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Levels of Organization in Animals

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  • Last Updated : 26 May, 2022

A gathering of animal categories are all in one spot, with various designs and structures brought to the kingdom. North of 1,000,000 types of creatures has been described till now. The need for arrangement turns into even more important. The grouping additionally helps in assigning a systematic position to recent species.

R.H. Whittaker has proposed the 5 Kingdom classification. The Five Kingdom arrangements are done on the basis of specific characteristics like- the structure of the cell, method of nutrition, source of nutrition, interrelationship, body association, and reproduction. 

According to this framework, they are divided into-Monera, Protista, Fungi, Plantae, and Animal (the living beings which are put under the Kingdom of Animalia are heterotrophic and depend upon different creatures for food these are eukaryotic life forms with well-developed organelles). 

The kingdoms are subdivided into subgroups at various levels. The following levels show the Hierarchy of the classification  

  • Domain 
  • Kingdom
  • Phylum
  • Class
  • Order 
  • Family 
  • Genus 
  • Species

Levels of Organization

All individuals from Animalia are multicellular, every one of them doesn’t be a similar example of the association of cells. For instance, it wipes the cells are organized as free cell totals, they show cell level of association. Some division of exercises happens among the cells. In coelenterates, the plan of cells is complex. The cells playing out something very similar work organized into tissues, hence is tissue level of association. A still more significant level at the association. That is, organ level is displayed by individuals from Platyhelmthes and other higher phyla where tissues are assembled to shape organs, each specific for a specific capacity. In creatures like Annelids, Arthropods, Molluscs, Echinoderms, and Chordates, organs are related to shape utilitarian frameworks, every framework worried about a particular physiological capacity. This example is called organ framework level of association Organ frameworks in the various gatherings of creatures show different patterns of complexities. 

Cellular level

The cellular level is the most important level. A cell is the crucial unit of life and the littlest unit equipped for increasing itself. While the design and capacity of cells shift significantly contingent upon the living being, all cells share a couple of cells. Cells are made out of natural atoms, contain nucleic acids (like DNA and RNA), are loaded up with cytoplasm, and have a lipid-based film. Cells additionally have many designs called organelles inside their cytoplasm that fill different cell roles.  

Tissue level 

Tissue is the most important layer that plays a major role in the protection of the organ, and tissues allow only the required one into the organ and keep the organ safe.

Tissues are groups of similar cells from the same origin that work together to perform a specific function. Basic tissues in humans are classified into  Connective tissues, which are made up of fibrous cells that give organs shape and structure. Muscle tissue is composed of cells that can contract and allow  moving 
The outer layers of organs, the skin, and the stomach are made up of epithelial tissues. Nervous tissue, the spinal cord, and the brain is made up of specialized cells that transform information through electrochemical signals.

Organ level

An organ is a structure composed of various tissues that carry out specific bodily functions. Most organs contain tissues. The organ level is composed of the level combination of tissues together in one to perform a specific function.  Organs can be solid or hollow, and their size and complexity vary greatly. Organs include the heart, lungs, and brain next to this level organism level and which is a very complex level is composed of different organs to perform a particular thing to maintain the body 

Another basis on which we can classify the organisms are-


Creatures on the order based on their symmetry. Sponges are mostly asymmetrical, any plane that goes through the middle doesn’t partition them into two halves. When any plane going through the focal hub through the body partitions the life form into indistinguishable halves, it is called radial symmetry. Coelenterates, ctenophores, and echinoderms have this sort of body plan. Creatures like annelids, and arthropods. Where the body can isolate indistinguishable left and right parts as if it were one plane, exhibiting bilateral symmetry.

Diploblastic and Triploblastic Organization

Animals in which the cells are arranged in two embryonic layers, external ectoderm, and internal endoderm, are called diploblastic animals e.g.coelenterates.
An undifferentiated layer, mesoglea, is present in between the ectoderm. Those animals in which the developing embryo has a third germinal layer, mesoderm in 
between the ectoderm and endoderm are called trophoblast animals.


The presence or absence of a hole between the body divider and the stomach divider is vital in classification. The body cavity is lined by a mesoderm called coelom. Animals possessing coelomates are called coelomates. Annelids, Mollusca, Arthropods, Echinoderms, hemichordates, and chordates. In a few creatures, the body hole isn’t lined by the mesoderm is available as dissipated pockets between the ectoderm and endoderm. Such a body depression is called pseudocoelom such body pit are called pseudocoelomates, e.g. aschehelmenthes. The creatures in which the body pit is missing are called acoelomates. e.g. Platyhelminthes.


In certain creatures, the body is remotely and inside separated into fragments, with a sequential redundancy of at any rate some organs. For examples night crawler, it has the metamerism  division 


The notochord is a mesodermally determined pole-like design framed on the dorsal side during early-stage development in some animals.  Animals with notochord are called chordates and that creature that doesn’t shape this design is called non-chordates, e.g. Porifera to Echinoderms.

Conceptual Questions

Question 1: In Whittaker’s five kingdom classification,  eukaryotes were assigned? 


Eukaryotes are at 4 number-Plantae

Question 2: Who proposed a five-kingdom classification? 


R.H.WHITTAKER in 1969 

Question 3:Name the five kingdoms classified by the Whittaker?


Monera, Protista, Fungi, Plantae,  Animalia 

Question 4: List the levels of the organization?


  1. Cellular level 
  2. Tissue level 
  3. Organ level 
  4. Organ-system level 

Question 5: What is a tissue? And explain the tissue level of organization?


Tissue is a group of cells together is called tissue. The tissue level of organization is the level in between the levels for the formation of an organism and in that level, the cellular level turns into the tissue level and all the cells together and forming the tissues is the tissue level of organization.

Question 6: What is the organ level of the organization?


The organ level of organization is the level at which all the tissues are completely formed together to form an organ and at this level, some organs do the same thing to maintain the balance in the body(eg. metabolism, excretion, elimination, etc.) is organ level of organization.

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