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Classification Of Animals

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Organisms are classified into different categories based on their criteria. The animal kingdom is one of those classifications. The animal kingdom is also called “Animalia”. The animal kingdom or Animalia consists of billions of organisms and millions of species. Classification is very important to study the organisms, to give names, etc. It includes all extinct, endangered, and endemic animals. Classification gives a particular position to recently added or discovered organisms. Animals are multicellular, eukaryotic organisms. The members of the animal kingdom are classified into different categories as phyla and classes based on their features and characteristics. Hereunder is a detailed explanation of the classification of Animal Kingdom.

Classification of Animal Kingdom

Classification of Animals


Phylum – Porifera

The organisms belonging to this phyla are usually known as sponges. These sponges have the system of water transport system in their body. These are usually marine animals, which means most of them live in oceans and seas. These are multicellular organisms and have cellular levels. The skeleton of these organisms is made up of spicules. Reproduction in sponges is done asexually by the process of fragmentation and sexually by the process of Gametes formation. Fertilization in these organisms is internal.

Examples: Euspongia and Spongilla.

Phylum – Coelenterata (Cnidaria)

These organisms are more symmetrical when compared to other organisms. These are mostly aquatic and free-swim animals that live in marines, seas, and other aquatic places. These organisms have Cnidoblasts on their tentacles and body. These Cnidoblasts are used in their defense mechanism and to capture the food. Cnidarians have mainly two body forms known as polyp and medusa. Polyp produces medusae using asexual reproduction and medusae produce polyp using sexual reproduction.

Examples: Gorgonia, Meandrina, and Physalia.

Phylum – Ctenophora

Ctenophores are usually known by the names such as Sea walnuts. These are diploblastic organisms that live in marines and are radially symmetric. The organization in these organisms is of tissue-level organization. The process of digestion takes place both intracellularly and extracellularly. In Ctenophores reproduction takes place only by sexual reproduction. fertilisation take place 

Example: Pleurobrachia and Ctenoplana.

Phylum – Platyhelminthes

They have flattened body-like structures. So, they are called flatworms. These organisms are found in many organisms including human beings. parasitic worms have hooks and suckers on their body. Many of these flatworms absorb nutrients from their host’s body directly through their body to survive. These organisms have special cells named flame cells which help in the process of excretion. Sexes are not separate in these worms. The process of fertilization occurs internally and development happens through several larva stages.

Example: Taenia (commonly known as tapeworm) and Fasciola.

 Phylum – Aschelminthes

The shape of the body of Aschelminthes is circular. These organisms may be aquatic or terrestrial parasitic organisms that live in both plants and animals. These organisms choose either plants or other animals as their host and live. They have organs in their body. These organisms are bilaterally symmetric in nature. sexes are separate in these organisms as we can distinguish male and female in Aschelminthes. Usually, female organisms are longer than male organisms. The process of fertilization takes place internally and the development of the organism may be direct or indirect.

Example: Ascaris (commonly known as roundworm) and Ancylostoma(Hookworm).

Phylum – Annelida

These organisms can live in both water and on land. They can live in both salt and fresh water. The organization of the body is organ level system. Their circular muscles and longitudinal muscles help in their locomotion. Their body surfaces can become fragments. Nephridia help in excretion in these organisms. Reproduction in these organisms is sexual.

Example: Nereis and Pheretima (common name is Earthworm).

Phylum – Arthropoda

The largest phylum among Animalia is Arthropoda. This phylum includes insects. Almost 66 percent of species on earth belong to the phylum of Arthropoda. The organisms in this phylum have organs in their body. These organisms are bilaterally symmetrical. In these kinds of organisms, excretion takes place through Malpighian tubes. Their bodies consist of the head, eyes, thorax, abdomen, etc. Respiration in Arthropods takes place through the lungs and gills. Fertilization is mostly internal and development happens either directly or indirectly.

Examples: Apis(bee), Bombyx, Limulus, Locusta, and Anopheles.

Phylum – Mollusca

The second largest phylum after Arthropoda in the whole animal kingdom is the Mollusca phylum. The organisms that belong to this phylum are both aquatic and terrestrial animals. They can live in both fresh water and brine water. The body of these organisms is covered with a shell called a calcareous shell. With a muscular foot, visceral mass, and head, its body is unsegmented. The space between mantle and visceral mass is usually known as the mantle cavity. They have gills-like structures to breathe. These are mostly unisexual.

Example: Octopus, Loligo, and pila

Phylum – Echinodermata

Mostly, organisms belonging to the phylum of Echinodermata are marine animals. They live in salt water. Fully grown echinoderms are radially symmetrical. But, in the larva stage, they are bilaterally symmetrical. They possess a water vascular system for locomotion, the process of respiration, and capturing food. There are no specially defined excretory organs in these organisms. The nervous system and sense organs are poorly developed in echinoderms and the brain is absent. sexes are mostly separate and the fertilization process is external.

Example: Antedon, Cucumaria, and Ophiura

Phylum – Hemichordata

The phylum hemichordate was initially placed in the sub-phylum of Chordata. Now it is considered a separate phylum under non-chordates. These organisms are worm-like structures and mostly aquatic animals. They mostly live in marine water. Their body is in a cylindrical structure. Respiration in these creatures is done through gills that open into the pharynx. They have a dorsal heart.

Example: Saccoglossus and Balanoglossus


The animals which don’t have notochord in their body come under the category of non-chordates. The central nervous system present in non-chordates is non-ganglionated, dorsal, hollow, and single. Phylum like Porifera, Arthropoda, Annelida, Aschelminthes, Platyhelminthes, Ctenophora, and Coelenterata are the parts of non-chordates.

Phylum – Chordata

The animals which have notochord in their body come under the category of chordates.
Chordates are further classified into three subphyla:

  1. SubphylumUrochordata or Tunicata: The organisms in the subphylum Urochordata are marine organisms and we can find them from the surface to depths in the ocean. Their body is composed of a tunic which is formed by cellulose and their body is unsegmented. The circular system in their body is of circular type. Activities like free swimming develop in their tadpoles larvae with tails. They have a ventral heart which reverses the flow of blood. Example: Salpa, Pyrosoma, and Doliolum
  2. SubphylumCephalochordata: Cephalochordates are aquatic animals. We can find these animals mostly in marine water. They possess a notochord, pharyngeal slits, and tubular nerve chords. Respiration occurs through their body surface. The circulatory system in their body is closed type. Excretion in Cephalochordata is done through solenocytes. The process of fertilization is external. Example: Branchiostoma
  3. SubphylumVertebrata: The Subphylum Vertebrata is divided into many classes:
    • Amphibia
    • Reptilia
    • Aves
    • Mammalia
    • Pisces

Class – Amphibia

These organisms are usually cold-blooded animals and have organs in their bodies. Amphibians require aquatic habitats or places to lay their eggs. These organisms do respiration mainly through their skin. They have two limbs and moist skin which helps in respiration.

Example: Frog, Salamander, and toddler

Class – Reptilia

Organisms belonging to a class of Reptilia are most commonly cold-blooded animals and have scales-like structures on their bodies. Reptiles have skeletons and external ears. But, some reptiles like snakes don’t have any ears and are deaf. They know about animals by the vibrations through the ground.

Example: snakes, tortoises, and lizards

Class – Aves

Most of the Aves are birds. The bodies of Aves are designed to have low air resistance. Because to fly in the air. Aves have external limbs, legs, feathers, and wings. These are warm-blooded animals and have control over their body temperatures. Most of the Aves have beaks to get their food.

Example: pigeons and parrots (all birds)

Class- Mammalia

Mammals are warm-blooded animals and have organs in their bodies. Mammals have external ears, hair, and eyes, and have four limbs. Mammals give birth directly to their new generation. Humans belong to the class of mammals. Mammals have skin that covers all the internal organs. With the help of limbs, mammals can walk, swim and do many other things.

Example: Human beings, cows, buffalo, etc.

Class – Pisces

Pisces are aquatic animals and cold-blooded animals. They have small fins which help them to swim through the water. They have some special breathing organs known as gills, which help them in breathing. These organisms have a skeleton structure.

Example: all fishes come under this class.

FAQs on Classification of Animal Kingdom

Question 1: Name any five phyla of the animal kingdom.


  1. Coelenterata
  2. Porifera
  3. Annelida
  4. Arthropoda
  5. Aschelminthes

Question 2: What is the phylum Annelida? Explain with some examples.


These organisms can live in both water and on land. They can live in both marine and freshwater. The organization of the body is organ level system.

Examples: Nereis and Pheretima (common name is Earthworm)

Question 3: What are the types of chordates?


Chordates are classified into three subphyla. They are,

  1. Subphylum – Urochordata
  2. Subphylum – Cephalochordata
  3. Subphylum – Vertebrata

Question 4: How does a snake know about the movement of its surrounding animals?


Snake knows about its surrounding animals by the vibrations through the ground.

Question 5: Define the animal kingdom.


The animal kingdom is also called “Animalia”. It is a multicellular, eukaryotic organism.

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Last Updated : 05 Dec, 2022
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