What is the simplest?
Watch the video
Life on Earth originated many millions of years ago. And it originated from the simplest organisms. They represented (and to this day are) just one cell, which, however, became the progenitor of all living beings. Consider what the simplest.
Origin of life
Scientists believe that life on our planet originated more than 3 billion years ago, when the simplest organisms appeared in the sea. How exactly they arose, at the moment science is not known. According to a common hypothesis, protozoa appeared as a result of chemical reactions that occurred in the atmosphere and oceans. However, there is a theory that the simplest organisms were on Earth as a result of a meteorite falling. Also does not exclude the possibility of alien origin of the simplest.
Now there are over thirty thousand species of a variety of single-celled. Some are found in freshwater, marine environment, soil. Many protozoa also live in the body of many animals and humans.
As a rule, unicellular organisms are a microscopic body. Only rare specimens can reach lengths of a few millimeters. Despite the fact that the protozoa are in essence only one cell, they can be called an integral organism, which is divided into two main parts: the nucleus and the shell. The world of single-celled is so diverse that it is studied to this day. At the moment, there are several groups and classes of unicellular organisms.
Groups and classes
Consider the main groups and classes of the simplest.
The simplest with a non-permanent body shape
The first group is the protozoa with a non-permanent body shape. They are called that because their plasma membrane is extremely thin. These single-celled are called rootlets. These single-celled mostly found in the sea. ATat the same time, they can live in the human body. It is believed that they are the simplest parasites, but one cannot say that these single-celled cells are capable of causing any harm to the body, since their influence on it is extremely small, even if they are found in large quantities.
Separate class of this group decided to allocate amoeba. This representative single-celled with a non-permanent body shape looks like a colorless tangle. It is found mainly in fresh water. Amoebas feed on a variety of bacteria or algae. A characteristic feature of the amoeba is reproduction by division.
The simplest with a constant body shape
The next group of unicellular organisms are those with a constant body shape. TOThese include infusoria. A characteristic feature of ciliates is the presence of two nuclei, each of which performs a different function. Also, unlike the same amoeba, the ciliate has cilia that allow it to move. In the case of amoeba, the movement is carried out at the expense of the paws - protrusion of the cytoplasm. The diet of ciliates includes bacteria, algae, dead organic matter. Ciliates multiply by division.
The simplest with an elastic shell of the body
The next group of unicellular organisms are protozoa with elastic shell of the body. The elastic shell determines the shape of the simplest. These protozoa mostly have one core. A representative of such protozoa is Euglena green.This species lives in freshwater bodies. This environment is very favorable for euglena. Due to the elastic shape of the body, it can quickly move in fresh water. The movement of this simplest is carried out at the expense of a single flagellum, which acts as an unwinding mover. The mechanism of movement resembles the movement of a torpedo. Euglena green feeds on bacteria, algae. Reproduction occurs by division. And in favorableUnder conditions of this, the simplest can multiply every day.
A separate class can be distinguished protozoan parasites. As we said above, some of them are absolutely not dangerous for the body. However, there are those that pose a real threat to life and health. These include sporozoviki. Among them are the simplest called malarial plasmodia. It is them that the anopheles mosquitoes carry in their saliva. Getting into the blood, these parasites rush to the liver, where they actively proliferate. Next, they capture the cells-erythrocytes. This leads to further destruction of blood cells.
The parasites include infusoria, which have managed to adapt to life in the intestines of animals.They can also harm the body by causing inflammation.
The variety of the simplest proves that the microcosm is rich in species as well as the macrocosm. And it is his study that helps to understand how life appeared on the planet.