Classification of living organisms

Classification of living things

Organisms are classified into major groups according to basic and common characteristics among organisms, and these characteristics include appearance, reproduction, mobility, and function. The snake is divided into 7 levels: kingdom, phylum, caste, order, family, genus, and species, and the following is a detailed explanation of each level:

The kingdom

At first, organisms were classified into two kingdoms only; The animal kingdom includes moving organisms that eat and grow for a while, then stop growing, and the plant kingdom includes stationary organisms that do not eat and grow throughout life. Organisms are divided into 5 kingdoms, and they are classified according to common characteristics, which are as follows:

  • Nutrition: Autotrophs that produce their own food, or heterotrophs that feed on other organisms.
  • Organization of cells: single-celled organisms that contain only one cell, or multicellular organisms that contain two or more cells.
  • Cell Type: Eukaryotic cells contain a membrane-enclosed nucleus, or prokaryotes are organisms that lack a membrane.
  • Respiration: Organisms that need oxygen and breathe aerobic, and organisms that do not need oxygen and breathe anaerobic.
  • Reproduction: sexual reproduction, asexual reproduction, or reproduction by spores.
  • Motion: Self-moving objects or stationary objects.

Organisms are classified into 5 kingdoms: Animal kingdom The animal kingdom consists of two groups; Vertebrates and invertebrates, including mammals, fish, birds, reptiles, amphibians, insects, molluscs, worms, etc. Plant kingdom The plant kingdom or the Plantae kingdom is one of the oldest kingdoms and includes trees and other types of plants, and they share that they are fixed, multicellular and eukaryotic organisms, some of which reproduce sexually and some are asexual, and they are autotrophic, and they carry out the process of photosynthesis that releases the oxygen necessary for life . Fungi kingdom The fungi kingdom includes all types of mushrooms, frogs, yeasts, and molds. They are non-autotrophic and reproduce by spores. They are non-eukaryotic multicellular organisms, and their cell walls contain chitin. Protista kingdom The kingdom of protists includes the most primitive organisms of eukaryotes, and it also includes eukaryotic organisms that do not belong to the kingdom of animals, plants, or fungi such as protozoa, some of which are very small and some large that can be seen with a magnifying glass or a dissecting microscope, moving through cilia, flagella, or mechanisms Amoeboids obtain their food through photosynthesis, by feeding on organisms by swallowing, or through a combination of both processes. Monera kingdom Kingdom Monera includes microscopic organisms such as archaea and bacteria, which are prokaryotes, consisting of a single cell without a nucleus.


The phylum level (in English: Phylum) classifies living organisms into groups according to their common features, and in the animal kingdom there are phyla called “chordates”, which include all animals that have a backbone, and humans fall into these phyla because they have a backbone, and the phylum level is divided into several sections Which:

  • Phylum Porifera: includes sponges.
  • Phylum Coelenterata: includes jellyfish, hydra, and corals.
  • Phylum Flatworms: Includes flatworms.
  • Phylum Nematoda: includes roundworms.
  • Division of annelids or leeches (in English: Annelida): includes segmented worms.
  • Arthropoda phylum: includes insects.
  • Molluscs: includes shellfish.
  • Phylum Echinodermata: includes sea urchins.
  • Phylum Chordata: includes chordates.


The class level comes below the division level. The animal kingdom includes approximately 108 classes, including the class of mammals, reptiles, modern birds (aves), and many others, and the class of arthropods includes insects, spiders, mites, and scorpions. The sect level comes above the rank level and below the division level, for example; The Chordata phylum includes the mammalian class, while the mammalian class includes several different orders, such as bats, monkeys, whales, elephants, and others.


Organisms in each class are divided into several different ranks, and the classification key is used to determine the rank of the organism. The classification key is a list of characteristics to refer to in order to determine the order of organisms and how they are divided.

She family

Orders are divided into families, so that organisms at the level of the families share more common features than any other level of classification above; They share many and detailed common denominators, and here the organisms are linked to each other, like a family.


The genus level comes between the level of the family and the level of the species, it consists of a group of species that are structurally related to each other or it consists of one species that has unusual differentiation and is called a monotypic genus, and when taxonomy is used to name an organism, the genus is used to specify the first part of its name consisting of It has two parts, and the second name uses the type level to name it. Among the examples of the genus, the Rosa plant contains 100 species of roses, while the monotypic genus Ginkgo contains only one species, which is the maidenhair tree, and the horse genus contains several types of horses and zebras.


Organisms are placed in a particular species so that organisms in a particular species are able to reproduce with other organisms of the same species, so that individuals of one species will be able to mate with each other, but each species will be reproductively or reproductively isolated from other species.

What is the importance of classifying organisms?

The importance of classifying organisms lies in several reasons, namely:

  • Identify organisms and understand their biodiversity.
  • Easily identify a wide variety of plants and animals, knowing their similarities and different characteristics.
  • Helps understand how simple organisms evolve into complex organisms.
  • Classification is a means by which we can easily deal with the great diversity of forms of living.
  • It helps in understanding the interrelationships between organisms in their broad groups.
  • Taxonomy is the basis for the development of other biological sciences.


Organisms are classified into main groups according to the basic and common characteristics between organisms, and the importance of classification lies in facilitating their study for scientists, and there are 7 major general classifications, which include thousands of different types of organisms.

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