Stages of frog development, features of each stage

In this article we will consider the stages of frog development. But first let's talk a little about what kind of creatures they are. The frog belongs to the class of amphibians, the order of the anurans.

Many noticed that her neck was not expressed - she seemed to have grown together with her body. Most amphibians have a tail that the frog lacks, which, by the way, is reflected in the name of the detachment.

The frog develops in several stages, we will return to them immediately after we analyze some of the features of these creatures.

What does the frog look like?

To begin with - head. Everyone knows that the frog has rather large and expressive eyes, located on both sides of its flat skull. Frogs have eyelids, this feature is common to all terrestrial vertebrate beings. The mouth of this creature has small teeth, and slightly above it are two nostrils with small valves.

The forelimbs of the frogs are less developed than in the rear. The first have four fingers, the second - five. The space between the fingers is connected by a membrane, there are no claws.

The frog develops in several stages:

1. Calf throwing.
2. Tadpoles of an early stage.
3. Tadpoles of the late stage.
4. Adult individuals.

Fertilization is external to them - males fertilize the eggs already laid by the female. By the way, there are such species, which for one throwing lay more than 20 thousand eggs. If everything goes well, then ten days later tadpoles appear. And after 4 months of them are obtained full-fledged frogs. Three years later, a mature individual grows up, which is completely ready for reproduction.

Now a little more about each stage.

Caviar

Now we will analyze all the stages of frog development separately. Let's start from the very first - the eggs. Though these creatures live on land, during the spawning, they go into the water. Usually this happens in the spring. Masonry occurs in quiet places, at shallow depths, so that the sun can warm it. All the eggs are interconnected, and this mass resembles a jelly. From one specimen of it, one teaspoon is hardly typed. All this jelly is necessarily attached to the algae in the pond. Small species lay about 2-3 thousand eggs, large specimens - 6-8 thousand.

The egg looks like a small ball, about 1.5 mm in diameter. It is very light, has a black shell and eventually increases greatly in size. Gradually, the roe passes to the next stage of frog development - the appearance of tadpoles.

Tadpoles

After the birth of the tadpoles begin to eat yolk, which still remained in small quantities in their intestines. This is a very fragile and helpless creature. This individual has:

• Poorly developed gills;
• mouth;
• tail.

Tadpoles, in addition, are equipped with small Velcro, with which they are attached to different water objects. These Velcro are located between the mouth and the abdomen. In the attached state, the kids stay for about 10 days, after which they begin to swim and feed on algae. Gills in them gradually overgrow after 30 days of life and, in the end, completely tightened skin and disappear.

It is important to know that even tadpoles already have small teeth necessary to consume algae, and their intestine, arranged in a spiral, allows the maximum extraction of nutrients from the eaten. In addition, they have a chord, a two-chambered heart and a circulation in the form of a single circle.

Even at this stage of frog development, tadpoles can be considered quite social creatures. Many of them interact with each other like fish.

The appearance of the legs

Since we are considering the development of the frog in stages, the next step is to select tadpoles with legs. Hind legs appear much earlier than the forelegs, after about 8 weeks of development - they are still very tiny. During the same period, you can see that the head of the kids becomes more distinct. Now they can eat larger prey, for example, dead insects.

The forelimbs are just starting to form, and here we can distinguish such a feature - the first appears elbow. Only after 9-10 weeks a full-fledged frog will form, though much smaller than its mature relatives, moreover, possessing a long tail. After 12 weeks, it completely disappears. Now small frogs can go out on land. And in 3 years a mature individual will form and be able to continue its genus. This will be discussed in the next section.

Adult specimen

After three long years have passed, the frog can reproduce the offspring to light. This cycle in nature is endless.

To consolidate once again list the stages of development of the frog, the scheme will be to us in this helper:

A fertilized egg represented by an egg, - a tadpole with outer gills - a tadpole with internal gills and dermal breathing - a formed tadpole with light, limbs and a gradually disappearing tail - a frog is an adult .