Striking yellow-brown jellyfish have been spotted off Pula and near Brijuni. They are neither an introduced plague nor considered dangerous—but they still do not belong in children's hands or on the beach.
What was actually observed off Pula
Numerous adult specimens of the Mediterranean jellyfish Cotylorhiza tuberculata were observed in mid-August at the Mornar bathing area at the end of Pula's Lungomare. According to the Faculty of Natural Sciences in Pula, local density was roughly two animals per square metre. Larger groups had already been noticed at Havajska Beach on Verudela in late July; in early August, Brijuni National Park also reported this distinctive species in its waters.
These observations document a conspicuous local concentration at several points along southern Istria's coast. They do not show that every beach in Istria is affected or that the animals are evenly spread throughout the northern Adriatic. Wind, currents and moving water masses can gather jellyfish in one bay while leaving them barely visible just a few kilometres away. For today's swim, the beach in front of you matters—not the most dramatic headline from another bay.
Why it looks like a fried egg
The common name describes the view from above remarkably well. The bell is flat, yellowish to greenish brown, with a rounded, darker dome in the centre. Beneath it are highly branched oral arms bearing many white and violet terminal knobs. Adult animals often reach a bell diameter of around thirty centimetres; Aquarium Pula says mature specimens can measure up to about forty centimetres toward the end of August.
The colour does not come from the animal alone. Symbiotic microalgae known as zooxanthellae live in its tissue. Through photosynthesis, they produce nutrients and supply part of the jellyfish's energy. This explains why the animals often drift through well-lit upper layers of the water—and why the yellow-brown bell is more than a pretty camouflage colour.
A native jellyfish, not an invasion
Features of the fried egg jellyfish and four rules for respectful observation
Not dangerous does not mean made for touching
Brijuni National Park, Aquarium Pula and specialists in Pula consistently describe Cotylorhiza tuberculata as harmless to people. Its stinging apparatus is much weaker than that of more troublesome Adriatic species. Contact does not normally cause a serious injury. That is the reassuring news for swimmers.
Precision still matters: particularly sensitive people may feel slight stinging or mild skin irritation. Mucus and detached tissue should not enter the eyes or mouth either. Anyone noticing a reaction should leave the water calmly, avoid rubbing and seek medical assessment for stronger, widespread or general symptoms. Golden Beach therefore does not endorse a test of courage: watching and taking photographs makes more sense than touching.
While swimming: give it space and stay calm
One fried egg jellyfish is no reason to flee the beach. If you see one while swimming, leave it several metres of room and calmly change direction. Do not use fins, paddles or hands to push it away. If there is a dense group, another entry point or a short break is more pleasant than weaving through the animals.
Parents should explain to small children that even an apparently soft, slow animal is not something to pick up. Do not touch remains washed ashore either: stinging capsules can still react in tissue, and the species is harder to identify reliably from a disintegrating bell. If in doubt, ask a lifeguard, dive centre or local aquarium—not the loudest person on the beach.
Why the jellyfish belongs in the sea
The University of Pula expressly asked people not to take the animals out of the water. Young fish seek shelter from predators beneath their bells. Aquarium Pula mentions juvenile horse mackerel, Mediterranean horse mackerel and saddled seabream among them. At first glance, a jellyfish is simply passing by; ecologically, it can also be a small moving refuge.
Even a dead bell remains part of the food web and is used by other marine organisms. Throwing a jellyfish onto the beach does not merely remove a supposed nuisance; it interferes with an existing relationship. Lifting it out also creates unnecessary direct skin contact. The most practical conservation message in this article is therefore the simplest: leave it in the water.
Young fish travel beneath the bell
Underwater images show small fish close above or below the bell. They remain near the oral arms because the slowly pulsating animal provides cover. For swimmers, this detail is a good reason to look more closely: a fried egg jellyfish is not just a single animal, but at times the centre of a tiny mobile community.
This does not mean every jellyfish is visibly accompanied by fish, or that you should follow one for a photograph. It does explain why specialists particularly object to taking them out. Anyone using a mask or underwater camera should keep their distance, avoid blocking its path and refrain from turning or positioning the animal. Real behaviour is more interesting than a staged image.
A concentration is not yet an invasion
Cotylorhiza tuberculata belongs to the Mediterranean and is native to the Adriatic. Adult animals are regularly visible in summer and early autumn. Appearing in especially large numbers in one year or at one beach does not make the species invasive. The word invasion suggests a foreign intruder and a widespread threat—neither is supported by the current observations.
The figure of about two animals per square metre must not be extrapolated to all of Pula or Istria either. It describes an observed local density at Mornar bathing area. Longer-term conclusions would require systematic time series, current data and comparable surveys. The responsible interim assessment is this: conspicuous seasonal gatherings of a native species, not a blanket jellyfish plague.
How a photograph can help research
Sightings are useful when they contain more than a blurry picture. A photograph from above and—if possible without approaching—from the side, along with the date, a precise location and an approximate number of animals, helps specialists assess the report. The Crafting the Sea platform collects observations from the Adriatic and links citizen sightings with marine research.
A report does not replace an official warning service and should never be forced from inside a dense group. Safety and undisturbed observation come first. Anyone who suspects a different, more strongly stinging species or develops pronounced symptoms after contact should not treat the situation like an innocuous fried egg jellyfish. Identification in a social-media comment is not a medical diagnosis.
What remains uncertain for the next beach day
The current reports do not predict which beach the animals will drift past tomorrow. A bay can change overnight. A calm morning does not rule out a later concentration either. On site, the condition of the water, the wind, notices from beach staff and your own observations matter. The presence of this species does not justify a general swimming ban.
The lasting rule is simple: recognise it, keep your distance and do not lift it out. Look closely and you are not encountering a yellow nuisance, but a native Mediterranean species with symbiotic algae and small fellow travellers. The sea has not become more dangerous that day—only more visible.
Evidence
Sources & date
Sources support the facts. Planning notes and recommendations are Golden Beach editorial assessments.
- Beauty of the Adriatic in the waters of Brijuni National ParkBrijuni National Park · 7 August 2026; checked 22 August 2026current sighting, risk assessment, possible mild skin irritation and no-touch guidance
- Jellyfish at Aquarium PulaAquarium Pula · ongoing species information; checked 22 August 2026identifying features, maturity, size, symbiotic algae, weak stinging apparatus and young fish
- Jellyfish fill a Pula bathing area: experts say they are not dangeroustportal citing the Faculty of Natural Sciences in Pula · 18 August 2026; checked 22 August 2026local concentration at Mornar, roughly two animals per square metre and appeal to leave them in the sea
- Crafting the Seacitizen-science platform for the Adriatic · ongoing service; checked 22 August 2026voluntary route for submitting sightings with a photograph and location
- Fried Egg Jellyfish Izola 2019-08-29Alisa Parashchenko / Wikimedia Commons · photographed 29 August 2019; licence checked 22 August 2026lead and social image, CC BY-SA 4.0; species portrait, not a current Pula photograph
- Cotylorhiza tuberculata with little fish on topCisamarc / Wikimedia Commons · photographed 4 January 2009; licence checked 22 August 2026inline image with young fish, CC BY-SA 3.0; species and behaviour portrait
