Nature Notebook – Freshwater Jellyfish

The girls chattered about the jellyfish that they saw while canoeing. Instead of dismissing this as childish whimsy, our naturalist, Mindy, had them direct her to their observation area. Now all of the students were treated to the sight of a freshwater jellyfish bloom.

The tiny jellies (size of a quarter) in the hydromedusa stage of their life cycle were a bit easier to spot. The much smaller larva and polyp stages are miniscule. Just like “regular” jellyfish, these jellies have a number of tentacles. They are used for swimming and catching tinier invertebrates. Although the nematocysts (stingers) are effective on small invertebrates, they cannot harm humans.

Their impact upon their non-native home (they originated in China) has yet to be determined. They have been in Michigan since 1930 and are established in most of the United States.