Summary:
- Roundworms make up the phylum Nematoda.
- This is a very diverse animal phyla.
- It has more than 80,000 known species.
- They range in length from less than 1 millimeter to over 7 meters (23 feet) in length.
- Free-living roundworms are found mainly in freshwater habitats.
- Parasitic roundworms have a variety of hosts, including humans.
- Pinworms are the most common roundworm parasites of people in the U.S.
- In some areas, as many as one out of three children are infected.