Classification of Living Organisms, Biology tutorial


A general study of living organisms around you anywhere will disclose a broad variety of various plants and animals. These might differ in sizes, shape, color, speed of locomotion and so on. A closer study also will disclose that such varieties of forms as well show some similarities of features or behavior. We must, therefore encompass a momentous way of classifying, recognizing and naming them. The study of the general principles of categorization is termed as taxonomy or systematic.

Method of classification:

To categorize organisms into major groups, biologists look for significant characteristics which are shared by a big variety of organisms. Such characteristics must encompass a similar origin, structure and position. Organisms with certain significant characteristics in common are then put altogether into one group. Divisions and subdivisions in a major group are based on progressively less significant characteristics.

Hierarchy of Living Organism:

The biggest group of organisms is the kingdom.  The entire kingdom is divided into smaller groups and such groups into even smaller groups and so forth. The array of living organisms in this hierarchy from the highest level to the lowest is as described below:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Carnivora
  • Family: Felidae
  • Genus: Felis
  • Species: Felis domesticus

Kingdoms: The most fundamental categorization of living things is kingdoms. At present there are five kingdoms. Living things are put into several kingdoms based on how they get their food, the kinds of cells which build up their body and the number of cells they have.

Phylum: It is the subsequent level following kingdom in the categorization of living things. It is an attempt to find some kind of physical similarities among organisms within a kingdom.

Classes: These are way to further split organisms of a phylum. As you could most likely guess, organisms of a class have even more in common than such in whole phylum. Humans fit in to the Mammal Class as we drink milk as a baby.

Order: Organisms in every class are further broken down into orders. The taxonomy key is employed to find out to which order an organism fits.

Families: Orders are split into families. Organisms in a family encompass more in common than with organisms in any categorization level above it. As they share so much in common, organisms of a family are stated to be linked to one other.

Genus: This is a way to explain the generic name for an organism. The genus categorization is much specific so there are fewer organisms in each one. For this cause there are a lot of different genera between both the animals and plants.

Species: Species are as particular as you can get. This is the lowest and most strict level of categorization of living things. The key criterion for an organism to be positioned in a specific species is the capability to breed with other organisms of that similar species.

At times intermediate levels are as well added. These are generally recognized by prefixes such as sub and super, example: subphylum and super class.

Binomal Nomenclature:

We are well-known with the common names of living organisms like cat, cow, mango and maize. Biologists, though, employ a standard system to name living organisms. Each and every type of organism is given two names, therefore the word binomial nomenclature.

i) The primary name is the name of genus to which the organism fits in.

ii) The second name is the name of species to which it fits in.


In the 18th century, Carl Linnaeus proposed a system for categorizing living things, which has been build up into the modern classification system. Linnaeus was the first scientist to build up a hierarchal naming structure which conveyed information both regarding 'what the species was' (its name) and as well its nearest relatives.

Kingdoms are a manner which scientists have developed to divide all the living things. Such divisions are based on what living things encompass in common and how they distinct. This system was developed over 2000 years ago and has modified severely over the years. Presently there are five kingdoms in which all the living things are divided: Monera Kingdom, Protist Kingdom, Fungi Kingdom, Plant Kingdom and Animal Kingdom.

i) Monera Kingdom: This comprises of organisms which are made up of one cell. Such organisms are termed as unicellular. Such unicellular organisms are made up of a very simple cell which often lacks numerous cell parts, like nucleus and which are generally found in other cells.

Example: Bacteria, blue-green algae and spirochetes.

ii) Protist Kingdom: They are similar to monera in that they are unicellular. Protists are a little bit more complex as they have a nucleus. They as well encompass moving parts and can move around in their environment.

Example: Protozoan and algae of different types.

iii) Fungi Kingdom: They encompass their own kingdom as there is no other organism similar to them. Fungi can't prepare their own food.

Example: Fungus, molds, yeasts, mushrooms, mildews and smuts.

iv) Plant Kingdom: The whole plants are a part of Plant Kingdom. Plants comprise grass, trees, flowers and algae. They all share the general feature of being capable to prepare their own food by using sunlight and water.

Example: Ferns, mosses, woody and non-woody flowering plants.

v) Animal Kingdom: Organisms in the Animal Kingdom are multi-cellular and dependent on other organisms for food. This kingdom is by far the biggest among all the kingdoms. The animals of this Kingdom can found all over the world and can be any size from very tiny to very big.

Example: Worms, amphibians, insects, fish, reptiles, birds and mammals.

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