Cayak in Canada

Both groups are ancient animals, having roamed the seas for at least 500 million years. And, in the modern age, they are having similar effects on ecosystems. As seawater temperature rises, predators of jellies are removed by fishing, more structures are built in seawater, and more nutrients flow into the ocean, some types of jellyfish and comb jellies may be finding it easier to grow and survive. Whatever the reason, huge explosions in jelly numbers (a jelly bloom) can disrupt fisheries, make for unpleasant swimming, or foul up the works of power plants that use seawater for cooling. Invasive jellies have also wreaked havoc in some parts of the world.