Phylum Nematoda (Round Worms)

Wikipedia Entry

Approximate Number of Species: 22,00

Largest: Placentonema gigantissima, a parasite on the reproductive tracts of female right whales, can reach lengths of approximately 27.6 feet (8.4 meters)

Smallest: Species Micronema, living between individual grains of sediment, only reach lengths of 0.012 inches (0.3 mm)

References:

Brusca RC & Brusca GJ (2003) Invertebrates (Sinauer Associates, Inc., Publishers, Sunderland, MA) 2nd Ed.

Gubanov NM (1951) Giant nematoda from the placenta of Cetacea; Placentonmea gigantissima nov. gen., nov. sp. Doklady Akademii Nauk SSSR 77(6):1123-1125.

Johnson JS, Hibler CP, Tillotson KM, & Mason GL (2001) Radiculomeningomyelitis dute to Halicephalobus gingivalis in a horse. Veterinary Pathology 38:559-561.