Freshwater Jellyfish
Turns out jellyfish aren’t just found in oceans; they can also be spotted in lakes and rivers – even in Canada. They’re known as Peach Blossom Jellyfish and while they’ve been in some areas for a while, they’re expanding their range.
What Do They Look Like?
Peach Blossom Jellyfish have two forms – the polyp stage and the medusa stage.
Most of their lives are spent as a polyp, easily going unnoticed. Polyps are small, around one to two millimetres in size. They are found near the bottom of lakes and attach themselves to hard surfaces and vegetation. In this stage they reproduce by budding (asexually) and feed on zooplankton. They can survive Canada’s cold winters by becoming dormant.
When water temperatures heat up above 21°C they transform from the polyp stage to the medusa stage. This is when they look like jellyfish and become noticeable. They are bell-shaped and translucent. They are about five to 25 millimetres in diameter and have a whitish or greenish colour. They are found in the water column, and they also feed on zooplankton. They have tentacles, but unlike their saltwater relatives, they do not sting people. In this phase they reproduce sexually and can appear in large numbers that are referred to as a bloom.
Where Are They Found?
They are not native to Canada and are invasive. They are thought to originate from Asia. They are now found on every continent except Antarctica. In Canada, they have been reported in several provinces, including Ontario.
The Future
It is expected that as temperatures warm, Peach Blossom Jellyfish will continue to expand their range.
What Can We Do?
Be sure to clean, drain and dry all equipment before moving to another water body. And if you do see jellyfish floating in your lake, report it to the Ontario Invasive Species Hotline at 1-800-563-7711.
For more information on how you can show your lake some love, visit LoveYourLake.ca.
Love Your Lake is a shoreline assessment program developed by the Canadian Wildlife Federation and Watersheds Canada.
Written by Terri-Lee Reid, Freshwater Researcher with the Canadian Wildlife Federation
