What are amphibians? Detailed answer

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What are amphibians? Detailed answer

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What are amphibians?

Another name for amphibians - amphibians - comes from a Greek word meaning "living a double life." Most amphibians spend the initial part of their life in water, and then move to land. There are three groups or orders of amphibians: frogs, salamanders and caecilians. Various types of newts belong to salamanders. Worms are creatures that live in burrows. They are blind and have no legs or tail. There are more than 1040 species of amphibians. All of them do not reach a meter in length, with the exception of a giant salamander living in Japan, which can grow up to 1,5 m.

Most amphibians do not differ in strength or speed of movement, although frogs can move quite quickly. Most of them are protected by a tendency to solitude and inconspicuous coloring. In addition, almost all amphibians are capable of producing toxic substances with their skin glands, and this serves them as the best defense against enemies.

As adults, most amphibians have lungs, but they also breathe through their skin. Amphibians are usually found only in areas with a hot and temperate climate. As a rule, they do not live in salt water. Although adult amphibians usually live on land, they may return to the water during the breeding season. Here they lay their eggs, and here the young generation spends the initial period of their life in the form of tadpoles, feeding mainly on plant foods.

Some amphibians have rather strange methods of caring for their eggs. A female tree frog from Brazil builds a mud nest for her eggs while the male sits and croaks. The Suriname toad carries its eggs on its back. Amphibians that leave their eggs unprotected in the water usually lay hundreds of them at once, bonding them into strips or heaps with a sticky substance. Those who take care of their offspring lay fewer eggs.

Author: Likum A.

Random interesting fact from the Great Encyclopedia:

Who discovered atoms?

The idea of an atom as the smallest particle of any substance originated with the ancient Greeks. Today we know that an atom is not the smallest particle, that there are smaller particles that are inside the atom itself. We also know that we do not know everything about the structure of the atom.

The first person to develop the scientific theory of the atom was John Dalton, an English chemist who lived in the early XNUMXth century. He discovered that gases, like solids and liquids, are made up of incredibly tiny particles. He, like the ancient Greeks, called these particles atoms. He determined the relative weights of the atoms of those elements that were familiar to him. At the end of the XNUMXth century, Ernest Rutherford developed the theory of the atom, believing that it was similar in structure to the solar system. He suggested that in the center of the atom there is a nucleus, it is heavy and carries a positive electric charge. And around it are negatively charged electrons. Electrons move around the nucleus in the same way that planets move around the sun.

Later, Niels Bohr created a new atomic theory. He proved that electrons can only move in certain orbits called energy levels. When an electron moves from one level to another, it changes its energy. But human knowledge of the structure of the atom is constantly changing as new experiments provide new information.

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Good cholesterol protects the liver from inflammation 30.07.2021

"Good" and "bad" cholesterol are called different types of lipoprotein particles - large transport complexes of lipids and proteins. "Bad cholesterol", that is, low-density lipoproteins (LDL, or LDL), are bad because they increase the likelihood of atherosclerosis: lipids from such particles tend to accumulate in the walls of blood vessels, contributing to the formation of atherosclerotic plaques. "Good cholesterol", that is, high-density lipoproteins (HDL, or HDL), are good in that they do not increase the likelihood of atherosclerosis. At the same time, it is believed that it is best when both "bad" and "good" cholesterol float in the blood less.

However, both low and high density lipoproteins have varieties. And among the "good cholesterol" there are particles called HDL3, which are good for the liver. The fact is that from time to time bacterial lipopolyscharide, fragments of the cell wall of bacteria living in the intestine, enters the liver. These bacterial fragments cause immune cells to react, and a flaccid inflammation begins in the liver. And as you know, inflammation harms not only infections, but also healthy tissues; due to inflammation, healthy cells die, they are replaced by connective tissue, and as a result, the organ no longer functions as well as it should.

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Molecular complexes of HDL3 and LBP are also formed in humans, which means that the same mechanism of protection of the liver can work in us. If this is the case, then it remains only to develop HDL3-enhancing drugs for humans - such drugs could be a good remedy for various liver diseases associated with inflammatory processes.

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