Key Characteristics of Phylum
How Many Species in Phylum
20,000
Structure and Function
- Roundworms have a complete digestive tract where nutrients are transported through the body in the pseudocoelomic fluid
- The body plan is often called a tube-within-a-tube
- Roundworms have a tough, transparent cuticle, that covers the outer-body (The cuticle sheds as the worm grows)
- Roundworms have longitudinal muscles the produce a thrashing motion
- Roundworms reproduce sexually only, with internal fertilization
Habitat
Interesting Facts
- Roundworms are the most common species of intestinal parasites in the world
- Roundworms are the second leading cause of blindness
- 50% of roundworms can live in the ocean