Nematoda

Definition

Nematoda, also known as roundworms, are a phylum of parasitic and free-living worms with a complete digestive system. They have a cylindrical body shape and can infect various plants and animals, including humans.

5 Must Know Facts For Your Next Test

1. Nematodes have a complete digestive system with a mouth, intestine, and anus.
2. They exhibit sexual dimorphism, meaning males and females differ in appearance.
3. The cuticle is a tough but flexible outer covering that protects nematodes from harsh environmental conditions.
4. Many nematodes are parasitic and can cause diseases like ascariasis and filariasis in humans.
5. Nematodes lack a circulatory and respiratory system; they rely on diffusion for gas exchange.

Review Questions

• What kind of digestive system do Nematoda possess?
• How does the cuticle benefit nematodes?
• Name two diseases caused by parasitic nematodes in humans.

Related terms

Platyhelminthes:

A phylum of flatworms that includes both free-living and parasitic species.

Ascariasis:

A disease caused by infection with the parasitic roundworm Ascaris lumbricoides.

Cuticle: A tough but flexible outer layer that covers nematodes and provides protection.