The main features of the biology of amphibian breeding are determined to a large extent features of the structure of their eggs that require for development, as a rule, an aqueous medium. A well-known impact on the nature of the reproduction also also has the degree of the grounds of one or another species, dependence of it from humidity and temperature.
Waking up from the winter hibernation, all our amphibians, with rare exceptions, accumulate in reservoirs, turning to the spring period by water inhabitants.
- Sexual dimorphism and adult adaptations to breeding in water
Since for ground amphibians, the spring stay in the reservoirs is connected only with the processes of breeding, then there are no insufficient individuals in reservoirs and lead a ground lifestyle. The brown frogs, the toads, quanks and garlics in the spring in the reservoirs and garlics are an exception.
Moreover, detailed observations of the spring way of the life of a nuclear frog show that during this species during the period of reproduction a more or less long time spend only males in the reservoirs, while the caviar who arrived in the reservoirs not yet noted by the caviar of females. The females not only come in the reservoir later males, but also, checking the caviar, now leave him. This explains the fact that in reservoirs is usually found a large number of single males and only pairing, not postponing female cavities. In the midst of breeding on land, you can meet or have not yet postponed the caviar of females going to the reservoir, or, on the contrary, females, postponed the caviar and removing from it. Samsya at this time does not happen on land.
During the period of reproduction, the males takes a significant growing of the membrane between the fingers of the hind limbs (Table 12 - the area of the foot was calculated in MM. 2 On a unit of body length and multiplied by 50, i.e., recalculated in relation to body 50 MM. .).
As can be seen, the swimming membranes on the hind limbs in the males of herbal and crooking frogs increase almost twice. The growth occurs due to the increase in the outer edge of the membrane, and the frog in a sharpness of the frog becomes convex (Fig. 14). The male pond frog, the membrane grow significantly less (less than one and a half times)
The back of the nasoid frog
The females, in contrast to males, the growing of the membrane is very insignificant, which is associated not only with their smaller activity, but also that they, compared with the males, remain in reservoir. This is especially true of terrestrial species, and among the last - a sharply frog.
The males of the ordinary triton during the reproduction period are on the fingers of the back limbs, playing the role of swimming membranes; The low-immiginal triton of these skin sutures on the fingers of the rear legs is not, but a wide border appears on the outer edge of the plus.
All of our tripitons in spring develop more or less wide spine and tail fins. These formations not only contribute to an increase in animal mobility in water, but also serve as additional respiratory authorities, thanks to a rich network of blood vessels (Fig. 15).
Common Triton Male
The formation of additional respiratory organs during the reproduction period is directly in line with an increase in mobility and metabolism. Since spring tritons are carried out all the time in the thickness of the water, it is clear that the strengthening of the skin of respiration, and not lungs play a special role.
The value of the dorsal and tail fins as additional respiratory organs is confirmed by the following data obtained in experiments over an ordinary Triton. The males of this species during the reproduction period at 15-16 ° are able to live under water without air respiration 99 h. 36 m., And females 84 h. 42 m. At 25 °, males survive 2 hours 35 m., And females 1 h. 54 m.
After the reproduction period, when the Tritons move to land and fins disappear, the timing of the survival of females and males without air respiration is almost equal or males die even rather (banners, 1948).
Interestingly, males of low-union triton, possessing the most developed comb reaching 19 MM. In the width, on the existing observations do not rise at all on the surface behind the air.
Despite the additional skin organs, the males of ordinary and comb tritons, compared with females, more intensively and light breathing are more intensively. This is evidenced by, for example, observations in an aquarium, where the males of these species rise to the surface behind the air somewhat more often than the females.
Thus, even with relatively "land" frogs, as well as in Tritons, for the period of reproduction, features are developing, adaptable to water existence (swimming meters, fins). In quite terrestrial species, these devices disappear or noticeably reduced now after the end of the reproduction period. At species that are constantly living in reservoirs, they are developed quite strongly, but they do not wear a seasonal nature.
Differences between the fields in amphibians concern not only those signs that develop from them in connection with the water being staying during the reproduction period, as well as a number of other features that distinguish males and females.
So, during the reproduction period among all amphibians reigns great arousal. This is especially true of males, which accounts for the recovery and attraction of females. The appearance in the reservoir that did not mark the caviar of the female of the Ostroeorda frog causes great activity among males, which in vain, repulcing each other, strive to capture her. A similar phenomenon is more or less expressed in other species. In this regard, males and their behavior, and a number of anatomical features differ from females. The males have larger eyes, all the senses are better developed and, accordingly, more brain. Actively looking for females, males turn out to be more mobile, and they have a strong musculature.
During the period of reproduction, the differences between the floors also appear in the marriage painting, the singing of males and in other characteristics. Thus, the fester or gear fins of Tritons and the rods on their hind legs are considered as a marriage outfit that is complemented by a bright blue pearl strip along the tail appearing during the reproduction period.
In addition to Tritons, the marriage outfit is pronically pronounced at a sharply frog and the Caucasian russian.
The spin and chest of the males of a crooked frog in the spring are painted in a bright silver-blue color, which disappears after the reproduction period. In addition to changes in the color, the pairing male of a crooking frog differs as if some of the whole body occurring due to the strong filling of subcutaneous lymphatic cavities.
The males of herbal frog during the breeding period is noticeably pigeon her throat.
The males of the Caucasian rim in the marriage period darker females. On the back they have rarely scattered red spots, which are sometimes in crater deepening. On the back, sides, along the lower edge of the lower jaw and on the corners there are numerous horizontal education in the form of pointed and several curved spines. The abdomen in its lower part is littered with black spots, which are also horny education. The grooves and tubercles on the back are coated with a solid corneum layer, the surface of which is uneven and forms in places strongly protruding thickening. All these horny formations are disappeared at the end of the marriage period during molting, and they can be seen on a dropped skin. After molting changes and the painting of the male is changing. On the back, the contour of the light-colored oblique cross of the lying cross, at the lower ends of which appears two light spots; The upper part of the abdomen takes marble color; Stripes on the hind legs become brighter.
In other of our amphibians, the color of the body does not change in the spring so much, but all the tones they acquire a special brightness.
The marriage outfit of amphibians, as well as other vertebrates, is likely to play a role when recognizing floors, attracting and excitement of females.
The same meaning, apparently, has a spring singing of males, characteristic of all of our elderly amphibians. The lack of voices in tales as it were compensated for bright marriage outfit and games (see below).
Most singing males are characterized by special voice bags - resonators that enhance the sounds published.
All green frogs, the resonators are placed in the corners of the mouth. When a frog publishes a voice, they are protruding out in the form of two bubbles on the sides of the head. At the pond frog, the resonators are purely white, in black and spotted gray or almost white, and in lake - gray or black.
All other admitted amphibian resonators are placed inside, under the skin of the throat. Green toads and woods are characterized by unpaired resonators. The loudly singing green toad male or a tree so inflaps great resonators that they become almost greater than the head of the animal.
The more powerful voice of the males is connected with them with more powerful, compared with females, easy, that among our species in particular is well noticeable in the gerson.
An increase in lungs in males can also be associated with greater activity and enhanced metabolism. In turn, large lungs lead to the development of more powerful abdominal muscles.
- Feedback, layout of caviar and fixtures associated with these processes
As caviar and sperm from the huge majority of amphibians stands out directly into the water, i.e., the fertilization of them is outdoor. This feature of amphibians is a primitive, common with fishery ancestors. It could only be preserved in such terrestrial animals for whom the development in aquatic environment is characteristic.
Among our amphibians, the outer fertilization is observed in all those who are eager and among representatives of the most primitive from modern tailed - families of the corner-up Tritons: from a four-pailed, Semirechensky and Ussuri Tritons.
In admitted fertilization precedes "mating". The males of elderly amphibians during the reproduction period, in one way or another, tightly clasp the female with the front paws. Without such a clamp, or "mating", the normal process of ikrometania does not occur.
The males of garlic, gods and rents hold a female in the lumbar region. All other are our amphibians - in the chest. However, the males of the toad and Kwaksh hug a female perfectly from frogs. The first brush of the male is placed with armpits, the second paws of the male converge on the chest in the female between her front limbs.
Reflex crumbbing in males in spring is very bright. On any touch to the body they react with clamping. The male holds the female very hard and hardly from it is separated. There are cases when the male crushes the female in his arms, but continues to keep it. Torn away from the female, he strives to grab it again and, if the females do not find himself nearby, it grabs other males, individuals of another species, fish and, finally, sticks, stones and other objects.
However, usually the male quickly corrects its mistake, dissolving the hug. This is due to the existence of various in various types of gender recognition mechanisms. Thus, for the male of one of the types of frogs, an identification feature is the volume of the hugged object and its silence, since the female who did not postpone the caviar when touched it usually does not publish any sounds and is distinguished by a significant thickness. Hugs are very quickly stopped if the hugged item is published by a warning jacket.
In one, the parties studied in this regard, the recognition of the floor is also occurring after an embrace occurred, with the help of the so-called warning vibration - an unclear vibrating, barely catchy sound, which is heard only if to keep the toad at a distance of several centimeters from the ear. This sound is perceived by the toad, apparently, tactful when contact with the body of an animal, emitting sound. This warning vibration causes the hugging male to immediately stop the arms (Sabwan, 1935; Nobl and Aroness, 1943, etc.).
I just laid down the caviar of the green toad female while trying to grab it takes a characteristic posture, pulling the front paws bent in the elbow joint, tightly pressing the rolling body to the substrate and producing as if repulsive movements back. When the female takes such a pose, the male quickly leaves her alone.
As a fixture to a stronger clamping of frogs on the first outer finger of the front paws, large, dark, rough corns smoothing after the reproduction period are developing.
Significantly stronger than these formations are expressed in brown frogs leading the ground lifestyle.
For herbal frog, a four-part-based corporee education is characterized (Fig. 16); For Siberian - two-part, all other frogs are not disseminated on the part. Somewhat smaller than the brown frogs, Corn at the toad are located on three middle fingers of the front paws.
Front paw of male herbal frog with "marriages"
In males, gallows are small black corns on the first and second fingers of the forelimbs and on the inside of the forearm. Horn formations are also available on the inside of three middle fingers of the back limb.
The tree of the corn is weakly developed, and they are absent in garlics and hangouts. Due to the phenomenon of clamping, it is clear that the front paws of males, compared with females, are usually distinguished by a more developed muscles and a heavy skeleton. Education to hold females from extremely land tropical forms that breed on trees take particularly bizarre forms.
The process of the Ikrometania, the next greeting female female, differs from various species.
So, in green toads, he is composed of two repeatedly alternating phases: the reservoir phases and phase of the teaching of caviar. In the reaches and female phase, and the male hugging takes the position of a calmly sitting animal, somewhat pressed to the ground. Both animals lie on the water completely motionless with half-closed eyes, only periodically producing sharp respiratory movements. At this point, they lose all caution and almost do not react to irritation from the outside. From time to time, the female moves a bit from place to place, so that the cord of the excreted caviar is wound on vegetation. Usually after each such movement, the female pulls the hind legs so that they come into contact in the ankle joint, and both feet form a straight angle with a shin; At the same time, she is a little bit flap. The latter serves as a signal for the male, which immediately raises and, as if comes with the fingers of the hind legs on the female hips, pulling up to 10 tweaking movements, highlighting cum. Then, the pair of animals is pretty longs a long time in the pose described. During this period, the females on the sides of the abdomen are well visible strong, wave-like, contractile movements and caviar there. Finally, the Phase of Peace comes, which continues at about the same time as the phase of the execution of caviar.
Very interesting, the process of laying caviar at the obstacle. The male, sitting on his back in the female, two medium fingers of the back legs captures the end of the caviar cord sticking out of the female claws, pulls the leg, and with it and the cord. Then he grabs this cord with another back leg and so acts alternately until the cord is over. Simultaneously with the stretching of the cord of the male fertilizes eggs. As a result, the egg cord turns out to be wound on the chem female in the form of several naisted loops, similar to the eight. After that, the male pulls this tangle behind him, until the larvae is taken. At the same time, one male can mate with several females and wear caviar from different females.
The layout of caviar and fertilization in contrast to most of other amphibians occur at the rents on land.
Ovulation, i.e., the yield out of the ovary in the oval, apparently, is performed normally and without the participation of the male. However, as our observations showed, if the females of various types of admitted amphibians in artificial conditions are separated from males, then in the majority they die because of the Ikra accumulated in the eggs strongly bursts them.
In other cases, such isolated females after 1-2 weeks were postponed to caviar, but the process of iketania lost its specificity. Caviar, as it were, flowed from the female, and there were no characteristic movements and the pose of ikrometania. The selection of sperm in the male, in all likelihood, is caused by the characteristic posture and movements of the female and the female.
The pairing of chickened amphibians described above with external fertilization has a large biological value. It provides simultaneous selection of caviar and sperm. In addition, due to the fact that when grabbing the cloakes of the male and females are brought closer, the sperm stands out straight on the eggs. All this increases the percentage of fertilized eggs.
In contrast to the taper-dotted amphibians, sexual dimorphism is developed slightly, there is a weak, no phenomenon of females coverage, there are no devices for their retention.
Eggs or fertilized by the males staying nearby after they are already postponed, or, as it takes place at the Semirechensky triton, the males attach a sperm package, the so-called "sperm", to some subject in water (stone, stick, etc. .), The female is attached to such a spermator attaching a mucosal bag with caviar (Fig. 17). From the sperm spermatozoa, they enter the bag with eggs, where fertilization occurs.
Sproduce and firebags of Semirechensky Triton
Other our tailed amphibians are in the nature of fertilization stand at a higher degree of development than corner-up Tritons and taught amphibians. They have fertilization of the internal, but there are no copulative organs.
Tritons in fertilization precede the lively marriage games. At the same time, the animals hold in pairs, they swim together, then closely pressing, then somewhat moving away from each other. A pairing male lifts the comb, quickly moves them and then brings his head to the head of the female. At this time, he continuously moves the tail and so bends him so much, which strikes the female on the sides. Marriage games occur during the entire period of reproduction. As a result of these games, the male is postponing journalist lumps - spermatophores containing seed. Sperm attachments are attached to the surrounding subjects or at the bottom, and the female excited by the games finds them out and grabs the edges of the clock. From Cloaca, the sperm enters into a pocket-shaped deepening, the so-called sperm. Hence the sperm descending, fertilizing the eggs gradually passing out of the eggs.
Several otherwise goes to fertilization from terrestrial species. So, the fire salamander fertilization occurs on land. The male hugs the female and twists so much that their cloaches are brought together and the cone-shaped sperm goes into the female clock. In some cases, fire salamander fertilization occurs in water and then does not differ from the method of fertilization of tritons. There is an assumption that the fire salamander has the perception of the seed of the body of the female in the fall, and fertilization is early spring (Angel, 1947).
The males of the Caucasian Salamandra on the upper surface of the tail, in its foundation, special glands are placed, which excreted the exciting female. Such glands are characteristic of many tropical amphibians, mainly ground forms. On the shoulder of the Caucasian Salamandra there is a roller, which serves to better retention for female in fertilization.
- Masonry form, number, sizes and build eggs
All our frogs are characterized by a laying of caviar in the form of a larger or smaller lump formed due to gluing mucous membranes.
Freshly chosen caviar in the reservoir is easy to find out, as it is a small lump of the eggs closely adjacent to each other. Gradually, as mucous membranes swelling, the distance between individual eggs, as it were, and the entire lump acquires a significantly larger volume (Fig. 19).
Masonry caviar of hellless amphibians
Brown frogs lay the caviar near the shore on small, outstanding, well-warmed places. In one place, the mass of caviar with many females usually accumulates.
Our green frogs lay the caviar most often among aquatic plants.
Also lumps are postponed by caviar Kvakshi, but they have no lumps of caviar, due to the fact that they contain a smaller number of eggs and the ikrinka themselves are twice as smoother than the frogs. Each Ikrinka Kvakshi has its mucous membranes. Ikra is postponed in shallow water, at the bottom of the reservoir (Fig. 19).
In the rest of our amphibians, all the laying is surrounded by a common mucous membrane corresponding to the outer mucous membrane of a separate egg in a whirl in a frog. In the Siberian four-pailed, Semirechensky and Ussuri tritons, the laying was enclosed as it were in a bag of various shapes formed by the outer mucosa (Fig. 20). Semirechensky triton, ice bags have an elongated sausage form from 6 to 30 cm Length and contain up to 50 icons (Fig. 17).
In the Ussuri triton, the icer bag is approaching an ellipse form. Each bag is placed from 5 to 7 eggs (Fig. 20).
Calf cakes in four-pailed triton, clawed triton and ordinary triton
In a four-pailed triton, the laying has the shape of a cone-shaped spiral. One end of the spiral is free, and a relatively thin, short mucosa lace is attached to another, which further goes into the same mucous film, covering the branch of the underwater plant, and binds two glasses with each other. The diameter of the bag in its mid 19-22 mm, Length 180-190. mm. In each bag of 60-40 eggs. Each egg lying in the bag has its own mucous membrane (residents, 1900).
Such (usually paired) bags are attached to stones, plants and other subjects low above the water level, so most of the masonry turns out to be in water and in the mining species - the Ussuri and Semirechensky Tritons ranges from side to side due to the rapid flow.
Thick, sausage cords formed by the outer sheath of eggs and containing inside a number of randomly located eggs, lay the garlic (Fig. 19).
Icroids occurs under water, and the cords are enveloped underwater objects: fallen bits, twigs, algae.
The Caucasian Handling Closemark is similar to the masonry of garlic. In typical cases, it has the shape of a cylinder, inside which some item passes on the longitudinal axis - a branch, a twist or herb. Caviar is postponed in the Mountain River Creeks or in places with slow flow, as well as in closed but not contaminated reservoirs.
Eggs at the toads, located in two, three or four rows and coated with a common outer sheath, form thin cords that pass underwater plants or branches and twigs in the water (Fig. 19).
Cords from fastenly located in one row of eggs covered with several shells are characteristic of obstacles (Fig. 19).
Unlike all our amphibians and Tritons put single eggs.
In Serbanka, eggs are more often located in groups near plants or other underwater items in the thickness of water, but are not connected with each other (Fig. 19).
Tritons always put eggs one. Great Triton sticks the eggs to various parts of the plants so that the egg is hidden in plant, mass. The ordinary Triton lays out the egg on, the sheet, the part of which is then bends the rear paws, so that the cheeky turns out to be hidden between the two sheets of the sheet. Adhesive to Ikrinka, a bent leaf, remains in such a state until the larva hatch (Fig. 20).
Thus, the masonry of our amphibians in shape can be located in the next row (Fig. 19):
Rounded egg bags, extend, turn into, thick cords, the last, extending in turn, give thin cords. Of these, there are clear-like single-row cords. When a break in intermediate between eggs, single eggs are formed. These last thanks to the stickiness of the shells can be repeatedly glued in lumps, bugs, etc., while maintaining, however, all their shells are isolated.
Finding out the question whether this series is evolutionary, requires special research.
Single launching of eggs to the shelter with which we meet in Tritons can be viewed as the simplest "care of the offspring", as such eggs are less available for a predator.
An even greater care for the offspring shows a hangup, the male that pulls the caviar to the caviar until the hatching of the larvae.
Finally, among our amphibians, the highest degree of care for offspring is found at Salamandr.
All stages of the development of caviar at the Spotted and Caucasian Salamandra occur in the shames of female, and the corrugated larvae finish their development in water. The Black Alpine Salamandra has a view close to Spotted Salamandre, this process went even further, and she has not only eggs, but also the larvae develop in the ovitsa, and there are already quite formed small salamanders.
The Black Salamandra from 30-40 released eggs developed only two eggs. All the others remain unopened and go to the nutrition of developing embryos. These neglected eggs merge into one surrounding embryo the nutrient mass, in which the germ can move freely at the exit of the egg. The nutrient mass in the malfunctions of the mother replaces the water medium necessary for the larva. By the birth of the baby, all nutritious stock is used.
For those amphibians, which are characteristic of the internal fertilization and one or another care for the offspring, characterized by a small number of laid eggs (see Table 13).
Spotted, or fiery, Salamander will give birth from 8 to 70 larvae. The obseruha postpones 60-120 eggs, Tritons from 60 to 200.
At the same time, there are a huge number of eggs in other amphibious, deprived of the care of offspring. In frogs, for example, they are from 600 to 10,000, at the toads from 1200 to 12,000 eggs, at Quix from 800 to 1200, etc.
In species that postpone the smaller amounts of eggs, they differ in large amounts due to an increase in the supply of nutrients - yolk (Table 13).
Quite accurate data on the number of eggs of the eggs with one or another type of amphibians we have very little. Table 14 provides information for some of our species.
The oscillations in the amount of laid eggs in the same species are associated with changes in the fertility of the species in different parts of the range. Nonodynakova fertility and in different years. Finally, the number of laid eggs depends on the size of the female. The latter illustrates Figure 21, where the dependence of the number of produced eggs from the size of females of a olom-died frog is shown (the authors of 74 females from the reservoirs in Ostankina in 1947-1948. Eggs were calculated completely in the body cavity and eggs after the end of ovulation, but until the end of the masonry). It can be seen from Figure 21 that the number of eggs increases with an increase in the sizes of female. However, this increase goes only until a certain point. So, in females size 69-70 MM. (Dimensions, almost limit for the form) Fruitness falls again. The latter, apparently, is associated with the weakening of the body in terms of marginal age.
The dependence of the number of produced eggs from the sizes of females at a sharp-edged frog
Ikrinka of various amphibians differ not only in the size of the yolk, but also by the magnitude and structure of the mucous membranes. Eggs taped, as a rule, have thicker egg shells and a small periviteline space, and the eggs of tailed amphibians, on the contrary, are thinner and dense shells and a large periviteline space (Fig. 22).
The structure of the eggs of amphibians
In the egg shells of admitted amphibians (frogs, toads, kvaars, garlic) There are no structures - they are quite homogeneous. Only in the province, in the compacted inner layer, apparently there are weakly distinguishable fiber education.
In the more dense egg shells of tailed amphibians, in particular, in the inner, most dense, layer there is a fairly pronounced fibrous structure. Fibers fine, transparent and pass parallel to the surface of the shell. Tritons are scheduled for two systems of fibers - meridional and transverse. Bundles of the latter are found over the top of the shell (Sergeev, 1937).
Significant interest is the structure of the shells of the EMICs of the obstacle as amphibious with terrestrial development. Here fibers make up the basis of the structure of the egg shell. In addition to fibers, there is a uniform, transparent intermediate. The magnitude of the fiber is more defined than tritons. At the motley, they form a number of layers, and each layer consists of one row of fibers lying, in general, in parallel. However, every fiber is far from straightforward: there are bends, some fibers are branched. Systems of two adjacent layers intersect at right angles.
The appearance of fibers in the shell facilitates its strength. Indeed, the density and strength of the egg shells of the triton, compared with the egg shells of frogs and the toad, are very large.
To an even greater extent, this is noticeable when comparing the egg shells of aqueous admitted amphibians with an egg shell of terrestrial pointing. Egg shells are so hard that the touch seems to be leathery. The occurrence of a durable egg shell at the obsechi is associated with the transfer of eggs on land, where they are dangerous dry, as well as shocks and pressures, much more dangerous than in water, due to the greater the specific weight of the eggs in the air. On the contrary, the swelling, so characteristic of soft shells, hard shells are almost absent, the egg in the last division of the egg is already quite formed and has the same appearance as after the tab. Apparently, the shell decorated into fibers is already deprived of the opportunity to swell to such an extent as homogeneous.
In most cases, the eggs with a fibrous shell are postponed by one. So, from the lower paneous amphibians, only one gallow has a single eggs, and it is her who has a compacted egg sheath. The ordinary Triton lays singing eggs with a dense shell, and a four-pailed Triton - a representative of another family, having egg bags, is distinguished by soft egg shells, etc. The reason for this can be seen in the fact that the eggs combined into the masonry are less subjected to mechanical effects, for Pressure is distributed to many eggs
In general, the extraordinary elasticity and flexibility of the eggs of eggs of all amphibians makes them beautiful shock absorbers with all sorts of mechanical effects on the egg. This property of the shells along with their mucousness leads to the fact that the masonry of amphibians, especially in the form of a large lump, are almost inaccessible to predators. Indeed, it is extremely difficult to keep the commercial caviar or tear away from it. Thanks to this, the caviar of amphibians eaten only some ducks and predatory water beetles.
Transparent egg shells in most species are collective lenses concentrating light and thermal rays on the egg. This, along with their low thermal conductivity, increases the temperature in the masonry.
Thick shells also interfere with the rapprochement of eggs among themselves and thereby contribute to the best aerations. At the same time, algae will be settled on the shells, and this improves the oxygen mode of eggs. On the contrary, thanks to the peculiarities of their chemical composition, they impede growth on bacteria eggs.
The stickiness of the shells in some cases provides the possibility of icons to stay on plants, stones, etc.
Shells reduce the proportion of eggs, increasing their surface. This, along with gases sticking to the shell, in a number of species helps to pop up eggs on the surface of the water.
Finally, the shells serve as feeding larvae in the first days of their lives. In addition, the tadpole is kept on them, it is not demolished and does not fall on the bottom.
Despite the fact that in the conditions of experience, an egg, devoid of shells, develops faster, in nature they perform a very diverse function and are vital.
- Terms of breeding
Previously, the other wakeful herbal frog is postponed by caviar. On average, the Icres tab near Moscow begins on April 22. For eleven years of observations, the earliest output began on the seventh of April, the most late on May 3.
Following the herbal frog, Icru of Ostroyordy puts, then it begins and the tritons from both species of Tritons begins. Early timing of IKRA laying is characterized by a four-pailed Triton, which caviar appears at the end of April.
The early layout of caviar in these species is apparently associated with their low-resistant to low temperatures.
In early May, the Icres layout begins at the toad and garlic. Reed toad in Western Europe and Mongolian in Transbaikalia Icru sworn in the first decade of May. In the second half of May, the caviar of Serbians appears, then the lake frog and, finally, the pond.
Of all the studied species rising in the mountains, the most early breeding time are characterized by: a Caucasian frog, a beginner of the Ikrometania at the end of April, the Caucasian Salamander, mating in the second half of April, and the fiery Salamander agenvustive appearance, which is a massive childhood.
Later, it is characteristic of such mountain types, as the Caucasian russian, whose first caviar is marked in early June, and Semirechensky Triton, laid by caviar at the end of June.
Mass chrometh in green toads and a lake frog in the mountains of the Caucasus at an altitude of 1600 мIt falls on the second half of July, and in the valleys, green toad, in cases of strongly protracted reproduction, mosk caviar in April-May.
Quake, starting in the mountains to Ikrometania in late May, in the valleys mosquitated caviar at the end of April. The Caucasian frog in the valleys is postponing the first caviar in March (instead of the end of April in the mountains).
Accordingly, it also begins with wintering in the south earlier. So, in France, the obstacle begins to multiply from March, in Germany, the mass and cryometics of this species falls on May. In the predfaccise, the ordinary Triton begins with a cryometric in early April instead of the end of April near Moscow. Green toad begins to throw caviar in the predfabcasus not at the beginning of May, as near Moscow, but in April.
Types such as brown frogs, ordinary toad and garlic, are characterized not only by early dates of icomet of, but also by the fact that they begin to reproduce shortly after awakening. It is known that pairing in herbal and crooking frog begins on the way to spawning reservoirs.
The females of herbal frog, who had just left wintering, all caviar had already ovulad and was in the last thin-walled, stretched eggs, ready to teach. Already 3-5 days after their awakening in spawning reservoirs, you can find a freshly chosen caviar. The masonry of a crooking frog appear 6-8 days after the start of spring activity.
For other amphibians, for example, green frogs and gods, the first caviar appears 15-20 days after their awakening.
The process of reproduction of brown frogs, ordinary toads, quanks, garlic and four-pailed triton differs by another feature - the brevity of the period of ikrometania. The females of all these species, with the exception, perhaps, a four-pailed triton, which there is no sufficient information, sweep the caviar at a time.
Kvakshi Icra is postponed by several lumps, following each other. The whole process of icometope takes from 2 to 48 hours. All eggs in the listed species ripen and ovulate simultaneously. In the body cavity it turns out the mass of eggs. All of them for several hours are captured by the funnel of the eggs and, having passed on the eggs, accumulate in the expanding finite part of them, differing extremely thin walls.
Interestingly, the farm funnel of the eggs griest to the windowless bag and, together with it, performs pulsating movements, tightening eggs into eggs. This feature should be considered as an adaptation to rapid passage through the eggs of a large number of eggs ovulating simultaneously.
The ovary u had just laid out the caviar of the female very small and contains tiny pieces of eggs that will be postponed next year. Throughout the summer, the eggs are increased in size, change the color and the autumn acquire the species of mature. They are postponed by the next spring.
The reduction in the deadlines of the ikrometania in terrestrial species is also achieved by the fact that all hawk individuals, the ripening and exhibition of eggs occurs more or less simultaneously. So, usually all the gray toads of this area are made by caviar for 6-8 days, and brown frogs for 10-15. A slight period of time spends in water coming here to lay caviar and four-pailed Triton.
Compared to the above species, the period of ikrometania in other amphibians is significantly stretched.
Green toad and, apparently, reeds lay the caviar with one portion. But in them in some years, the oscrament layout can occur with different individuals undesuned, and then the ikrometania is significantly stretched. So, at the reed toad, the Icra tab comes from April to September, the green can be delayed until August.
All other of our amphibian - green frogs, hanging, horseradish, Caucasian russia and real tritons are more or less long time and are constant and are associated with the fact that the caviar is postponed by several portions. Accordingly, the maturation and ovulation of eggs occur also not at the same time.
Green frogs sword caviar 2-3 times, postponing every time big lumps of caviar. Repeatedly molded to caviar of the oborce. Young females put the caviar usually three times, old - four. In the spring, one masonry should be shortly over the other, and by the end of May, only one portion of caviar remains in the eggs, which is postponed later.
Several times small portions put the caviar of the caviar. Within 2-5 days, there are lives of a living baby fiery salamander. And finally, the females of Tritons throughout the almost two or two and a half months are postponed several eggs per day.
For species with a stretched idleness, the unlimited oscrament tab is also characterized by different individuals.
The reproduction and the Caucasian russian also stretched. It continues three to three and a half months old (from the second half of June to mid-September). Compacts in September, frosts do not stop ikrometania. What is the reason for such a long time of Irmetania from this species - it is unclear, since in the literature there is no data on how many times a year I caught one female (Changturishvili, 1940).
After Ikrometania, terrestrial types of amphibians leave the reservoirs. Females usually leave the first, and single males are found in reservoirs for a long time.
The duration of the time of the Ikrometania largely determines the period that land types are carried out in reservoirs. So, the gray toads are delayed in reservoirs of 6-8 days, herbal frog is about 15 days, a keen on 12-14 days, garlic 20-25, quanks 25, Tritons about 50 days.
If we take into account that females leave the reservoirs before males, then the specified deadlines of the ikrometania will be even more compressed.
The females are the same, whose fertilization occurs on land, do not go into reservoirs at all, and males are sent there when the hatching time is coming. Having shook off the caviar, from which tadpoles are very quickly hatching in the water, the male leaves the reservoir again. This species represents how the next step of separation from the reservoir.
- Development conditions YIITS
Different duration of waking up and the ikrometania of various species determine the conditions for the development of caviar. First of all, it concerns temperature conditions. It is clear that the temperature of the water in April is lower than in May-June, and is subject to significant fluctuations.
For example, near Moscow on April 19, 1948 in shallow water ,! where the caviar of the olkorda frog developed, the water temperature during the first day ranged from + 4 ° to + 14 ° C, i.e. 10 ° in two days, April 21, the cold came and the air temperature fell below zero, there was a small snow, Water in small places where the caviar was placed, covered with an ice crust. The highest temperature marked for water in the locations of the Icres of this species (for the entire period of development), reached + 23 °; The smallest + 1 °.
The development of caviar in the temperature conditions described above turns out to be possible due to the fact that the eggs early breeding species are very resistant to low temperatures. Thus, an egg of a herbal frog is normally developing from +1 to + 25 ° and withstands overcooling to -6 ° C, without losing development ability.
Of great importance is also the fact that the temperature in lumps of caviar is always higher than in the external environment. During the day, the temperature in the olkrokorda frog, an average of an environment exceeds the temperature in the environment by 3 °, the maximum difference occurring on the warm and solar time of the day is 7 °; The minimum in the coldest time of the day -1,5 ° lump of caviar is heated stronger and faster than water, and cool slowly. This phenomenon is explained, as we said, the fact that the transparent mucous membranes of eggs of most of the types of amphibians are collective lenses concentrating light and thermal rays on the egg. A large thermal inertia in Kemki caviar is also explained by the low thermal conductivity of the shells.
A reinforced absorption of heat rays also contributes to the accumulation of the dark pigment on one pole of the egg, facing the light. It is very typical that the caviar of amphibians developing in shelters is almost deprived of the pigment. So, the tritons attaching eggs on the bottom of the sheet or wrapping them into the leaves are yellow-greenish or slightly brown weakly pigmented eggs. On the contrary, the frogs and the toad are openly laid caviar. The most pigmented eggs of those species that are early breeding.
Pigment, absorbing thermal rays, at the same time is a shirma enclosing an egg from the harmful effects of ultraviolet rays. Eggs irradiated with an upigmented pole dying (Sergeev and Smirnov, 1939).
For the development of eggs, the choice of places for ikrometania is also important. In small places, the caviar absorbs more sunny rays.
A completely different conditions are the caviar of green frogs, developing in May-June at higher temperatures. The water temperature near the caviar of the lake and pond frog usually does not fall below 16 ° and does not rise above 31 °.
Amphibian egg development speed is directly dependent on temperature. The higher the temperature, the faster there is a development. In this regard, the eggs of herbal frog are developing an average of 8-10 days, and the caviar of the pond in the same reservoir is 3-5 days.
However, the eggs of the same species in the same area can develop different times, depending on the nature of the reservoir, and the oscillations can be very high. Herbal frog eggs in a deep shaded pond with a temperature of 6-8 ° develop four times slower than eggs, pending in a well-warmed puddle with a temperature of 22-25 °. In this regard, it is difficult to indicate any certain deadlines for the development of caviar in one or another. In different geographic locations and in different reservoirs, they turn out to be different. Southern types and types that fantastic caviar later are characterized by a faster development of caviar.
However, with the same temperature conditions in the experiment, the rate of development of herbal frogs is the greatest; She is somewhat less pond and minimal in garlic.
Thus, the consequence of the development of amphibious eggs in the aquatic environment will be:
1) the features of distribution and placement on biotope;
2) morphophysiological adaptations of adults to a water lifestyle or to change the habitat during the year;
3) external fertilization (in a huge majority of species);
4) Development with transformation.
At the same time, the peculiarities of the biology of reproduction and the development of amphibians depend on the degree of ground of the species.
Thus, the temporary development of the swimming membrane is expressed particularly sharply in terrestrial species; The same concerns the seasonal change of respiratory organs. Also, terrestrial forms are particularly strongly developed by the devices associated with the involvement of females (painting, voice) and withhold them in fertilization (marriage corn).
All of these features are aimed at accelerating the reproduction process, and thereby to reduce the period of stay in the reservoir. The extreme members of such a biological series that breed outside the reservoir have these devices particularly sharply pronounced (see the chapter "cases of ground development").
Ground views multiply aquatic, as they differ in greater resistance to low temperatures. The ability to maintain activity at relatively low temperatures is developing from terrestrial species precisely because they are forced to feed in the most humid time of the day, which is usually both the most cold.
In addition to early reproduction for terrestrial species, a reduction in the timing of ikrometania is characteristic.
Early reproduction and reduction of the timelines for land species leads to the fact that neither adult shapes nor developing larvae face or almost do not face water bodies with water species, thereby avoiding competition.
Brown frogs come for breeding into a biotope, inconspicuous at another time of the year. The green frogs breed there, where they dwell constantly. In this regard, during the breeding period, the so-called "marriage post" takes place during the breeding period. It is expressed in full or partial starvation of individuals during the reproduction period, i.e. during their stay in the reservoir. This is determined by the fact that early spring insects over the reservoirs is still very small, and in the water, the brown frogs are almost not taken. The reduction in the period of the ikrometania shortens the "marriage post", allowing terrestrial species to raise ordinary habitats on land, which can already provide them with food. At the same time, green frogs, partially taking prey in water, immediately after awakening can be fed.
Next, we are observing the spawning of brown frogs often in such reservoirs that are drying up by the beginning of summer. Late deferred caviar in these cases would have died. This phenomenon is observed in the years of the drought, when the headastrics of the brown frogs die in the mass, which does not happen to the casuals of green frogs inhabitants in constant reservoirs.
Finally, the brown frogs at the end of the metamorphosis are deserted over long distances. The period of settlement takes time. As observations show, it takes over the tiny segments all summer, until the start of the concentration of wintering places. Seboolets of green frogs remain where they are metamphized. Under such circumstances, the early durations of the reproduction of ground species are adaptive.
The same biological meaning also has an earlier larvae in terrestrial species and shortening the period of their development, allowing to avoid competition with larvae of later breeding species, to use temporary reservoirs to continue to grow on ground habitats.
Our toads as ground forms that have the shortest period of development of larvae penetrate into such arid areas where other types cannot dwell. At the same time, in the desert, green toad often uses not only fast drying reservoirs, but also sprinkled to the beginning of the summer, where species with a long larch period would not have time to complete metamorphosis. Being a thermal-loving form, which does not go to the development of caviar and larvae at such low temperatures, like the brown frogs, the green toad in the middle lane postpones caviar for 18-25 days later, the brown frogs, but the metamorphosis of the larvae delays it only for 10-16 days Compared to herbal and crooking frog. Thus, despite the thermal lubrication of the green toad, the short larch period allows it to penetrate it away to the north.
Apparent exception is garlic. This very terrestrial species starts to and crumble late, and the larvae develops exclusively for a long time, up to 90-100 days, reaching very large sizes. In some reservoirs, the larva do not have time metamorphy in one season. However, this exception actually only confirms the rule. The peculiarity of the biology of segolets is that they do not settle in the year of metamorphosis on ground biotopes, like brown frogs and toads. Metamorphsirovating, garlic ferments here on the shore of the reservoir are buried in the soil, where they remain until spring of next year (banners, 1956).
Reproduction and development of amphibians
Improvered amphibians in small, well-heated areas of water bodies. In the warm spring evenings with ponds and rivers, loud piggy sounds are spread. These "concerts" arrange males frogs to attract females.
Proposition authorities in males of amphibians, like fish, serve semenniks, in females - ovaries. They are located in the body cavity, the reproduction time increases many times. Ripened eggs in the ovaries fall into oval. During the movement of the eggs, the eggs are covered with a transparent mucous membrane and through a clock is displayed out. In the masonry of the herbal frog contains up to 1.5 thousand eggs. In males, the seeds that have an oval shape, allocate many movable spermatozoa. Seed liquid rich in spermatozoa, in the seeds, falls into the clock and stand out out. Fertilization in amphibians outdoor. The bunches of fertilized caviar are attached to aqueous plants or separate lumps floating at the water surface. Tape fertilized caviar Zab like separate eggs Triton , glued to the leaves of aquatic plants.
Consider the development of amphibians on the example frogs . The development of its embryo in Ikrinka lasts about one and a half weeks. Then the embryo breaks the shell of the icird and goes out. In appearance and lifestyle tadpole Looks like fish. He has gills, a two-chamber heart and one circle circulation circle, side line organs.
In the process of development, important changes occur in the headstand. The rear first develops, and then the forelimbs. Lungs appear, and the headstand is increasingly and more often rises to the surface of the water for breathing. In connection with the development of the lungs, the second circulation circle is formed, the heart becomes three-chamber. The tail gradually decreases. Golovastic becomes like an adult frog. Frogs from vegetable food goes to animal food consumption (becomes carnivore ) And leaves the reservoir. From the time of laying of caviar before turning the headstuffs in the frog passes 2-3 months.
Adult frogs have no tail. They begin to multiply aged 3-4 years.
Caring for the offspring of amphibians
Most frogs and toads lay eggs in water and leave them unattended. However, many species of amphibians are observed interesting forms of care for offspring. So, female Suriname Pips Sheets icers in skin cells on the back. Male Rinoderma Darwin Stores Ikrinka in your special throat bag. Woody grabbing frogs Inhabiting in Africa, postpone the caviar into a frothy secret on the leaves of trees located above the water. Halked thaws fall straight into the water. Female Two-color tree Sheets to the caviar into the leaves filled with water. The larvae, published from the cheek, stick to the back of the male, who spreads them into the "individual" reservoirs.
The influence of seasonal changes in nature on the life of amphibians
Annual life cycles in amphibians are well expressed in moderate latitudes with sharp seasonal changes in living conditions.
When the average daily temperature is lowered to +12 ... +8 ° C, amphibians move to wintering sites, and with further decrease in temperature in September - early October, they are hidden in shelters. In search of wintering places, individual individuals are moved to many hundreds of meters.
Ozerna, Pondovaya и Herbal frogs Winter in reservoirs, gathering several dozen individuals together, hide under stones, among water plants, buried in il. They choose the deepest areas where the reservoirs are not freezing to the bottom.
Toads, Gerlyanka, Tritons, Salamandras Winter on land: We are climbed into the holes, the holes of rodents, are hiding in the trunk of rotting stumps, under the stones, etc. In the harsh minor winter, when the Earth freezes on the greater depth, the amphibians in it will die more than wintering in water With a decrease in body temperature below -1 ° C, amphibians die.
Winter amphibians are in Catching: They dramatically decreases the metabolism, 2-3 times the absorption of oxygen is reduced, the number of respiratory movements and heart abbreviations decreases.
In the spring, with the onset of heat, at the end of March and in April, amphibians are moving towards an active lifestyle, leave the places of wintering and are sent to the reproduction places. These spring movements are fairly friendly, animals overcome hundreds of meters, getting to small, well-heated by the sun of reservoirs.
After breeding Brown frogs, toads, quacs Go to your usual summer habitats in the meadows, in the fields, gardens, gardens, etc. Tritons и Gerlyanka Conducted in the reservoirs for another 2-3 months, and then go to the land.
Interactive Trial Lesson (Go away all the lesson pages and do all tasks)
Amphibians - separate animals, multiply in water. Females sweep the caviar, males isolated seminal fluid. Outdoor fertilization. Development with transformation: from eggs are similar to cungal fish, which are transformed during the development of an adult amphibian. The lifestyle of amphibians changes depending on seasonal changes in habitat conditions.
Reproduction of amphibians
Reproduction . The main features of the reproduction of amphibians are determined to a large extent features of the structure of their eggs, in most cases requiring reservoirs. The well-known impact on the nature of the reproduction is also humidity, and ambient temperature.
In the enormous majority of amphibian fertilization outdoor. Internal fertilization is peculiar only with a non-branded and some tailed. In adversity, it is extremely rare, in 2-3 species. However, in contrast to fish, even in those amphibians, which are characterized by outer fertilization, mating occurs.
1, 2 - Trituration Ordinary (Triturus vulgaris); Z - greenish
Triton (Diemictylus ViridesCens); 4 - the text of Salamander (Desmo-
It is missing only in some primitive tails with outdoor fertilization. Selection of partners for mating in herbal frog occurs at similar sizes. Scientists suggest that these amphibians have a tendency to preferably mating individuals close to age.
The male gravily gripped firmly worst female with front paws. The manner of clamping is different from representatives of various systematic groups. Pairing is of great importance for amphibians. It provides simultaneous selection of caviar and sperm. In addition, due to the fact that when grabbing the Cloaca of the male and females are brought closer, the sperm stands out straight on the eggs. This increases the percentage of fertilized eggs.
Secondary sex signs in the structure of the front feet of the Novogvinsky toad (Lechriodus): 1 - the right leg of female below; 2 - the right foot of the male below
Amphibian with internal fertilization, as a rule, do not have copulation. Only at the gadless, the collapse of the males serves as a copulative organ.
Tritons, like most other tailed, males are postponing journalist lumps - spermatops containing seed. They are attached in water to the surrounding objects or the bottom, and the female grabbing their clock edges. From Cloaca, the sperm enters into a pocket-shaped deepening - sperm, and the liberated cerematozoa cerematozoids as needed fertilize gradually moving past eggs.
Sexual dimorphism in the structure of the front legs of South American whistle LeptoDactylus Ocellatus:
1 - female; 2 - male.
The ground taped amphibians of the male worst female and twists around it so that their clocks come into contact and the sperm goes into the female clock. As an adaptation to a stronger wretch of frogs on the forelimbs, rough formations are developing on the front limbs - marriage corn, which have different shapes, location and color. The front paws of males compared to those of females are usually distinguished by a more developed muscles and a heavier skeleton.
During the reproduction period, the whole range of amphibians changes coloring and a bright marriage outfit appears. Most often, its own owners are males, but some species are characteristic of females. In males, waning females, larger eyes, all the senses are better developed and, accordingly, more brain. Most singing males are characterized by special voice bags - resonators that enhance the sounds published by the male.
Possessing a more powerful voice, males differ from females and more developed lungs. Perhaps this is associated with greater activity and enhanced metabolism. The increase in lungs is accompanied by the development of a more powerful abdominal muscles.
The voice activity of males varies from different species. The males with a variable quacket (Hyla Versicolor) use the pairing acoustic signals, as well as specific signals of the meeting to protect the boundaries of the territory. With violators of borders, males come into a fight, in which, as a rule, wins the owner of the territory. The second male leaves the territory or remains silently on it, without attracting attention. During the pairing of dominant males, subordinates, who did not singers begin to make screaming cries.
Tree, inhabiting the south of Central America and large antillese acute, also territorial animals and their groups are hierarchical relations. The violation of them causes between the males the fight, which can be warned by special cries. Ready for reproduction of the male short trills calls for a female.
Kvakshi Hyla Cinerea in Northern Illinois is known three types of screams. The first one is distributed during migration from the shores to the center of the reservoir, the second - during aggressive contacts of males. The choir of votes from the screams of the third type stimulates the mating, by the time of its termination all females in the reservoir mate.
Puertorikan whistle (Eleutherodactilus coqui), males make a bounced sound "KI". It is assumed that this type of different parts of the male calls are performed by different functions. The first serves to prevent other males on the employment of the territory, the second - to attract females.
Field and Experimental Research on the Pairing of the Royal Quake (Hyla Regilla) showed that the females choose males on the strength of the voice and duration of the scream. The choice of females falls on the leaders of the marriage choir, beginning a cry before and ending it later than other males. Royal Quake in the laboratory conditions of the University of California published three different screams. A two-phase cry was collected by males together and attracted females, while the monophasic cry and trill performed the distribution function of males.
The voice repertoire of the bull frog is distinguished by a significant variety of screams that perform different features. These are the marriage cries made by the males, the cries of protection of the territory produced by the males and females together and apart. The liberation cry makes both sexes when crumbling errors happen. Finally, the scream of danger is emitting both gender.
As showed observations of Berlandieri and R. Sphenocephala in Texas, vocalization does not serve as the only factor of ovulation, and acts along with temperature and humidity conditions and contributes to the synchronization of ovulation within the species in the period most favorable for reproduction.
The level of sound activity of pond and lake frogs is determined by the weather of the same preceding day. If during this period there was cloudy weather, the frogs are silent. But after some two warm days, they start singing again. The lower temperature limit of water, in which the frogs feed the voices, 12 ° C.
The dependence of vocalization from abiotic factors was also investigated by garlic, herbal, butterproof and pond frogs. It turned out that the illumination suppresses sound activity, and the increase in temperature in certain limits contributes to its increase.
Amphibians typically lay a large number of eggs calculated by thousands. Those of them who are peculiar to the internal fertilization or care of the offspring are put significantly less eggs. Their eggs are distinguished by large size due to the increase in the supply of nutrients in the yolk.
Where the weather does not change markedly for the seasons, the reproduction of amphibians continues all year round. In other areas, it is timed to the most favorable time of the year, when optimal temperatures and larva conditions can be provided with food. In a temperate zone, ground species multiply aqueous, as they differ in greater resistance to low temperatures; The ability to maintain activity at relatively low temperatures is developing from terrestrial species due to the fact that they are forced to fade into the most wet time of the day, which is usually the most cold.
In addition to early breeding, it is characterized by a reduction in the timing of the ikrometania, the development of eggs and larvae. This leads to the fact that they are neither adult state, nor in the larvae do not face or almost do not face water bodies with vody, avoiding competing. Reducing the timing of development and reproduction allows ferments to fly by land over long distances and use rapidly drying time reservoirs for the development.
The growth rate and development of tadpoles depends on the temperature and on the interaction of them between themselves. The latter is carried out through the products of vital activity (metabolites) of headastrics entering water. The saturation of water products of vital activity increases with an increase in the number of tadpoles in the reservoir.
In experiments, it is shown that this leads to the braking of their growth in the first period of their embryonic development. Then there comes actually complete cessation of growth and death of part of animals. The surviving headastrics resume growth and finish metamorphosis with significantly smaller body sizes. The resumption of growth and development of survivors is associated with a decrease in the number of metabolites entering water, as well as with a decrease in food competition.
Vital products have a high specificity of action. Metabolites of the headastrics of late stages of development inhibit the development of small individuals; Small individuals do not have a significant impact on the development of large or accelerate it. Metabolites possess the greatest action on the headastrics of the same masonry and to a lesser extent on individuals from other masonry. Due to this, the diversity of all ponds is maintained.
In natural conditions, the influence of the larvae of a herbal frog was experimentally studied, first in the season starting to reproduction, on the rate of growth and development of larvae of pond and a core frog. It is shown that the larvae of herbal frogs, which are in the reservoirs of physiologically older than the larvae of the pond and crooking frogs, inhibit the growth and development of the latter. The manifestation of this effect is enhanced with the increase in their cluster, often leading to the complete extinction of the larvae of the retained species.
Interesting observations were held on the headastrics of Rana Hechscheri from the USA. The casuals of this species are large, brightly painted, form long-saving clusters. The laboratory shows the negative reaction of these tadpoles into the light. The desire of isolated talkers to sail into the shadow in nature leads to the fact that it floats into the shadow created by the accumulation of tadpoles. This contributes to maintaining a cluster. Feeling food or water with the smell of feed, the tadpoles took power pose. The same pose took the neighboring tadpoles, placed in another vessel, who saw food, but could not feel his smell. Water with a smell of a person or wounded ovens caused the response of flight.
Among the amphibians there are forms, the development of which is not fully connected or not at all is associated with the reservoir. This feature arose independently (convergent) in all three detachments and is accompanied by "care for offspring." The most often terrestrial development is found in the tropics, due to the peculiarities of the oxygen regime of reservoirs.
Small freshwater tropical reservoirs are extremely poor oxygen due to high temperatures and a huge number of rotting organic residues. In addition, they are excessively saturated with alive creatures. The reason for the transition to terrestrial development can also serve as low water temperature, a strong flow and absence of water bodies.
Development can occur outside the water completely or only to the stage of the larva. In the tropics for this, temporary accumulations of rainwater are used, for example, in the interstices of plants or in rotten stumps and dupes. Amphibians lay eggs and in wet places on the shore of the reservoir, on plants in water, in the cracks of rocks and other similar places.
In some cases, parents themselves are digging or satisfied with the foam mass of the nest, which are placed in both water and in the soil and on plants. So, many quaches and philomases are placed over the water. Females of philomaouus, arranging nests, hold the rear paws the frontal edges of the leaves and lay the eggs in the resulting tube, whose shell glue the edges of the leaves (Fig. 26, 2, 3).
The humidity required for the development of the embryo can be maintained and thanks to the constant contact of masonry with a body of one of the parents. For example, Ceylon worm wreck the masonry of the eggs in Nore.
Developing eggs can be inserted by amphibians in special formations on the body of parents, like the svacchas and Suriname Pips. Rinoderma Darwin is shears developing eggs in a voice bag, the Australian Water Frog Rheobatrachus Silus Female swallows fertilized eggs or larvae in the early stages of development, and then shelters them in the stomach until the completion of the metamorphosis, after which young frogs appear through the mouth. Some amphibians are characterized by a legability. For example, among those barking, it is known for the desert African toad genus Nectophrynoides. Recently, the ability has been found in the newly described type of woody frog from Puerto Rico - Eleutherodatylus Jasperi. .
Life of animals. In 7 tons / ch. ed. V. E. Sokolov. T. 5. Amphibian. Refreshing / A. G. Bannikov, I. S. Durirevsky, M. N. Denisova et al.; Ed. A. G. Bannikova. -2-E ed., Pererab.-M.: Education, 1985.-399С., Il., 32 liters. Il.Aof | 03/07/2018 18:27:30
The separation system is represented by a pairPrimary torso kidney
From the blood passing along the kidney vessels, unnecessary organism of the substance is filtered and urine is formed. From kidney inUreterals
Water falls in
and from it enters Cloaca .
. From a filled bladder urine flows into a clock, and then removed outward. Pay attention! Deployed end product of nitrogen exchange in amphibians -
urea Reproduction and development of amphibians occurs in water
. Parry seeds and ovaries. Fertilization most often outdoor. Development with metamorphosis. Females sweep into the water Icra , very similar to caviar of fish, and males watered it with seed liquid. Spermatozoa penetrate the eggs and fertilize them. Irkin shells in water swell greatly, made transparent, glued together with each other, forming lumps, and float onto the surface or attached to underwater objects. After fertilization Larvae begin to develop rapidly, as a result in Ikrinka Forms multicellular germin . A few days later, the eggs appear Larva - Golovastik .
. The headastrian first has a tail and reminds Fish Fish. Blowing the headasting gills located on the sides of the head. He has, like fish,
Two-chamber heart and one circle circulation
In further development
Easy, three-chamber hearts appear, two circle of blood circulation
. The rear and forefinders appear, it is sophisticated, shortening, and then the tail completely disappears, and the headasting turns into a small frog.
Biology. Animals. 7 CL: student. For general education. institutions / V. V. Latushin, V. A. Shapkin. - M.: Drop.
Tritek D. I., Sumothein S. V. Biology. Animals. 7th grade. - M.: Mnemozin.
Nikashov A. I., Sharov I. Kh. Biology. Animals. 7th grade. - M.: Vlados.
Konstantinov V. M., Babenko V. G., Kuchmenko B. C. / Ed. Konstantinova V. M. Biology. 7th grade. - Publishing center of Ventana Graf.
Who are such amphibians?
Amphibia, or amphibians (amphibia) - cold-blooded four-legged vertebrates, whose eggs do not have a tight protective sheath around the embryo. The term "amphibian" comes from Greek AMPI meaning "both" and "bios", which means "life", therefore, "double life". This reflects the fact that most amphibians are two-phase, have an aqueous stage, where they spend part of their time, as well as ground stage. Many, but not all amphibians, are undergoing changes from the aquatic larch stage, in which they use oxygen from the water and lack the limbs to four-legged, breathable by air, adult individuals adapted to life on Earth. There are about six thousand different living species of amphibians. Examples include frogs, toads, salamanders, tritons, proteins and worms.
Photo Julian Hodgson Flickr.com
A very diverse group of animals that poorly illustrates the most common determining characteristics, amphibians usually have smooth and naked skin. Nevertheless, some of them have dermal scales. Compared to the fish, the terresth the aqueous phase is usually breathing through the skin and through the lungs, and not due to the gills, and have limbs instead of fins, but some amphibians also use gills. .
Having habitat in most areas of the world, amphibians play an important role in the balance sheet of nature. They illustrate two-level functionality, since they consume a significant amount of insects and other invertebrates and themselves are victims of large animals, which makes them an integral part of food networks. Amphibians are also important in the circuit of nutrients and as precondigursors of harmful environmental changes.
Amphibians also play an important role in human society. And historically, and currently substances produced from amphibians are an important source for medical preparations. It is proved that they reduce the prevalence of diseases caused by insects, due to the reduction of their number. In the religion of amphibians, they were often important symbols, whether in shamanismé, early Egyptian religions or religions in Pontolombian America. Since the 1970s, many populations of amphibians began to decline, and a significant part of the reduction is explained by anthropomorphic (caused by humans) by the reasons. Both ethical and practical considerations, people need to invest in the preservation of these valuable animals. The study of amphibians and reptiles is known as herpetology Features of amphibians Most amphibians produce eggs without shells or membranes (
), which are deposited in water and rely on moisture from the environment. Adult amphibians have a three-chamber heart (
Larvae have a two-chamber heart
) And usually two lungs. They have two protrusions on the back of the skull (occipital sodes), while reptiles have only one occipital sumout.
- Photo Grim Fandango Flickr.com Although most amphibians lack fixtures necessary for completely earthly existence, some of them are actually completely earthly, even born on land; Others may require an exclusively wet habitat. Some of them are completely water. Being cold-blooded organisms, many amphibians enter the state of rest, which is known, in adverse conditions (cold winter), as a winter hibernation, and during drought (in summer), as an estimate.
- Classification and variety of amphibians All amphibians belong to Amphibia Class Vertebrata (Vertebrata). All existing amphibians are accommodated in one subclass tanning (Lissamphibia). The subclass is three detachments:
- Detachment Children's Funny (Anura - Frogs and Toads) : 5,602 species in 48 families;
Detachment Tailed amphibians (Caudata or Urodela - Salamandras, Tritons, Protees, Sirens and Amphives)
: 571 View of 10 families;
Detachment Ruthless Amphibian (Gymnophiona or Apoda - Covers) : 190 species in 10 families.
Frogs and toads differ from other types of amphibious presence of larger hind limbs among four limbs. Adults have no tails. Frogs and toads are the most numerous and varied amphibians, which are found in almost all seats of habitat, including in aboral, water and earth niches and every continent, with the exception of Antarctica. Three species have aroles extending over the polar circle. Paperless amphibians have well-developed voices, while the two other detachments of amphibians are limited only by sounds as cough and grunts.
Reproduction and development of amphibians
Salamandras, Tritons, proteins, sirens and amphiums are members of the detachment of tailed amphibians, respectively, all of them have tails. As a rule, all types of detachment have similar limb sizes, but amphihium reduced limbs, and the sirens do not have the hind limbs and reduced front limbs. The biggest amphibian in the world is a taper, the Chinese giant salamander, which can reach two meters, and her close relative is the Japanese giant salamander, grows up to 1.6 meters. Salamandras are most numerous and diverse in temperate zones.
Very similar to ordinary worms, they lack external limbs. The heads of these amphibians are adapted for digging, their skull is strongly inflated. The worms are also the only ammunition with dermal scales, they look more like fish, than reptiles. Urban amphibians have a unique sense body that retains the tentacle, discovered between the nostrils and the eye, which acts as a chemical sensor. The worms live under the ground, most of them have small eyes, they are poorly known to science and many do not even have common names. There are about 200 famous worm species. They are found only in the tropical and subtropical regions of the world. Amphibians have dimensions from a few millimeters to those mentioned above the two-meter salamander. Amphibians have mastered almost every climate on Earth from the hottest deserts to the frozen land of the Arctic. They are located in almost every environment where there are fresh water during the year. Indeed, some toads survive in the deserts in underground badges arising only during periodic, heavy rains. External and internal reproduction is known among amphibians. Paperless amphibians use mainly external fertilization, while Salamandras and worms are internal.
Photo Yakovlev.Alexey Flickr.com.
For reproduction, most amphibians need fresh water. Several species use and bracking water, but
There are no real marine amphibians
. However, several hundred species of frogs are not needed in any water. They breed through direct development, adaptation, which allowed them to be completely independent of the water. Almost all these frogs live in wet rainforests, and miniature versions of adult individuals are hatched from their eggs, completely bypassing the staging of the larval headstuff. Several species are also adapted to the arid and semi-sore environment, but for most of them, water is still required to lay eggs. Symbiosis with single cellular algae, which live in a jelly-shaped layer of eggs, is present in a number of species.
Nevertheless, most amphibians pass both the aqueous stage and ground. Amamniotic (without a shell) eggs are laid in water. After hatching of the larva, amphibians breathe by external gills. Many begin to gradually externally transform into an adult person through a process called metamorphosis. For example, frog larvae (casuals) gradually absorb their tail and develop legs for walking on land. Then the animals leave the water and become earthly adults.
While the most obvious part of the amphibian metamorphosis is the formation of four legs to support the body on land, there are a number of other major changes: the gills are replaced by other respiratory authorities, that is, light; The skin changes and develops glands to avoid dehydration; Eyes acquire eyelids and adapt to vision outside the water; For the blocking of the middle ear, a drummeal appears; The heart becomes three-chamber; The frogs and the toad disappears the tail.
The ability of some tadpoles to regenerate lost parts of the body (such as tail or foot) usually disappears during metamorphosis. Nevertheless, many salamanders retain the ability throughout their lives to regenerate a wide variety of fabrics and structures, such as muscles, cartilage, skin, spinal cord, parts of the eyes and jaws.
While in many species of amphibians, newly hatched aqueous larvae is subjected to metamorphosis in adulthood, there are many exceptions for this method of development. Many larvae of Salamander are similar to minors and adults, with the exception of water signs, such as gills. Some amphibians develop without a larval form, with young, hatching directly from the egg. In addition, although many types are quickly turning in adults, some larvae remain aquatic for months, even years, until the appropriate conditions arise. Paleomorphism is the preservation of the characteristics of the larvae in hawk animals, and this is characteristic of many types of tailed.
When a typical two-phase species returns to breeding water, some tailed, which spend a lot of time in water, is subjected to second metamorphosis, resulting in adaptation to a water lifestyle.
Amphibians directly depend on seasonal changes in nature. Therefore, the cycle of their life includes periods: spring awakening, reproduction (spawning), summer activity and wintering.
In summer, amphibians lead active lifestyles, accumulate nutrient reserves. In the fall with a decrease in ambient temperature, their activity is gradually decreasing, they become low-loving. Amphibians begin to prepare for wintering and are looking suitable for this place. Green frogs winter on the bottom of the same reservoirs where they were in the summer. Many other frogs are wintering both under water and on land, and Tritons, inhabitants in the summer in reservoirs, winter on land. For wintering on land, amphibians choose pits filled with foliage, rodent holes, basements, cellar, drunk logs, etc. On land, amphibians may suffer and even die from the effects of very low temperatures, and in water, where the low temperature is not as dangerous, they sometimes suffer from lack of oxygen.
Meaning and preservation of amphibians
Amphibians are important for ecology and people. In particular, adult amphibians are significant insect consumers, as well as other invertebrates and some vertebrate animals. Larching amphibians are also powered by insects, algae and zooplankton in the aquatic environment. On the other hand, they themselves are sources of food for fish, birds, mammals, reptiles and other amphibians. Thus, they play an important role in food networks. The loss of adult amphibians is often associated with an increase in the number of insects, and the disappearance of the larvae can lead to the flowering of algae, the low level of oxygen and due to the death of fish. Controlling insects, amphibians also help reduce the threat of diseases transmitted by insects.
Amphibian toxins, which vary from moderately harmful to death, are often harmless to people and are widely used in medicine. Today, amphibians help to fight with bacterial infections, skin cancer and colon, depression and many other diseases.
Amphibians play an important role in human culture and religion. In addition to their historical use in folk medicine, amphibians were widely represented as evil creatures (probably to some extent, from their often nightlife), or as indicators of good luck, fertility and rain. Shamans, spiritual leaders in the religion of shamanism, used them as religious symbols and in the creation of hallucinogenic drugs.
In some cultures, including early Asian and Precucumbian American civilizations, the toad was considered divine, the source and end of all his life. In Egypt, the goddess of childbirth, hecks, depicted from a frog head, and objects with frog figures are placed in the Egyptian tombs to reflect the demons from the underground world. In some other cultures, the frogs and toads had less positive connotations associated with witch and their boilers. In Guatemala, there are bizarre myths about night salamander, which climb babies and cause them a sudden death.
Since the 1970s, a sharp decline in amphibious populations began, but only about one percent of the types of amphibians from their total amounts have experienced a global decline. Many of the reasons for their reduction remain insufficient, and are currently subject to perennial research.
Modern fauna of amphibians, or amphibians, is not small - less than 2 thousand species. Throughout life or at least in a larval state, amphibians are necessarily associated with an aquatic environment, since their eggs are deprived of shells that protect the drier action. Adult forms for normal livelihoods need constant moistening of the skin, so only inhabit the reservoirs or in places with high humidity. Amphibians in morphological and biological features occupy an intermediate position between actually aquatic and actually terrestrial organisms.
The origin of amphibians is associated with a number of aromorphosis, such as the appearance of a five-palpal limb, the development of the lungs, the separation of the atrium into two chambers and the emergence of two circles of blood circulation, the progressive development of the central nervous system and sense organs.
Frog - a typical representative of amphibians
Frog - amphibian (non-reptile) , a typical representative of the Amphibian class, on the example of which is usually given a class characteristic. A frog has a short torso without a tail, elongated hind limbs with swimming pools. The forelimbs, unlike the rear, have significantly smaller dimensions; They are four fingers instead of five.
The structure of amphibians Skeleton and muscles
Amphibian body cover
. The skin is naked and always covered with mucus, thanks to a large number of mucous multice glazed glands. It performs not only a protective function and perceives external irritation, but also participates in gas exchange.
. The spinal column other than the torso and tail departments for the first time in the evolution of animals, cervical and sacral departments appear. The cervical department has only one ring-shaped vertebra. Then follows 7 torso vertebrae with side processes. In the sacral division, too, one vertebra, to which the bones of the pelvis are characterized. The head of the frog is represented by Wrostil - the formation consisting of 12 talented vertebrae. Between the bodies of the vertebrae, the remains of chord are preserved, there are upper arcs and a faint process. There are no ribs and chest amphibians.
In the skull, significant carbage remains remained, which causes the similarity of amphibians with cyzerfisces. The skeleton of free extremities is dismembered by 3 departments. The limbs are associated with the vertebral post through the bones of the belts of the limbs. The front limb belt includes: yard, two ravene bones, two clavies and two blades. The belt of the hind limbs is represented by the accrete pelvic bones.
. Skeletal frog muscles can ensure the movement of body parts due to the reduction. The muscles can be divided into groups of antagonists: flexors and extensors, leading and discharge. Most muscles are attached to the bones of tendons.
Digestive system of amphibians In the mouth of the frog, there is a language that is attached to its forefront and animals thrown it when catching mining. On the upper jaw frogs, as well as in the sky bones there are undifferentiated teeth, in which the resemblance to fish is manifested. Salus does not contain enzymes.
The digestive channel, starting with the rotoglota cavity, turns into a throat, then into the esophagus and, finally, in the stomach that goes into the guts. The duodenum lies under the stomach, and the rest of the intestines are arched with hinges, then go to the rear (straight) intestine and ends with a clock. There are digestive glands: salivary, pancreas and liver.
The digestive system of amphibians
Separational system of amphibians
. Dissenlation products are allocated through the skin and light, but most of them are highlighted by the kidneys. From the kidneys along the ureters urine is displayed in a clock. For some time, urine can accumulate in the bladder, which is located at the abdominal surface of the Cloaca and has a connection with it.
Amphibians breathe both light and skin.
Light are represented by thin-walled bags with a cellular inner surface. The air is pumped into the lungs as a result of the injection movements of the bottom of the rotoglota cavity. With a diving frog, air filled with air filled with the role of a hydrostatic organ.
- Speed-shaped cartilage appear, surrounding the Gundy slit and the voice ligaments stretched on them, are available only in males. Strengthening sound is achieved by voice bags formed by the mucous membrane of the oral cavity.
- Amphibian respiratory system
- Blood system of amphibians
The heart is three-chamber, consists of two atrial and ventricle. Alternately, both at the sortia are reduced, then the ventricle. In the left atrium, blood is arterial, in the right - venous. In the ventricle, blood is partially mixed, but the structure of blood vessels is such that:
The brain gets arterial blood;
In the whole body, the blood comes mixed.
Amphibians have two circle of blood circulation.
Venous blood in the lungs and skin is oxidized and enters into the left atrium, i.e. A small circle of blood circulation appeared. From the whole body, venous blood enters the right atrium.
Amphibian circulatory system
Thus, the amphibians have formed two circle of blood circulation. But since the mixed blood is mainly incredible into body organs, the intensity of metabolism remains (as well as fish) is low and the body temperature differs from the environment.
Reproduction of amphibians
The nervous system of amphibians consists of the same departments as fish, but in comparison with them has a number of progressive features: greater development of the front brain, the full separation of its hemispheres. 10 pairs of nerves come out of the brain. The appearance of amphibians, accompanied by a habitat and out of water to land, was associated with significant changes in the structure of the senses. The eye appeared blurred lens and convex cornea, adapted to the vision on a fairly distant distance. The presence of eyelids protecting the eyes from the drier action of air, and the blinking meal point to the similarity in the structure of the eye of amphibians with the eyes of real land vertebrates.
Nervous amphibian system In the structure of the hearing authorities, the development of the middle ear is of interest. The outer cavity of the middle ear is closed by the drummeal, adapted to the capture of sound waves, and the inner cavity is the Eustachiev pipe opening into the throat. In the middle ear there is a hearing bone - stirring. There are external and internal nostrils in the sense of smell. The body of taste is represented by taste kidneys in the language, sky and jaws.
In the frogs expressed a sexual dimorphism
- . Distinctive signs of males are tubercles on the inner finger of the front legs and voice bags (resonators). Resonators enhance sound when squabbing. The voice first appears in amphibians: it is related, obviously with life on land.
- The development of a frog, as in other amphibians, occurs with metamorphosis. Larms of amphibians are typical water inhabitants, which is a reflection of the lifestyle of ancestors.
Amphibian development, on the example of the frog
- To the peculiarities of morphology, talkers having an adaptive value in accordance with the conditions of habitat are:
- Special apparatus on the bottom side of the head, which serves to attach headstoves to underwater subjects;
- longer than an adult frog, intestine (compared to body sizes). This is due to the fact that the headasting consumes vegetable, and not an animal (as an adult frog) food.
- The features of the organization's headstuffs that repeat the signs of ancestors should be recognized as a fishery shape with a long tailflower, the absence of five-way limbs, outdoor gills, side line and one circle circulation. In the process of metamorphosis, all organ systems are rebuilt:
- Grow limbs;
Zabras and tail are cut;
The nature of the food and chemistry of digestion, the structure of the jaws and the whole skull, the skin;
The transition from gill breathing to the pulmonary, deep transformations occur in the circulatory system system.
- The rate of development of tadpoles depends on temperature: the hotter, the more faster. Usually, the turning tower in the frog is required for 2-3 months.
- Mature of amphibians
Currently, the class of amphibians include 3 detachments: Tailed;
У taught; Ruthless.
Tailed amphibians (Tritons, Salamandras, etc.) are characterized by an elongated tail and pair short limbs. This is the least specialized forms. Little eyes, unaware. Some of some life saves gills and gill gaps. Chisty amphibians
(Toad, frogs) The body is short, without a tail, with long rear limbs. Among them there are a number of species that are used in food.
To the detachment
Conditions are inhabited in tropical countries. Their body is drawn, devoid of limbs. Feed worms with rotting plant residues.
On the territory of Ukraine and the Russian Federation, the largest of European frogs - the frog of the lake, the length of which reaches 17cm, and one of the smallest chickened amphibians - ordinary quix, having a length of 3.5-4.5 cm. Adult quanks usually live on trees and have special discs at the ends of the fingers to attach to the branches.
- Four kinds of amphibians are listed in the Red Book: Triton Karpathian, Triton Mountain, Toad, reed, frog is angry.
- The origin of amphibians
- Amphibians include forms whose ancestors are about 300 million. Years ago left the water to land and adapted to new terrestrial living conditions. From fish, they were distinguished by the presence of a five-plated limb, lungs and related characteristics of the circulatory system.
- With fish, they were united:
- Development of larvae (headstuffs) in aquatic environment;
The presence of the larvae of gill cracks;
the presence of a side line;
The absence of germinal shells during embryonic development.
The ancestors of amphibians among the ancient animals are counted by cyzer fish.