What signs are characteristic for animals? The main signs of living organisms

Most of the multicellular living organisms that inhabit the earth are either plants or animals. It seems that the difference between them is so obvious that you can, without hesitation, determine this at first sight.

What distinguishes plants from animals

Any living organism belongs to any species, genus, family, order, and so on. At the head of the unifying categories are the kingdom of plants and the animal kingdom. Plants are able to create organic from inorganic substances in the process of photosynthesis and can not move, animals eat plants and each other and actively move in search of food.

Carl Linnaeus, the creator of the classification of the animal and plant world, defined plants as organisms that grow and live, and animals - grow, live and feel. This division no longer meets the modern requirements of science.

The qualities inherent in all living things

In order to distinguish the world of living beings in nature, it is necessary to determine which features are characteristic of all living organisms. First of all, it is a combination of the following qualities:

1. Living organisms are able to metabolize, withdraw metabolic products and in one way or another obtain the substances necessary for the continuation of life.

2. They can move or change the position of parts of the body in space.

3. Their offspring have signs of parental organisms.

4. Individuals of one species differ from each other, and the differences can be dependent and not dependent on heredity.

5. Organisms selectively react to stimuli.

6. Most of the living creatures have the ability to grow, grow.

7. During life, organisms undergo irreversible changes.

8. They can reproduce organisms like themselves.

What qualities of the living are everywhere

Many signs of living organisms, if taken separately, can be inherent in the world of inanimate nature. For example, crystals have the ability to grow, stones are very slow, but are destroyed, they can eventually move from their original location. Air, water, planets and even galaxies are moving. Conversely, plant seeds for a very long time may not show their qualities and not differ from grains of sand.

An important link connecting the world of animate and inanimate nature are viruses that are not capable of metabolism, they can be obtained in the form of crystals, dissolved and recrystallized, and they do not lose after all this inherent biological properties. Signs of living organisms - is primarily a more complex chemical composition and the presence of certain biological molecules in their structure. Special molecules of living organisms are proteins and nucleic acids.

Faking plants

In nature there are very unusual plants with atypical features, which makes it necessary to determine what signs are characteristic of animals, and what - for plants. There are plants that can not be distinguished from stones. They are similar to limestone, granite and white quartz. These plants are called lithopses. As inhabitants of deserts, they rarely receive water and are able to exist, absorbing moisture from the fog.

It is known that plants are able to react to irritation and produce substances that transmit their sensations, that plant plants produce plant hormones.

There are many plants that can not carry out photosynthesis, but receive nutrients, luring and digesting insects and small animals. Among them - sundew, venus flytrap, which preserved leaves and stems, characteristic of plants, but with other functions.

There is also a predatory plant of Rafflesia arnoldi, which has only a reddish-brown flower. The plant does not carry out photosynthesis, it does not have any parts inherent in the plant, only the structure of the cells allowed it to be attributed to this realm of living beings, and not to predatory animals.

How to distinguish plants from animals

In order to determine the belonging of certain organisms to a certain group of living beings, science must have an unambiguous answer to the question "what are the characteristics of animals, what is their difference from plants." However, it is rather difficult to give an unequivocal answer about the difference in representatives of the kingdom of plants and animals by external features.

Modern systematics is forced to conduct complex studies involving the potential of related sciences. To do this, methods are used to analyze the genetic and molecular features of this species, as well as data on their embryonic development.

Animals not similar to animals

To determine the belonging of some sea creatures to the animal kingdom, it was necessary to clarify what signs of a living organism are characteristic of animals. Scientists have needed more than one year to ensure that organisms that did not have a digestive system that lived attached to the substrate and looked like strange flowers were considered to be animals. Therefore, in order to correctly determine to which kind of living beings an unknown organism belongs, it is necessary to determine what signs are characteristic of animals.

To determine the belonging of a group of marine invertebrates to a certain type of known organisms was so difficult that it was originally decided to place them in the realm of pogonophora. These organisms in the adult state are devoid of digestive organs, and outwardly they do not resemble animals in any way. Only the study of the peculiarities of their embryonic development allowed them to be attributed to annular worms.

A characteristic characteristic only of the animal kingdom

In the animal kingdom, there are many organisms that are adapted to all kinds of habitat conditions. This changed their structure and appearance. To understand the challenges faced by zoologists dealing with the modern systematics of living organisms, list the characteristics characteristic of animals. So, in most animals:

1. There is no photosynthesis, all these organisms are heterotrophic.

2. The food enters through the mouth into the digestive cavity and is digested in specialized organs. The food is active.

3. Animal organisms are able to move. When they live on some substrate, this mode of existence is a secondary phenomenon.

4. The reaction to external stimulation happens in the form of taxis in the absence of the nervous system or reflex in its presence.

To unequivocally answer, what characteristics are characteristic for animals, it is necessary to decide what type of organisms are involved: unicellular or multicellular, chordate or vertebrate. Only for higher animals can we speak of such distinctive features as:

1. The presence of several groups of tissues: integumentary, muscular, nervous and tissues of the internal environment.

2. The presence of the following systems of organs: musculoskeletal, digestive, respiratory, excretory, genital, blood and nervous.

What is the difference between plants and animals at the microscopic level?

To give a definitive answer to the question of the difference between the representatives of the two largest kingdoms, it is necessary to determine what signs are characteristic of animals, what is their difference from plants at the cellular level.

The main features that distinguish a plant cell:

1. In plant cells, in addition to the membrane, there is a very solid cell wall consisting of cellulose.

2. Spare carbohydrates in plants are deposited as a starch polysaccharide.

3. Cells contain large vacuoles containing cell sap.

4. In the cytoplasm there are inclusions in the form of crystals of mineral salts.

5. Green plants contain plastids in cells - chloroplasts, in which photosynthesis takes place.

6. The digestive organs are absent, and the food enters the plants by osmotic pathway.

7. Reaction to external irritation in the form of tropism.

8. There is no ability for active movements.

9. When dividing cells, a constriction between them forms in the center and is distributed to the periphery.

It is also necessary to determine what signs are characteristic of animals at the cellular level.

1. The cell membrane is absent, there is a cell membrane, which is also present in plant cells.

2. The replacement polysaccharide is glycogen.

3. There are no large vacuoles in animal cells. In the simplest organisms there are small vacuoles, which perform the function of digestion or secretion.

4. Inorganic salts in animal cells, as a rule, are dissolved.

5. In animal cells there are no chloroplasts and there is no photosynthesis.

6. The constriction at cell division is formed from the edges and extends to the center of the cell.