Enterocoely

Diagram illustrating the process of enterocoely.

Enterocoely is a developmental process observed in certain animals, particularly in the phylum Echinodermata. It involves the formation of the coelom, a fluid-filled body cavity, through a specific mechanism known as enterocoelic pouching. This process is distinct from other modes of coelom formation, such as schizocoely.

Mechanism

During enterocoely, the coelom is formed from the endoderm, the innermost germ layer of the developing embryo. The process begins with the invagination of the endodermal cells, forming pouches or evaginations. These pouches then pinch off from the endoderm, creating small cavities within the mesoderm. These cavities eventually fuse together to form the coelom.

Significance

Enterocoely is an important developmental process as it plays a crucial role in the formation of various organ systems in animals. The coelom serves as a protective and supportive structure for internal organs, allowing them to move and function independently. It also provides a space for the circulation of fluids, facilitating nutrient transport and waste removal.

Examples

Enterocoely is most commonly observed in echinoderms, a diverse group of marine animals that includes starfish, sea urchins, and sea cucumbers. In these organisms, the coelom develops through enterocoelic pouching during embryonic development.

Evolutionary Significance

The evolutionary origin of enterocoely is still a subject of debate among scientists. Some propose that it represents an ancestral condition, as it is observed in various animal phyla, including chordates and hemichordates. Others argue that enterocoely has evolved independently multiple times in different lineages.

See Also

• Coelom
• Schizocoely
• Echinodermata