The species was first sighted in Montana in a pond adjacent to the Missouri River near Great Falls in 2009. Since then, no other major sightings have been reported in the state until this summer. The species is native to eastern Asia and is now found on almost every continent, as well as most states in the U.S.
The familiar free-floating “medusa” phase of this jellyfish’s life cycle only appears sporadically during warm summer months, while most of their life is spent attached to underwater surfaces as microscopic polyps that go dormant in winter. Like some fish in Montana such as paddlefish and cisco, the freshwater jellyfish feeds on zooplankton, an important foundational component of aquatic food webs.
Unlike some of its well-known marine counterparts, the freshwater jellyfish is harmless to humans.
It’s unknown how the species made its way to Montana or whether the discovery near Canyon Ferry is related to the state’s initial sighting 17 years earlier. Also unclear are the possible ecological impacts of the jellyfish’s presence in Montana waters as a non-native species, though it does not appear to have had significant impacts in other states.
