Be careful: Compass jellyfish increasingly common in the Bay of Kotor

AUTHOR:M.J. GDNUS

In the Bay of Kotor, we have been increasingly noticing one of the most recognizable jellyfish in the Mediterranean, also known as the compass jellyfish.

Although it appears elegant in the sea, this species can cause unpleasant skin reactions due to the stinging cells on its long tentacles.

It has a bell-shaped head, usually 10–15 cm in diameter, but it can grow up to 30 cm! It is recognizable by its radial dark stripes, which gave it its name, the compass jellyfish. Its body is adorned with long tentacles that it uses to capture food, while on the edge of the bell, on the long whitish tentacles, there are stinging cells that can cause redness, pain and irritation when in contact with the skin.

The compass jellyfish was first registered in our country in 2006, and since 2013 we have recorded it every year, usually from April to early June. This year it appeared a little later, probably due to the warm autumn, mild winter and increased rainfall, which affected its life cycle.

Two phases of the life cycle:

Chrysaora hysoscella goes through a polyp phase (attached to the substrate) and a medusa phase (free-swimming). The appearance of the jellyfish depends precisely on the development and "budding" of the polyp - a process called strobilation.

The compass jellyfish is very tolerant of temperature, but salinity plays a key role in its reproduction. Therefore, weather conditions, rainfall, as well as changes in sea currents and temperature, affect when and how many there will be. It is usually more often observed in bays as a result of waves and sea currents.

WHAT TO DO IN CONTACT WITH A JELLYFISH?

Rinse with seawater, carefully remove the remains of the tentacles with a card or other object.

If available, rinse with a solution of vinegar (4–6%) or baking soda in seawater.

Apply a cold compress (ice in the fabric, no direct contact with fresh water).

If necessary, apply antihistamine creams.

In case of a stronger reaction - contact a healthcare facility or pharmacy.

Report any encounter with this or similar jellyfish to the Institute of Marine Biology - your contribution is important for monitoring marine ecosystems.

Photo: Vesna Mačić