Jellyfish in Sardinia, Arpas monitoring: only one “dangerous” species spotted

In all 361 sightings, for a total of 10 species. Summer is approaching and, for obvious reasons, the opportunities for unpleasant close encounters with jellyfish are increasing. But how many are there in the sea of Sardinia? And how dangerous are they? The answers to these questions are given in the recent report drawn up by Arpas, which conducted a monitoring in the sea of the Island.

First of all, there is the definition of “jellyfish”: «The term refers to a specific stage in the biological cycle of a complex group of animals belonging to the cnidaria phylum, a taxonomic category characterized by the presence of stinging cells (cnidocytes) distributed on the tentacles». And it is here, in the tentacles, that the “danger” lurks. Among the species spotted, only one is a red dot, in the sense that it is defined as “very stinging”. Most are harmless, or almost, to humans.

The area characterized by a higher number of sightings was that of northern Sardinia, "with maximum values recorded in the area of Porto Torres (101 observations). The marine sector of Villasimius instead represents the one with the greatest biodiversity, with the discovery of six different species".

The most widespread is the Velella velella with 114 sightings, often in very large colonies: encountered very often in the north, less so in the Cagliari area, the Barchetta di San Pietro (that's what it's called) has toxins that are harmless to humans, "producing a slight tingling sensation on the skin in case of contact".

The species Cotylorhiza tuberculata was also very abundant, well represented in all areas of Sardinia and harmless, as was the Pelagia noctiluca, a scyphomedusa that represents the most stinging among those observed: also known as the "luminous jellyfish", it is the one with the red mark, among the most stinging in the Mediterranean. Although it does not cause serious burns, it causes very painful reactions.

Of great importance is the presence of the distant species of Phyllorhiza punctata, of Pacific origin, «introduced by human activities and reported in the Mediterranean Sea since 1965. This currently represents the only non-native species found during the monitoring activities of the Marine Strategy in Sardinia»: it is the polka-dotted one, which does not create problems in case of contact.

Then there is the sea lung, which is a harmless species for humans, "even if contact can cause itching, dermatitis and redness in particularly sensitive subjects".

The Compass jellyfish, on the other hand, is a stinging species, whose effects (dermatitis, itching and burning) appear within 20 minutes of contact and disappear within a few hours: it has been sighted exclusively in the marine areas of central and southern Sardinia. A total of 4 individuals have been sighted, mainly in 2019 (75%). The Oristano area recorded 50% of the sightings. The Red-spotted Sinophore, on the other hand, has been sighted only in the Olbia area. It is stinging like the Olindia jellyfish, intercepted exclusively in the areas of Villasimius (in 2021) and Cagliari (in 2022), for a total of four individuals».