Main Difference – Coelomate vs Pseudocoelomate

Animals classified as coelomate or pseudocoelomate are identified by their body cavities.An animal's coelom is its body cavity.Coeloms develop from mesoderm during embryonic stages.This surrounds the digestive tract and other body organs.There is a fluid surrounding the coelom that serves as a hydroskeleton.In the body, the coelomic fluid enables fluid flow between internal organs.As well as transporting nutrients, gases, and waste materials, it also transports waste products.

Key Areas Covered

1. What is a Coelomate – Definition, Characteristics, Examples 2. What is a Pseudocoelomate – Definition, Characteristics, Examples 3. What are the Similarities Between Coelomate and Pseudocoelomate – Outline of Common Features 4. What is the Difference Between Coelomate and Pseudocoelomate – Comparison of Key Differences

Key Terms: Coelomate, Enterocoelomates, Hydroskeleton, Peritoneum, Pseudocoelomate, Schizocoelom, Triploblastic Animals


What is a Coelomate

The term coelomate refers to animals that have fluid-filled body cavities called coeloms located within the mesoderm. Mesoderm is the middle germ layer of triploblastic animals. Therefore, coelom separates the gut from the body wall. All the internal organs are suspended in the fluid called the coelomic fluid. This allows the free internal movement of the organs of the body independently from the body wall. Due to the free internal movements of the organs, the body of coelomates possesses more physiological flexibility compared to animals without a coelom. The coelom also protects the organs from compression and damage. Moreover, coelom also functions as a hydroskeleton and as a circulatory system. The hydroskeleton provides more rigidity to the body. Nutrients, gases, and metabolic wastes are transported through the blood stream in coelomates. The two types of coeloms are schizocoelom and enterocoelom.


Figure 1: Coelomate Structure

The schizocoelom is found in protostomes, whose blastopore develops into the mouth. In schizocoelomates, the body cavity is formed by the splitting of the mesoderm in a process called schizocoely. Their cleavage is spiral, and the fate of each body cell is already determined at its formation. The enterocoelom is found in deuterostomes whose blastopore develops into the anus. In enterocoelomates, the body cavity is formed by outpocketing the primitive gut, which breaks off to form the coelom in a process called enterocoely. The cleavage of the neterocoelomates is radial, and the fate of the cells are not determined at their formation. Therefore, these cells can differentiate into many cell types. The basic structure of a coelomate animal is shown in figure 1. 

What is a Pseudocoelomate

.Among triploblastic mammals, the endoderm is the innermost germ layer.Pseudocoeloms are space in the blastula, also called blastocoels.Because pseudocoelomates only have an open circulatory system, pseudocoeloms act as a medium for nutrient, gas, and waste transfers.In addition, the pseudocoelom serves as a structure that provides structural support.


Figure 2: Pseudocoelomate Structure

A few examples of pseudodelenchians include Nematoda, Entoprocta, Rotifera, Acenthocephala, and Gastrotrica.A pseudocoelomate has the following basic structure, as shown in figure 2.

Similarities Between Coelomate and Pseudocoelomate

Difference Between Coelomate and Pseudocoelomate


Coelomate: A coelomate is an organism with a body cavity between the body wall and the digestive tract.

Pseudocoelomate: A pseudocoelomate is an invertebrate with a fluid-filled body cavity between the endoderm and the mesoderm.

Alternative Names

Coelomate: Coelomates are called eucoelomates.

Pseudocoelomate: Pseudocoelomates are called blastocoelomates and hemocoelomates.

Body Cavity

Coelomate: Coelomates possess a body cavity called coelom.

Pseudocoelomate: Pseudocoelomates possess a body cavity called pseudocoelom.

Location of the Body Cavity

Coelomate: The body cavity of coelomates is inside the mesoderm.

Pseudocoelomate: The body cavity of pseudocoelomates is between endoderm and mesoderm.


Coelomate: The body cavity of coelomates is lined with peritoneum.

Pseudocoelomate: The body cavity of pseudocoelomates is partially lined with peritoneum.

Origin of the Body Cavity 

Coelomate: The coelom is derived by splitting of the mesoderm.

Pseudocoelomate: The pseudocoelom is derived from the blastocoel of the embryo.


Coelomate: In the coelom, the nutrients circulate through the blood stream.

Pseudocoelomate: In the pseudocoelom, the nutrients diffuse through diffusion and osmosis.

Organization of the Organs

Coelomate: The organs of the coelomates are well-organized inside the coelom.

Pseudocoelomate: The organs of the pseudocoelomates are less-organized inside the pseudocoelom.


Coelomate: Coelomates can be either vertebrates or invertebrates.

Pseudocoelomate: Pseudocoelomates are invertebrtaes.


Coelomate: Annelida, Arthropoda, Mollusca, Echinordermata, Hemichordata, and Chordate are coelomates.

Pseudocoelomate: Nematoda, Entoprocta, Rotifera, Acenthocephala, and Gastrotrica are examples of pseoducoelomates.


Coelomate and pseudocoelomate are two types of animals classified based on the type of body cavity present in each animal. Both coelomates and pseudocoelomates are triploblastic animals with complete digestive systems. Coelomates possess a body cavity called coelom inside the mesoderm. Pseudocoelomates possess a body cavity called pseudocoelom between the endoderm and the mesoderm. Both coelom and pseudocoelom are fluid-filled cavities, which serve as hydroskeletons. The main difference between coelomate and pseudocoelomate is the type of body cavity in each class of animals. 

This is why:.ANISSIMOV, MARKEL, and BROHNWELL HARRIS.Coeloms: What are they?””. .Id.Infoplease, "Pseudocoelomate." Available here.Last accessed 6 Sept. 2017.

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