Annelida
Definition
Annelida is a phylum of segmented worms characterized by their ring-like body segments called annuli. They include earthworms, leeches, and marine polychaetes.
5 Must Know Facts For Your Next Test
- Annelids have a true coelom that functions as a hydrostatic skeleton.
- They possess both longitudinal and circular muscles for movement.
- Annelids exhibit metamerism, meaning their bodies are divided into repeating segments.
- They have a closed circulatory system with blood vessels.
- Most annelids have specialized structures called setae or chaetae for locomotion.
Review Questions
- What type of body cavity do annelids possess?
- How do annelids achieve movement?
- What is the significance of metamerism in annelids?
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Related terms
Mollusca: A diverse phylum of soft-bodied animals often protected by a hard shell, including snails, clams, and octopuses.
Setae: Bristle-like structures found on annelids that aid in locomotion.
Polychaetes: A class of marine annelid worms known for their parapodia and numerous bristles.
