American frog. Tadpoles are capable of generalizations. What happens to the tadpole of the American amazing frog as it turns into an adult animal

home So, today is Saturday, June 10, 2017, and we traditionally offer you answers to the quiz in the “Question and Answer” format. We encounter questions ranging from the simplest to the most complex. The quiz is very interesting and quite popular, we are simply helping you test your knowledge and make sure that you have chosen the correct answer out of the four proposed. And we have another question in the quiz -

• What happens to an American frog tadpole as it grows into an adult?
• A. becomes moldy
• B. decreases in size
• C. grows wings

D. changes gender

The correct answer is B - REDUCES IN SIZE

Frogs reproduce and breed in water. Their mating season begins during the rainy season. Females lay eggs among the thickets. Tadpoles reach 25 cm in length. During metamorphosis, the tadpole loses its gills, its lungs develop, its limbs grow, and its body shape changes. The tail shortens and the tadpole decreases in size daily; as a result, the adult is only 1/4 the length of the tadpole.

Hello, dear ladies and gentlemen. In this article we will discuss one of the interesting questions from today's game show "Who Wants to Be a Millionaire?"

Answers to all the questions of the game can be read in an article that will soon be published on the Sprint-Answer website. This will be an article with an overview of the game and all the questions and answers in it.

What happens to the American Wonderfrog tadpole as it grows into an adult?

The amazing frog, or Guiana water toad, is a tailless amphibian from the tree frog family that lives in South America. The name is given because of the size of the tadpoles (body length up to 25 cm), which exceed the size of an adult by 3–4 times.

• Earless tree frogs that prefer the northeast of the South American continent. Their body and head are slightly flattened. And they like to spend their free time in the trees. And in Yuzhnaya there lives an amazing frog from the tree frog family. It’s a paradox, but an adult reaches a size of only 5 centimeters, and the tadpoles grow up to 25. There is also a poisonous tree frog – the Brazilian tree frog, with blood-red spots on its back.
• decreases in size
• grows wings
• changes gender

The correct answer to the game show question is: shrinks in size.

Wood frog tadpoles are not born knowing which predators they should be afraid of and must learn this throughout their lives. Tadpoles that have been taught to fear one of the predators (the fire-bellied newt) also begin to fear other amphibians, which can be interpreted as a kind of “ability to generalize.” Moreover, the stronger the fear of newts, the wider the range of potential predators that causes a characteristic fear reaction in tadpoles.

Some animals have an innate knowledge of which predators they need to watch out for. Others are born without this knowledge and must acquire it throughout their lives. It would seem that the first option is much more reliable and safer. However, this is only true for those species of prey that live in more or less constant conditions and are threatened by the same predators from generation to generation. If the environment of a given prey species changes frequently in unpredictable ways, developing an innate fear of certain types of predators may be less beneficial than a general ability to learn—even though such learning carries enormous risks.

Many species of frogs lay their eggs in a variety of bodies of water, from small, ephemeral puddles to large lakes. In different bodies of water, tadpoles are threatened by different predators. Tadpoles react to danger by reducing their motor activity: they freeze or simply begin to swim more slowly in order to attract less attention to themselves. If a tadpole is afraid of all predators indiscriminately - including those that do not feed on tadpoles in a given reservoir - it will freeze all the time and will have less time to search for food. In such a situation, an innate fear of all types of potential enemies would be more harmful than beneficial for the tadpoles. The behavior of tadpoles (and other prey animals) must maintain a delicate balance between the magnitude of the danger and the intensity of the reaction to it. If the degree of danger posed by the same predator species varies greatly depending on conditions, lifetime learning becomes a more optimal strategy than the development of innate fear.

Little is known yet about the specific mechanisms underlying prey learning to fear predators. Of the established facts, two are the most interesting. Firstly, it has been shown that such learning occurs very quickly - usually a predator only needs to scare the prey once for it to develop a stable fear of this type of predator. In some cases, one can assume the existence of certain innate psychological “blanks” or matrices, that is, an innate predisposition to quickly develop fear of certain types of stimuli. Secondly, the phenomenon of generalization (generalization) in recognizing predators was discovered. This means that animals that have learned to fear a particular predator (in an experiment, a doll can act as a predator) often begin to experience fear also of other objects that are similar to the predator they know in appearance or smell.

In an article by Canadian biologists published on the journal’s website Behavioral Ecology and Sociobiology, interesting experiments are described in which for the first time the ability to “generalize the image of a predator” was demonstrated in the larvae of tailless amphibians.

The authors mention only three earlier studies that examined this phenomenon. If they haven't missed anything, their work is the fourth in the field. The first study was carried out on wallabies Macropus eugenii. It turned out that wallabies are not naturally afraid of foxes, cats, or goats. If you teach a wallaby to be afraid of foxes, then they automatically begin to be afraid of cats (but not goats). Another study found that wild black-tailed deer Odocoileus hemionus columbianus They are afraid not only of pumas, which pose a real threat to them in nature, but also of jaguars, which they never meet. These experiments did not use live predators, but their models, that is, they were talking about recognizing a predator only by its appearance, and not by smell or behavior.

The third study was conducted by the authors of the article discussed in 2007-2008. on a fish Pimephales promelas(black fathead, see fathead minnow). The fish were trained to fear the smell of a species of trout. It turned out that the generalization of the image of a predator occurs only if a very high degree of risk is associated with this predator. If the fish perceives this type of trout as moderately dangerous, then the smell of other types of trout does not frighten it. If the fish were made to understand that this trout was extremely dangerous, then they also began to be afraid of the smell of other trout (but not pikes or chukuchans).

In a new experiment, tadpoles of the American wood frog were chosen as the object. Rana sylvatica(see wood frog). In their previous works, the authors showed that these tadpoles do not have an innate fear of tailed amphibians (newts, salamanders), which are their natural enemies.

The wood frog eggs were placed in a large aquarium with clean water, where there were all the necessary conditions for the development of tadpoles, but there were no predators (the authors took all possible measures to ensure that there was no smell of predators there). When the tadpoles hatched and reached two weeks of age, the researchers divided them into three groups and began training. The training was carried out as follows.

Each tadpole was placed in a separate half-liter jar and allowed to get used to the new environment. Then 10 ml of water with the smell of fire-bellied newt was added to the jar Cynops pyrrhogaster. It was water from a two-liter container in which six newts lived for 24 hours. At the same time, another 5 ml of water with the “smell of danger” was added to the jar. The recipe for preparing this potion is reminiscent of the methods of medieval witches or alchemists: one tadpole was ground in a small mortar, the resulting pulp was diluted with water in an amount of 5 or 20 ml, the water was then carefully filtered to remove tissue fragments. The smell of a crushed tadpole is an unconditional frightening stimulus, that is, tadpoles from birth know that this smell signals danger.

Tadpoles from the first group received the “smell of danger” in a high concentration (1 crushed tadpole per 5 ml of water), the second group received a four times smaller dose. Finally, the tadpoles of the third (control) group received 5 ml of clean water.

The idea was that the tadpoles from the first group would associate the smell of a newt with the idea of ​​​​very great danger. The second group also had to learn to be afraid of newts, but not so much. Finally, the third group had no fear of newts at all.

The reaction of tadpoles to frightening stimuli, as already mentioned, is to slow down their movements. The authors measured the strength of this reaction as follows. A straight line was drawn on the bottom of each jar, dividing the jar in half. For four minutes before adding the scented water, the researchers counted how many times the tadpole crossed the line. If he did this less than six times in four minutes, he was excluded from the experiment. Then odors were added to the water and the number of crossings was counted again for four minutes. The ratio of the number of crossings before and after the addition of odors was used as a measure of fear.

As one would expect, during the training process, tadpoles from the first group were very afraid, those from the second group were weakly afraid, and the control group, which received only the smell of a newt, was not afraid at all.

Three days later, all tadpoles changed the water and began the main stage of the experiment. Each of the three groups of tadpoles was divided into three more parts. The first part was given the smell of a newt, the second - the smell of a tiger salamander, which is a fairly close relative of the newt, the third - the smell of an African clawed frog, which belongs to another order of amphibians.

Of these three species of potential predators, wood frogs can only encounter the tiger salamander in nature.

Tadpoles from the control group, which had not developed a fear of newts, were not afraid of any of the three odors. Tadpoles that had developed a strong fear of newts were frightened by all three smells. What frightened them most was the smell of newt, which was used during “training.” The smell of the salamander, a close relative of the newt, frightened them a little less, and the smell of the clawed frog - even less. Finally, the tadpoles, which had developed only a moderate fear of the newt, were frightened by the smells of the newt and the salamander, but remained indifferent to the smell of the clawed frog.

Thus, in tadpoles, as in fish, the degree of “generalization of the predator image” depends on the magnitude of the danger that is associated with a known predator. The greater the danger posed by a known predator, the broader the “generalizations” the prey makes. As they say, when you get burned by milk, you blow on water. A similar phenomenon was previously discovered in birds, although in that case it was not about recognition of predators by prey, but about the differentiation of poisonous and non-poisonous prey by predators (see: Unusual camouflage in frogs is associated with the ability of predators to generalize, “Elements”, 03/13/2006).

The “ability to generalize” discovered in tadpoles does not mean that tadpoles have any particularly outstanding intelligence. Conditioned reflexes, that is, reactions to certain stimuli developed during life, are always “generalized” to one degree or another. In other words, if a reflex has been developed to a specific stimulus, then another, but very similar stimulus will most likely cause the same reaction. Moreover, the more different the stimulus is from the “learned” one, the weaker the reaction will be. This property of conditioned reflexes, which is determined by the basic principles of sensory perception and the functioning of the nervous system, is, in principle, quite sufficient to explain both the phenomenon of “generalization of the image of a predator” and its dependence on the magnitude of the danger.

The American frog is an amphibian known for its large size and ability to vocalize loudly. It is native to North America, but can be found throughout Europe and Asia. The American frog lives in a variety of habitats such as lakes, ponds, swamps, slow-moving rivers and streams. People in some parts of the world hunt this frog for its tasty meat. Despite this, the American frog is far from in danger of extinction. It has a high reproduction rate and the ability to easily master new habitats. The American frog has managed to wipe out 100 native frog species through predation, competition for food, and the spread of fungal diseases. The American frog is one of the 100 most invasive species in the world.

Interesting facts about this animal:

The American frog is a fairly large frog. It can reach 3.5-6 inches in length and weigh up to 1.1 pounds. Females are much larger than males.

The American frog is usually green, olive green, brown or gray. Its skin is bumpy and covered with dark spots or stripes that provide camouflage.

The American frog has a strong, muscular body with a large head and wide mouth. The hind legs are powerful and designed for jumping. It moves easily through the water thanks to its webbed feet.

The American frog has golden eyes, a long sticky tongue, and circular eardrums on either side of its head. These organs make it easier to identify the prey and ensure a successful hunt.

Males of this frog produce a sound similar to a cow's moo during mating season. The sound produced is very loud and can be heard more than half a mile away. Males during the mating season thus attract the attention of females. The loudest singer has the highest chances of mating.

The American frog has a big appetite. Her diet depends on her age. Tadpoles are vegetarians that primarily consume algae and aquatic plants. Adults are carnivores (meat eaters). They eat various types of fish, crustaceans, mollusks, small birds and mammals.

The American frog often eats members of its own species. This phenomenon is known as cannibalism.

The American frog is active primarily at night (it is a nocturnal creature). She silently waits for a suitable prey to appear and catches it using the element of surprise (ambush predator).

The American frog has few natural enemies because its skin produces a special toxin that has an unpleasant taste. The American frog's main predators are raccoons, snakes, turtles and birds of prey.

The American frog hibernates in winter. She will remain hidden in the swamp mud until weather conditions improve.