Eucoelomates

Definition

Eucoelomates are animals with a true coelom, a fluid-filled body cavity completely lined by mesodermal tissue. This anatomical feature allows for more complex organ development and greater body flexibility.

5 Must Know Facts For Your Next Test

1. Eucoelomates possess a coelom that is entirely lined with mesoderm, distinguishing them from pseudocoelomates and acoelomates.
2. The presence of a true coelom allows for the development of more advanced organ systems.
3. Examples of eucoelomates include annelids, mollusks, arthropods, echinoderms, and chordates.
4. The coelomic cavity can serve various functions such as acting as a hydrostatic skeleton or providing space for organ growth and movement.
5. Eucoelomates exhibit greater complexity in both their structure and function compared to animals without a true coelom.

Review Questions

• What distinguishes eucoelomates from pseudocoelomates and acoelomates?
• Name three phyla that include eucoelomate animals.
• How does having a true coelom benefit eucoelomate animals?

Related terms

Pseudocoelomate: Animals with a body cavity not fully lined by mesodermal tissue.

Acoelomate: Animals lacking any body cavity between the digestive tract and outer body wall.

Mesoderm: The middle layer of an embryo in early development which gives rise to muscles, bones, and other organs in most animals.