1. Phylum Nematoda
The Roundworms

2. Characteristics 12,000 species named Live everywhere Often parasites
Pseudocoelomates
Cylindrical shape
Most less than 5 cm
Can be microscopic to 1 meter in length

3. More Characteristics Nonliving (noncellular) cuticle
Longitudinal muscles only
No circular muscles
Alimentary canal: mouth to anus
Important in decomposition and soil nutrients

4. Classification

5. Major Parasites Ascaris Hookworm Pinworm Trichina Whipworm
Filarial worms

6. Ascaris An intestinal roundworm
Common infection in horses, humans, and pigs.
May lay 200,000 eggs per day
Abdominal symptoms

7. Hookworm Curved anterior resembles a hook Hook to intestines
Causes anemia in patient
Found in soil, burrow through skin, most commonly foot

8. Hookworm
Hookworm larvae
Hookworm eggs

9. Pinworm Most common parasite in the United States
Lives in large intestine and cecum.
Females lay eggs in anal area at night
Eggs develop within 6 hours, resulting in itching. If swallowed, mature in large intestine
Pinworm egg

10. Trichina Produces trichinosis
Adult worms burrow in small intestine and produce live young
Juveniles enter blood vessels and are carried to muscles

11. Whipworm Common in North America in humans Intestinal infection
Occurs through contaminated food or unhygienic habits

12. Filarial Worms At least 8 species that infect humans
Includes Elephantiasis, river blindness, dog heartworm
Worms live in the lymphatic system
Carried by mosquitoes

13. Dog Heartworm