Difference Between Coelom and Pseudocoelom

Coelom vs Pseudocoelom

Coeloms and pseudocoeloms are words to explain the nature of the body cavity in animals. These body cavities are called coeloms. This cavity has surrounded by three cell layers called Ectoderm (outer layer), Endoderm (inner layer) and Mesoderm (middle layer) .

These cell layers are formed in embryo through the process called gastrulation, and eventually these cell layers become different parts of the body. This coelom and pseudocoelom act as hydrostatic skeleton, and disseminate the pressure through the body to minimize the damages of the internal organs.

Coelom acts as a shock absorber and hydrostatic skeleton. Longitudinal and circular waves can be transmitted efficiently through the hydrostatic skeleton.

There are two types of animals, diploblastic animals and triptoblastic animals, which have been categorized according to the development of the embryo. Diploblastic animals, as the name implies, have two cell layers i.e. the outer layer, which is called ectoderm, and the inner layer called endoderm.

Triptoblastic animals have an extra cell layer between Ectoderm and Endoderm which is called Mesoderm. Only triptoblastic animals have the body cavities.

What is Pseudocoelom?

Animals that have pseudocoelom or false coelom are called pseudocoelomate such as phylum Nematoda, Acanthocephala, Entoprocta, Rotifera, Gastrotricha1. Although they have a body cavity, it is not lined with peritoneum or partially lined with peritoneum , which is derived by embryonic mesoderm.

This body cavity is filled with fluid, which suspends the internal organs and separates the digestive tract and outer body cell wall. As embryology implies, the pseudocoelom is derived from the blastocoel of the embryo.

What is Coelom?

Animals that have true coelom are called Eucoelomates such as phylum Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata and Chordata. The fluid filled body cavity is lined with peritoneum, which is derived by embryonic mesoderm, and separates the digestive tract and outer body cell wall.

Internal organs are suspended in the body cavity and help to develop those. According to the embryology, Coelom is derived from two different ways. One way is through the splitting of the mesoderm, and the other way is out pocketing of archenteron fusing together to form the coelom.

What is the difference between Pseudocoelom and Coelom?

  • The main difference between Pseudocoelom and coelom is, pseudocoelom is not lined with the peritoneum, which is derived by embryonic mesoderm, whereas coelom is lined with the peritoneum.
  • Pseudocoelom is derived from the blastocoel of the embryo whereas coelom is derived in two different ways such as the splitting of the mesoderm and out pocketing of archenteron fusing together to form the coelom.
  • In coelomates, organs are suspended in a well-organized manner, in the body cavity, by attaching organs to each other whereas, in pseudocoelomates, organs are held loosely and are not well organized as in coelomates.
  • Coelom allows the formation of an efficient circulatory system whereas pseudocoelom does not aid in the formation of a circulatory system.
  • In Psudocoelom, nutrients circulate through diffusion and osmosis whereas, in coelom, nutrients circulate through the blood system.
  • The coelom is segmented whereas pseudocoelom is not segmented.
  • Pseudocoelom lacks muscles or supporting mesenteries, which coelom has.

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