Sylt beaches see first swarm of subtropical jellyfish

A swarm of subtropical by-the-wind sailors (Velella velella) has been washed up on the beaches of the German island of Sylt, marking a first for the North Sea. These jellyfish, which are harmless to humans, are characterized by a dark blue disc and a transparent sail.

Experts, including Rainer Borcherding from the Schutzstation Wattenmeer, describe the event as a sign of climate change. The presence of these creatures suggests that parts of the Atlantic Ocean have become significantly warmer, as the species typically requires winter water temperatures of at least 14 degrees Celsius to thrive. While the jellyfish are expected to visit the region again in the future, the North Sea is currently too shallow for them to complete their reproductive cycle, which requires descending to depths of over 1,000 meters.