The primary difference between a coelom and a pseudocoelom is ________.

For one thing, the fluid inside cushions the organs suspended within it, helping to prevent internal injuries. The cavity allows internal organs to grow and move independently of the outer body wall. For example, were it not for your coelom, your body surface would warp noticeably every time your heart beat or your intestines contracted.  Coeloms also allowed animals to get bigger or at least thicker.

Fluids that move within the body cavity can serve the function of a circulatory system.

The body cavity can be used to store eggs.  Open a female frog during breeding season and the eggs stored in the body cavity obscure the organs.

A fluid-filled cavity acts as a hydrostatic skeleton for soft-bodied animals. An animal’s body is made mostly of water, and water is incompressible. This means that animals with internal, water-filled cavities have the capacity to resist outside pressure and the pull of gravity, and so can maintain a constant body shape. Because a coelom or pseudocoelom acts as a hydrostatic skeleton and allows its possessor to resist external pressure, coelomates and pseudocoelomates can burrow and locomote very effectively, at least in environments that offers resistance to the hydrostatic skeleton.

Distinctions were made among animals based on the type of body cavity possessed.

There are a few triploblastic animals that completely lack any sort of body cavity. These animals are known as acoelomates.

Some animals possess a “false” coelom called a pseudocoelom. These animals are known as pseudocoelomates. A pseudocoelom is a body cavity that lies between mesodermal and endodermal tissue and is, therefore, not completely surrounded by mesodermal tissue.

A “true” coelom is completely surrounded by mesodermal tissue, and can thus be subdivided into compartments. Animals with a true coelom are known as eucoelomates or simply coelomates.  Since mesoderm gives rise to muscle this means that in eucoelomates the muscles surrounding the gut are separate form the muscles near the outside or periphery of the body (the muscles controlling the appendages).

That digestion is no longer a function of the movement of the animal is the postulated advantage of a true coelom.  Digestion could proceed at a constant or faster rate, supplying more energy to the animal, enabling it to go faster, or become larger. This is somewhat a biased vertebrate viewpoint.   Other authors again looking at this type of coelom from a vertebrate viewpoint, feel a eucoelom can be divided more easily into sub compartments, allowing some isolation and better support between important organs or systems.

The coelom is a cavity present between the gut and the outer body wall. It is found in animals and serves as a basis of classification for the animal kingdom.

The presence of a body cavity that is lined by mesoderm is referred to as coelom, the presence of patches of mesoderm in the body cavity is termed pseudocoelom, and the total absence of body cavity is referred to as acoelom. The animals possessing the cavity are known as coelomates or eucoelomates, and those that do not have a cavity are known as acoelomates.

The coelomic activity is usually filled with a fluid called the coelomic fluid. In the fluid, many organs such as the kidney, heart and reproductive organs are suspended.

Let us now discuss the differences between a coelomate and an acoelomate animal in the table below.

Coelomate

Acoelomate

Description

Coelomates are organisms with a fluid-filled cavity between the gut wall and the outer body wall.

An acoelomate is an organism that does not contain a fluid-filled cavity in their bodies.

Type of animal

Both vertebrates and invertebrates.

Only invertebrates.

Organs

The organs, such as the kidney and heart, are suspended in the coelomic fluid. The coelom compartmentalises the animal’s body for the free movement and growth of the organs.

The organs are not suspended and cannot move freely for growth.

Protection

The coelomic fluid acts as a shock absorber and protects the internal organs from crushing.

There is no protection of internal organs from crushing.

Classification

The coelomates are divided into Protostomes and Deuterostomes on the basis of their embryological development.

No such classification.

Nutrients

The coelom provides a space for the diffusion of gases and nutrients.

Nutrient transport occurs through passive diffusion.

Organ System

The presence of coelom promotes complex organ systems in animals.

It does not promote complex organ systems.

Examples

Annelids, molluscs, arthropods, echinoderms, hemichordates and chordates.

Platyhelminthes

Explore BYJU’S Biology for more interesting topics.

Also Read:

• Differences Between Invertebrates And Vertebrates
• MCQs on Invertebrates for NEET 2022
• Types, Process of Nutrition in Animals
• MCQs on Coelom for NEET 2022

Frequently Asked Questions

What is the difference between an acoelomate, pseudocoelomate and coelomate?

Coelomates are organisms with a mesodermally lined body cavity, pseudocoelomates are organisms with patches of mesoderm on their body cavity, and acoelomates are organisms with no body cavity at all.

Does acoelomate have mesoderm?

Yes, the acoelomates do have a mesoderm, but instead of being filled with fluid, it is fully lined with tissues.

What are pseudocoelomates, and give three examples of the animals?

Pseudocoelomates are organisms that have patches of mesoderm on their body cavity. Examples: Roundworm, hookworm and pinworm.

What is the main difference between a coelom and pseudocoelom?

A pseudocoelom is a body cavity that lies between mesodermal and endodermal tissue and is, therefore, not completely surrounded by mesodermal tissue. A “true” coelom is completely surrounded by mesodermal tissue, and can thus be subdivided into compartments.

What is the difference between coelom and coelom?

The presence of a body cavity that is lined by mesoderm is referred to as coelom, the presence of patches of mesoderm in the body cavity is termed pseudocoelom, and the total absence of body cavity is referred to as acoelom.

What distinguishes a Coelomate animal from a pseudocoelomate animal is that coelomates?

have a body cavity, whereas pseudocoelomates have a solid body.

How would you best describe a pseudocoelom?

Pseudocoelom is the false body cavity that lies between the body wall and the gut. Nematodes have pseudocoelom. Was this answer helpful?