Lorraine Williamson
A rare and strikingly beautiful but venomous sea creature, known as the blue dragon (Glaucus atlanticus), has been sighted off the shores of Mallorca. This has ignited both fascination and caution among marine experts and beachgoers alike.
This marks the first documented appearance of the species in the Balearic Islands for over three centuries.
While the blue dragon is usually associated with warmer Atlantic waters, particularly off the coasts of Australia, South Africa, and parts of the Gulf of Mexico, recent years have seen an uptick in sightings across Spain. In 2023, the nudibranch was recorded along the Costa Blanca, near Alicante and Torrevieja, and prior to that off the Canary Islands. Its latest reappearance in the Mediterranean suggests a possible shift or expansion in its habitat range, likely influenced by warming sea temperatures and shifting ocean currents — both potential indicators of broader environmental changes.
Striking appearance masks lethal defence
Despite its delicate size — rarely exceeding 3 to 4 centimetres — the blue dragon is far from harmless. Its electric blue and silver hues serve both as a warning and as camouflage against the shimmering ocean surface. Unlike many molluscs, this species lacks a shell, relying instead on a sophisticated chemical defence.
Feeding primarily on venomous prey such as the Portuguese man-of-war (Physalia physalis) and Velella velella (commonly known as “by-the-wind sailors”), the blue dragon stores the potent venom from its victims within finger-like appendages called cerata. Remarkably, it not only neutralises the toxins for its own protection but concentrates them, making its own sting potentially even more painful than that of its prey.
Encounters with the creature can result in intense localised pain, skin irritation, swelling, nausea, and in some cases, severe allergic reactions. Although rarely life-threatening, the effects closely mimic those experienced from contact with the Portuguese man-of-war.
Growing risk for summer swimmers
As summer currents push these creatures closer to shore, Spanish marine authorities are warning the public to remain vigilant. The vibrant colours can tempt the curious — especially children — to pick them up, unaware of the danger.
Experts advise that in case of accidental contact, affected skin should be rinsed gently with seawater, avoiding fresh water and rubbing, which can worsen symptoms. Medical attention should be sought if any severe reactions occur.
Possible impact of climate change
Marine biologists are increasingly monitoring such sightings as potential indicators of climate change’s impact on marine biodiversity. Warmer sea temperatures, altered current patterns, and shifts in prey availability may all be contributing to the blue dragon’s rare visits to Mediterranean shores.
In the past, sightings of Glaucus atlanticus in European waters were so exceptional that many considered them a once-in-a-lifetime occurrence. Now, their more frequent presence may signal a changing balance in the ecosystem, raising both scientific interest and public safety concerns.
Public awareness
With the Mediterranean experiencing unprecedented environmental pressures, from overfishing to rising sea temperatures, experts expect to see more unusual species appearing in the coming years. Spanish authorities continue to monitor these developments closely, balancing public awareness with marine conservation efforts.
For now, holidaymakers are urged to admire the blue dragon from a distance — its beauty is best appreciated through photographs rather than firsthand contact.
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