondescript person. 3. Iron. appeal... Dictionary of Russian Argo

Frogspawn development ... Wikipedia

Larva of tailless amphibians (See Amphibians). Developing from eggs, G. leads an aquatic lifestyle; has external gills, a two-chambered heart, a long tail that serves for movement, an organ of adhesion, with the help of which G. ... ... Great Soviet Encyclopedia

BUT; m. 1. Tailed larva of tailless amphibians (frogs, toads). 2. Expand. (usually joking). About someone who has a disproportionately large head. ◁ Tadpole, oh, oh. * * * Tadpole is a larva of tailless amphibians. Unlike the adult form, it has ... ... encyclopedic Dictionary

tadpole- Truck with uncoupled containers, trailers. Oh, look, the Tadpole has passed! Automotive slang… Dictionary modern vocabulary, jargon and slang

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