Are jellyfish going to take over the oceans? | Karl Mathiesen

Like a karmic device come to punish our planetary transgressions, jellyfish thrive on the environmental chaos humans create. Is the age of the jellyfish upon us?

Another British summer, another set of fear-mongering headlines about swarms of "deadly" jellyfish set to ruin your holiday. But news that jellyfish numbers may be rising carries implications far beyond the interrupted pastimes of the sunburnt masses.

Like a karmic device come to punish our planetary transgressions, jellyfish thrive on the chaos humans create. Overfishing wipes out their competitors and predators; warmer water from climate change encourages the spread of some jellies; pollution from fertilisers causes the ocean to lose its oxygen, a deprivation to which jellyfish are uniquely tolerant; coastal developments provide convenient, safe habitat for their polyps to hide. In addition, the great mixing of species transported across the world in the ballasts of ships opens up new, vulnerable ecosystems to these super-adaptors.