4th Class Science Animals Classification of Animals

Classification of Animals

Category : 4th Class

*     Introduction


Every organisms living on this earth is unique in itself. This uniqueness of each living individual is the basis of the great differences or diversity of the living world. The type of living organism found in one place is entirely different from organisms found in another place. For example, animals found in plains is different from the animals found in mountains or hilly regions. In fact different places, in different part of the world have their own typical kind of living Organisms. The degree of diversity in the living world is endless.



                               Different Types of Animals

With such vast differences and large number, it is very difficult to study each and every living organism separately, at the individual level. Therefore to study and understand the life of animals effectively they have been classified into different groups, on the basis of certain criteria.


*       Classification of Animal Kingdom

The animals are broadly divided into two major groups based on the presence or absence of the major characteristic feature, that is, the back bone.


*         Invertebrates

Invertebrates are those animals which do not have a backbone or vertebral column. They are considered to be primitive form of life on the earth. A large variety of small animals like insects, worms, slugs, snail, spider and scorpion etc. belong to this group. A surprising fact is, earth is home to more insects than any other kind of animal. Insets are very unique, among all living creatures on the Earth.

Different Types of Invertebrates  

The body of an insect is divided into three parts head, thorax and the abdomen. The head contains the mouth, the eyes and the antennas. Some insects use their antennas for smelling. The thorax of an insect is similar to our chest. If an insect has wings, they are attached to this portion of the body i.e. thorax. The abdomen contains the large part of the digestive system. As the invertebrates lack bones, they have hard outer covering to support the body called chitin. This outer layer is waxy and waterproof. All insects have six legs. Invertebrates are found everywhere on the earth, land, water, air etc.


*         Vertebrates

The animals which have a back bone or a vertebral column are called vertebrates. These animals are highly evolved and have well developed organ system. Vertebrate is a large group. To study and understand the animals in this group, vertebrates are further divided into five major groups.



*           Fish

As the name suggest, these animals live in water. Both marine and fresh water fishes come under this group. The body of a fish is partly or wholly bony endoskeleton (internal skeleton) and is generally spindle shaped. The size of the body varies from 10 mm to 4 meters.

             Rohu Fish

The body of the fishes is either naked or covered with scales. These animals breathe through gills. They swim in water with the help of their fins. Some common example are labeo (rohu), mackerel, shark etc.


*       Amphibian

Amphibian, as clearly indicated by the word amphi means double and bios means life. Amphibian are animals that live both on land and in water. The body of these animals is divided into head, trunk and their heart is of three chamber. Respiration in amphibians takes place through gills, lungs, moist skin or the mouth lining. These animals do not maintain their body temperature (cold blooded). Their body temperature change with the environment.



 Some common examples of this group are frog, toad, newt and salamanders.


*         Reptiles

Reptiles are the group of animals living mainly on land. 'Reaper' is a Latin word meaning 'crawl'. Reptiles are known as creeping vertebrates. They are cold blooded, mainly terrestrial, but some may be aquatic. The body of the reptiles is covered with dry, water proof skin having horny scales.

       King Cobra

Body of the reptiles is usually divided into head, neck, trunk and tail, though the structure of the body may vary. Teeth are present in almost all reptiles except a few. Heart of these animals is three chambered. Most reptiles lay eggs on land. Examples are snake, lizards' tortoise, crocodile etc.


*       Birds

Birds are the most magnificent and easily differentiated group. This group is scientifically called AVES, a Latin word meaning bird. Animal of this group is highly evolved with well-developed organ and complex organ system. Bird are warm blooded (maintain their body temperature) vertebrates with several flight adaptations.




The size of this group of animals varies from the smallest humming bird to largest ostrich. Feathers cover most of the body. They have two legs and a pair of wings that help them to fly. Some birds such as kiwi, ostrich and penguin cannot fly. These birds are called flightless birds. The heart of the birds is fully formed with four chambers. Birds lays eggs. They are very good in taking care of their young one. Example, Sparrow, Crow, Eagle, Peacock etc.


*         Mammals

Mammals are the most evolved species of the animal's kingdom. They are the group of animals that give birth to their babies and mother suckle their young ones. The body of a mammal can be divided into four parts, head, neck, trunk and the tail.



 Mammals breathe through their lungs. Heart is completely formed with four chambers. They are warm blooded animals. Hair is present on body of the mammals. They show the highest degree of parental care i.e. parents taking care of their young one. Mammals are mostly terrestrial but they are also found in water, on the trees etc.

Primary example of mammals are human beings. Other example of this group are kangaroo, rat, monkey, tiger, elephant, whale etc.





       Which one of the following animal belongs to the group of amphibians?

(a) Dog

(b) Frog

(c) Whale

(d) Cat

(e) None of these


Answer: (b)


Frog belongs to the group of amphibians.



    Animals which give birth to their young ones are ______

(a) Aves

(b) Amphibians

(c) Insects

(d) Mammals

(e) Reptiles


Answer: (d)


Aves, Amphibians, Insects and Reptiles lays eggs..

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