MUSKOKA — An unexpected creature is lurking below the surface of Muskoka’s waterways.

“They likely entered Ontario on a contaminated boat, other contaminated recreational equipment, or possibly as a contaminant in a shipment of imported aquatic plants,” said Jeff Brinsmead, senior invasive species biologist with the Ministry of Natural Resources and Forestry (MNRF), of freshwater jellyfish, on which the province is collecting data.

According to the MNRF, freshwater jellyfish have been reported in Lake Muskoka and Kahshe Lake (Kilworthy), as well as confirmed sightings in Prospect Lake (Uffington/Vankoughnet), Bala Bay, Otter Lake (Dorset), Pickerel Lake (Burk’s Falls), Restoule Lake, and Doe Lake (Sprucedale).

Brinsmead explained freshwater jellyfish are native to the Yangtze River basin in China. He said they were discovered in Regents Park in London, England, in the late 1800s, “likely introduced as a hitchhiker with imported aquatic plants” and they were found about the same time in Philadelphia, Pa., “presumed to have been released from ballast water.”

According to Brinsmead, it’s not known yet what the impact of the invasive species will be.

“Impacts have not been documented,” he said. “The freshwater jellyfish feeds on microorganisms in the water column. So, they are competing with other organisms, which feed on the same sources. This may impact fish populations in a body of water, especially if there is a large, established population of jellies; however, freshwater jellyfish are also eaten by native species in Ontario, so it is unlikely that they will have a noticeable impact on ecosystems.”

Brinsmead said freshwater jellyfish survive on zooplankton, which are organisms that have animallike traits and float, drift or weakly swim in the water. The biggest forms of zooplankton are only five-millimetres long and the smallest are just one thousandth of this size.

Using a very fine-meshed net, a scoop through the water then dumped into a jar and held up to the light, could reveal some of the larger species of freshwater zooplankton.

On the opposite end, the jellyfish themselves make a welcome snack for area predators including crayfish, turtles, and possibly geese and larger fish, said Brinsmead.

Even though these jellyfish have stinging cells, called cnidocytes, which are used to paralyze their prey, Brinsmead said they aren’t likely to sting people.