Galactosomum

Taxobox | name = "Galactosomum"
regnum = Animalia
phylum = Platyhelminthes
classis = Trematoda
ordo = Opisthorchiida
familia = Heteryophyidae
genus = "Galactosomum"
genus_authority = Looss, 1899

"Galactosomum" is a genus of flukes within the family Heterophyidae, which is part of the order Opisthorchiida. There are currently twenty-one recognised species within the genus. They mainly infect aquatic birds, but often infest fish as larvae [cite book|last=Hoffman|first=Glenn L.|title=Parasites of North American Freshwater Fishes|publisher=Cornell University Press|location=512 East State St., Ithaca, NY 14850|date=1999|pages=11|chapter=Some North American Fish Parasites Listed by Location in the Fish|isbn=0-8014-3409-2|url=http://books.google.com/books?id=ZU5iqP3NJpMC&pg=PA11&vq=Galactosomum&dq=Galactosomum+fish+parasite&lr=&source=gbs_search_s&cad=5&sig=ACfU3U0rTQ78-kZ_h0j3Efhjh-5-UU08cA|language=English] . Three species are known to use marine mammals as hosts.

Physical Description

The excised spherical metacercaria is 2.7-4.9 mm long. [cite journal|last=Kamegai|first=S.|coauthors=N. Yasunaga, S. Ogawa and S. Yasumoto|date=1982|title="Galactosomum sp". from intestine of "Larus carassirostris" from Nagasaki, Japan|journal=Jpn. J. Parasit.|pages=31|language=Japanese] Generally, only one is found per fish. [cite journal|last=Kimura|first=M.|coauthors=Endo, M.|date=1979|title=Whirling disease caused by metacercaria of a fluke|journal=Fish Pathol.|volume=13|pages=211–213|language=Japanese]

Life Cycle

The genus is inaccurately known as a species in popular culture, due to its mention in "Resident Evil 4" as an example of a parasite which controls, or alters, the behavior of the host. This is based on some species of Galactosomum that cause infected fish to swim closer to the surface and colorfully flash their underbellies [cite web|url=http://fishparasite.fs.a.u-tokyo.ac.jp/Galactosomum%20sp/Galactosomum-eng.html|title=Database of Parasites in Fish and Shellfish|accessdate=2008-07-03] . Gastropods hosting select species suffer from sensory impairment due to infestation. This makes these prey animals more likely to be consumed by aquatic birds, providing a host for the parasite to reach the mature stage of its life cycle. "Galactosomum" cannot survive in human hosts. [cite web|url=http://fishparasite.fs.a.u-tokyo.ac.jp/Galactosomum%20sp/Galactosomum-eng.html|title=Database of Parasites in Fish and Shellfish|accessdate=2008-07-03]

References