Phylum Nematoda

1. Phylum Nematoda Roundworms

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

3. 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. Exploration of a Roundworm

5. 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. 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. 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. 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. 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.