Coelom

Definition

A coelom is a fluid-filled body cavity completely lined by mesoderm tissue. It provides space for the development and suspension of internal organs.

5 Must Know Facts For Your Next Test

1. The coelom allows for the separation and independent movement of internal organs.
2. Coelomates are animals that possess a true coelom, whereas acoelomates lack this cavity.
3. It plays a crucial role in the classification of animals within the Bilateria group.
4. The presence of a coelom enables more complex organ systems to develop, such as circulatory and digestive systems.
5. Examples of coelomate animals include annelids, mollusks, and vertebrates.

Review Questions

• What is the primary function of a coelom in animal anatomy?
• How does having a coelom benefit an organism compared to being an acoelomate?
• Name two groups of animals that are considered coelomates.

Related terms

Mesoderm: The middle layer of embryonic tissue from which the coelom forms.

Acoelomate: An animal lacking a coelomic cavity, with tissues packed between gut and body wall.

Pseudocoelom: A body cavity partially lined with mesodermal tissue, found in pseudocoelomates like nematodes.