Overview

• Guardamar del Segura in Alicante shifted from a red flag to a yellow flag on Thursday after closing 11 kilometers of coastline when two Glaucus atlanticus were found at Playa Vivers.
• Mayor José Luis Sáez said bathing was initially prohibited for 12–24 hours under a protocol that increased lifeguard surveillance and issued loudspeaker alerts.
• Local guidance warns not to touch the animals, not even with gloves, to rinse any contact area with seawater, and to seek medical attention if symptoms occur.
• The 3–4 cm pelagic nudibranch stores stinging cells from prey such as the Portuguese man o’ war, causing intense pain, nausea and vomiting, yet it is not considered lethal and no severe or fatal cases have been reported in the recent sightings.
• Sightings and short‑term closures have also been reported this summer in Mallorca, Cádiz, Lanzarote, Gran Canaria and Valencia, with experts linking the increase to anomalously warm sea temperatures.