Galactosomum is a genus of flukes in the family Heterophyidae. There are currently 28 recognised species within the genus. They mainly infect aquatic birds, but often infest fish as larvae. Three species are known to use marine mammals as hosts. Description The excised spherical metacercaria is 2.7–4.9 mm long. Generally, only one is found per fish. Life cycle Some species of Galactosomum cause infected fish to swim closer to the surface and colorfully flash their underbellies. In fish, symptoms can be similar to those of whirling disease caused by the unrelated parasite Myxobolus cerebralis. 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. Species Galactosomum baylisi (Gohar, 1930) Galactosomum bearupi Pearson, 1973 Galactosomum cochlear (Diesing, 1850) Travassos, 1929 Galactosomum cochleariforme (Rudolphi, 1819) Pratt, 1911 Galactosomum darbyi Price, 1934 Galactosomum dollfusi Pearson, 1973 Galactosomum echinatum (Timon-David, 1955) Galactosomum erinaceum (Poirier, 1886) Galactosomum fregatae (Prudhoe, 1949) Galactosomum humbargari Park, 1936 Galactosomum johnsoni (Price, 1934) Galactosomum lacteum (Jägerskiöld, 1896) Galactosomum linguiforme Anantaraman, 1974 Galactosomum nicolai (Isaichikov, 1927) Galactosomum palawanense Fischthal & Kuntz, 1972 Galactosomum phalacrocoracis Yamaguti, 1939 Galactosomum puffini Yamaguti, 1941 Galactosomum renincola Pearson, 1973 Galactosomum sanaense Kobayashi, 1942 Galactosomum semifuscum (Olsson, 1876) Galactosomum sinuilactis Pearson, 1973 Galactosomum spinetum (Braun, 1901) Galactosomum stelleri Dailey, Demaree & Critchfield, 2002 Galactosomum timondavidi Pearson & Prévot, 1971 Galactosomum ubelakeri (Dailey, 1969) Pearson, 1977 Galactosomum ussuriense Oshmarin, 1963 Galactosomum witenbergi Anantaraman, 1974 Galactosomum yehi (Dissanaike, 1961) Pearson, 1973 References External links Heterophyidae Suicide-inducing parasitism