The beach in the town of Gardama del Segura in southeastern Spain was closed earlier this week after two toxic sea slugs were found in the water, local authorities said.
“Due to the arrival of the Blue Dragon (Glaucus atlanticus) and the motivation for citizen safety, we have banned all swimming on all municipal beaches until new orders,” Guardamar police said in a Facebook post Wednesday.
Colloquially named for resembling a mythical creature, the Blue Dragon is about 3 cm (1.2 inches) long, but before recycled its venom and concentrating it, it feeds on poisonous animals like the Portuguese, paralyzing its size 300 times its size.