Metamerism

Definition

Metamerism is the segmentation of an organism’s body into repetitive segments called metameres or somites. This biological feature is prominently seen in annelids and some other animal groups.

5 Must Know Facts For Your Next Test

1. Metamerism allows for greater flexibility and mobility in segmented organisms.
2. Annelids, such as earthworms, exhibit clear metamerism with repeated segments along their bodies.
3. Each segment, or metamere, can contain repeated organs and structures like nerve cells and excretory units.
4. Metamerism can be internal (e.g., repeating skeletal elements) or external (e.g., visible body segments).
5. In mollusks, metamerism is less pronounced but can still occur in certain species such as chitons.

Review Questions

• What are the advantages of metamerism in annelids?
• Which animal groups prominently display metamerism?
• How does metamerism contribute to the functionality of an organism's body?

Related terms

Segmentation:

The division of an organism's body into multiple parts or sections.

Somite: A segmental block-like structure found in developing embryos that gives rise to muscles and vertebrae.

Annelid:

A phylum of animals known for their segmented bodies, including earthworms and leeches.