Blue Dragons Invade Spain, Close Down Beaches

A stretch of beaches in southeastern Spain  shut down recently after venomous sea creatures known as “blue dragons” made an appearance. The bizarre-looking sea slugs invaded the shore near Guardamar del Segura, prompting local police to temporarily ban swimming.

“Due to the massive appearance of the Blue Dragon (Glaucus atlanticus), and for citizen safety reasons, SWIMMING is PROHIBITED on all beaches of the municipality until further notice,” Policía Local Guardamar wrote on Facebook.

Photo credit: Policía Local Guardamar via Facebook

The slugs began appearing elsewhere and in force, as far away as the Canary Islands, 1000 miles from the southeastern coast. “They kept appearing, one after the other, after the other, and at times on a massive scale,” José Luis Sáez, the mayor of Guardamar del Segura, tells the New York Times.

Blue Dragons tend to live in the open ocean, where they float upside-down on or near the surface, buoyant with a gas bubble in their stomachs. They float with the blue side of their bodies facing up, to blend in with the aquamarine hues of the water. 

They feed on Portuguese man o' war and other venomous jellyfish, and then show off their real superpower: the slugs not only absorb the toxins from its prey, but amplify the potency and use them as weapons, for either defense or more predation. The sting won’t kill a human, but it hurts – a lot – and causes redness, swelling, and vomiting.

Blue Dragons are usually far from beaches, but have also shown up in recent years on Phuket, Thailand and along the Texas coast in the Gulf of America (nee Mexico). They prefer warm, tropical waters but their intrusion into the Mediterranean is probably due to climate change, so we can expect them to be regulars here for the foreseeable future.

Photo credit: Sylke Rohrlach / Creative Commons