If their proliferation is not exceptional, the phenomenon would be earlier than in previous years. The water temperature rose faster, which promoted the development of plankton that jellyfish feed on, stimulating their growth and reproduction.
The most widespread species currently on the Atlantic coast is the "compass jellyfish" - whose stinging power is very strong. It is up to you to be careful not to be in their way, says an aquariology specialist who advises avoiding them in water and on the sand.