• 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.
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