Coeloms are an integral part of multicellular organisms. It is essentially a body cavity that has been present over the years as a result of continuous evolution. This coelomic cavity has further aided in performing multiple functions of the body. The living body, in its current evolutionary form, now has three layers of skin over the skeleton. Notably, the presence of coelom has helped the body in fighting against various odds like those of impact and similar injuries.

To know more about what is coelom and its features and functions, you need to read further. 

Structure and Formation of Coelom

As already mentioned, the coelom is a fluid cavity in a living body. It is present right under the external layer of skin. More specifically, it is present in between the wall of a body and alimentary canal.

Look at the picture below. It shows the three types of animals that possess coeloms.

In simple words, this fluidic cavity is like a cushion that protects internal organs from external jerks and jolts. Now, go through the following structural details for a clear understanding.

  • Coelomates

An organism having a true coelom is called coelomate. They have the fluidic acuity located in between the outer body wall and gut. There is a mesodermal lining on both sides too. The gastrula has the blastocoel which is entirely omitted, and a coelom is located there in its stead. 

Example - coelom in Annelida to the phylum Chordata.

  • Acoelomates

As the name implies, the coelom is absent in this category of animals. Herein, the blastocoel is the main part that functions and replaces the coelom entirely. They lack the fluid cavity and instead grow from a triploblastic structure which are endoderm, ectoderm and mesoderm.

Example - phylum Porifera, Coelenterata. 

  • Pseudocoelomates 

This type of coelom indicates a false coelomic structure. Simply put, the true coelom is not found in such cases. Instead, the mesodermal cells fill the blastocoel, and the lining is present only on the side of the body wall. However, there is no mesodermal on the gut side.

Example - roundworms, horsehair worms, human pinworm.

So, as you can see, the coelomic cavity has variations, based on which animals are classified. Revise them thoroughly for a deeper understanding to write in your NEET exam.

Importance of Coelom

Coeloms are fluid like cavities that protect the inner organs of a living body. Besides, they also provide several other benefits, which are discussed below -

  • It acts as a shock absorber from the external environment. It provides a necessary cushion for the internal organs to be flexible.

  • For soft-bodied animals, the fluid provides a way for locomotion. Also, it gives them a definite shape.

  • It provides extra space for the digestive organs to grow. For instance, the gastrointestinal tract. It requires a considerable amount of space inside the body to grow and perform its functions.

  • Other organs like gonads require a wider space during the breeding season in certain animals.

  • In some animals, this coelom is most active in the formation of the blood circulatory system as well. It aids in the formation of a heart and other blood vessels for carrying blood to and from the heart.

  • In some instances, animals fill in their coelom with food, which diffuses into their blood. The required nutrients from those food molecules are distributed to specific organs, as required.

Now, with all these functionalities and significances listed above, it is evident that coelom plays a vital role in animals. While in the vertebrates, it protects the internal organs, for invertebrates, it acts as a skeleton helping them in locomotion while also providing them with a shape.

Types of Coelom

Based on the nature of the formation, true coeloms are divided into two main categories - Schizocoelom and enterocoelom. 

  • In the former coelom type, the mesoderm splits to form this fluid cavity. It is present between the endoderm and ectoderm, which develops into a coelom.

Example - Annelida, Mollusca, etc.

  • In the case of the latter, the internal outgrowth of archenteron fuses to form their coelom. The mesoderm lines it on all sides. 

Example - Chordata, Echinodermata, etc.

Thus, we have seen two kinds of classification of coeloms in animals. You have to be cautious while studying the classification and keeping a distinction between both. Take help of examples to remember them.

Additionally, being able to classify them appropriately is an added benefit. Therefore, make sure to revise them regularly and keep a note of each type. Mixing them up will only add to mistakes in your exams. 

To help you further with your preparation, some other tips are discussed hereunder.

Last-Minute Tips for Acing the NEET Exam

NEET is not a child’s play, and therefore, it requires you to be prepared at all levels. When studying the coelomic cavity, try to make the most of your time effectively. Follow a routine during the exam preparation and identify your weaker areas of your syllabus while also revising your stronger areas every day. Opting for regular tests is another must to prepare adequately for your NEET.

Along with understanding what is coelom and other similar topics, you should also focus on keeping yourself fit. In this regard, the daily routine should also be of help.

So, gear up and prepare well for your exam.

FAQ (Frequently Asked Questions)

1. What is coelom?

Ans. Coelom is a fluidic cavity that is present right under the outer wall of a living body. It acts as a soft cushion cover and protects the internal organs, especially the digestive system, from external disturbances.

2. What are the organism distinctions based on coelom?

Ans. There are three types of animals based on the presence or absence of a coelom. They are coelomates, acoelomates and pseudocoelomates. Notably, molluscs, annelids, etc. are coelomates as they have the coelom layer between the digestive and their body.

3. When does the coelom evolve?

Ans. The evolution of coelom occurs during embryogenesis for living beings. This cavity contains the stomach, gallbladder, pancreas, liver, and organs responsible for digestion.