1. Simple InvertebratesSection 4 Phylum Nematoda Roundworms

2. Simple InvertebratesSection 4 Characteristics of Roundworms Bilaterally symmetrical body with a pseudocoelom 3 embryonic tissue layers Digestive system with separate openings for feeding and waste elimination

3. Simple InvertebratesSection 4 Free-living roundworms are active hunters that feed on bacteria, fungi, protists, or small invertebrates. Some species are parasitic that feed on plants or animals. Roundworms usually produce sexually. Nutrients absorb through the fluid in the pseudocoelom.

4. Simple InvertebratesSection 4 Exploration of a Roundworm

5. Simple InvertebratesSection 4 Groups of Roundworms Common parasitic roundworms include; pinworms, hookworms, filarial worms, and ascarids/ Ascaris. As many as 50% of preschool and school-age children are infected with pinworms. Filarial worms are a group of long, thin roundworms that live as adults in the blood or other tissues of vertebrates, including humans.

6. Simple InvertebratesSection 4 Groups of Roundworms, continued Filarial worms are a group of long, thin roundworms that live as adults in the blood or other tissues of vertebrates, including humans.

7. Simple InvertebratesSection 4 Groups of Roundworms, continued Ascarids are roundworms that live in the intestines of pigs, horses, and humans. Ascarids feed on food that passes through the intestines of their host. They can block the host’s intestines if left untreated.

8. Simple InvertebratesSection 4 Fighting Parasites Human are hosts to a number of flatworm and roundworm parasites. A large part of the problem is that almost half of the world’s population lives in areas with inadequate sewage systems. In addition, about 1 billion people do not have access to clean water.

9. Simple InvertebratesSection 4 Fighting Parasites, continued To prevent parasitic infections, people who live in or travel to places where parasites are common should; –wash hands frequently, –drink bottled or boiled water –eat only fully cooked meat –use insect repellent, wear protective clothing, and sleep under netting.