Galactosomum


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