A peculiar marine discovery has surprised scientists in Mallorca. Last Friday, biologist Gádor Muntaner and paramotor pilot César Canudas discovered a specimen of “blue dragon” while sailing off the north-west coast of the island. This rare mollusc, known scientifically as glaucus atlanticus, represents an extraordinary sighting in the Mediterranean, where there have been hardly any documented records since the early 18th century. “Glaucus atlanticus is a mollusc, a nudibranch gastropod. It is quite common in the Atlantic and the Canary Islands, but there are very few records in the Mediterranean Sea. It is a very, very rare organism,” explained the expert after the discovery.
The specimen found, which was almost the maximum size for the species (between 3 and 4 centimetres), was returned to the sea after being observed. This sighting represents a significant milestone for the Balearics, where the presence of this species had not been documented since 1705, while the last record on the mainland was in Alicante in April 2023. The biologist also highlighted the specific characteristics of this organism’s habitat: “It is a species of pelagic areas, it is neither on the coast nor on the seabed, but in the blue, in the open sea. Its maximum size is about 3 or 4 centimetres, so this one is one of the largest”.
The “blue dragon” is a small mollusc which, despite its small size, hides a fascinating and potentially dangerous nature. This pelagic nudibranch belongs to the Glaucidae family and is characterised by its striking silvery blue colour, which serves as perfect camouflage on the ocean surface, where its ventral (darker) side blends in with the blue of the sea when viewed from above, while its lighter dorsal side mimics the sunlight when viewed from below.
Dangers and effects of its sting
What makes this species truly unique is its diet and defence mechanism. The “blue dragon” feeds mainly on other stinging organisms such as the Portuguese man-of-war, jellyfish and other cnidarians. During feeding, this ingenious mollusc not only consumes the tissue of its prey, but is also able to extract and store intact the stinging cells (nematocysts) of these organisms for later use in its own defence, a phenomenon known as kleptocnidia.
This defensive system makes the seemingly harmless blue dragon a potentially dangerous animal for humans, as it can concentrate toxins that are more powerful than those of the organisms it feeds on, thus increasing its toxicity. Although encounters with blue dragons in Mediterranean waters are extremely rare, it is important to be aware of the effects of contact, as it can be very painful and, in some cases, dangerous. When touched, there is a risk that this mollusc will release the toxins accumulated from its prey, causing various symptoms that vary in intensity depending on the sensitivity of each person and the amount of toxin injected.
The main effects of a blue dragon sting include: intense pain and a burning sensation in the area of contact; visible redness and swelling of the affected area; possible nausea or vomiting in more severe cases; difficulty breathing in extreme situations; and allergic reactions which, although rare, can lead to anaphylaxis.
What to do if you get stung
In case of contact with a blue dragon, it is essential to follow an appropriate protocol to minimise the effects of the toxin and avoid complications. Experts recommend these specific guidelines:
1. Do not use vinegar or fresh water to clean the affected area, as these liquids can trigger a greater release of toxins, worsening the situation.
2. Rinse thoroughly with salt water to remove any stinging cells that may remain on the skin.
3. Carefully remove any visible fragments of tentacles using tweezers or protective gloves, never with bare hands.
4. Apply cold compresses to the affected area to relieve pain and reduce inflammation.
5. Seek medical attention as soon as possible, especially if severe symptoms such as difficulty breathing, severe dizziness or signs of an allergic reaction occur.
Why is it so rare to find it in the Mediterranean?
The exceptional sighting of the blue dragon in Mediterranean waters is due to several biogeographical and ecological factors. This nudibranch is native to temperate and tropical oceans, mainly the Atlantic, Pacific and Indian, where surface currents facilitate its dispersal. Its presence in the Mediterranean, a semi-enclosed sea with different characteristics, is unusual and could be related to phenomena such as climate change or alterations in sea currents.
In addition, its dependence on other pelagic species such as the Portuguese man-of-war, which are also uncommon in the Mediterranean, partly explains its rarity in these waters. Several scientific studies suggest that changes in water temperature and marine current patterns resulting from climate change could be altering the distribution of species such as the blue dragon. The progressive warming of the Mediterranean could be creating more favourable conditions for organisms traditionally associated with warmer or more open waters.
This phenomenon is part of what biologists call the “tropicalisation” of the Mediterranean, a process whereby species typical of tropical and subtropical seas begin to establish themselves in these waters, altering local ecosystems and generating new ecological interactions. The recent discovery in Mallorca may not be an isolated incident, but part of a broader pattern of changes in Mediterranean marine biodiversity that scientists are continuing to monitor closely to better understand its long-term ecological implications.