Rhizostoma pulmo, Barrel Jellyfish is one of the most common jellyfish in the Mediterranean Sea. In the video we see it swimming under the surface of the water letting itself be carried away by the current and the waves, this jellyfish is completely harmless and we can easily touch it on the umbrella, the tentacles are however slightly stinging so it is advisable to stay away from it even if the irritations are resolve within a few minutes.
These jellyfish are instead an important bioindicator and above all a source of food for dolphins, cetaceans, whales, and many other fish, and as you can see in the video, as soon as we pushed it under water, numerous fish immediately approached, in this case Seabream (diplodus sargus).
Barrel jellyfish (Rhizostoma pulmo Macri, 1778) is a sciphomedusa of the Rhizostomatidae family.
Distribution and habitat
It is a pelagic species widespread in the eastern Atlantic Ocean, in the Mediterranean Sea (frequent along the entire Adriatic and Ionian coasts, particularly in the late summer and early autumn periods) and in the Black Sea.
This jellyfish has a hemispherical hat that is opalescent but tending towards transparency, with blue-purple fringed edges. Under the hat, the body is called handlebar and is made up of 8 extensions of curled and lumpy white-transparent fabric, from which 8 elongated, fringed and semi-transparent tentacles depart.
Juvenile specimens tend to have a more transparent colouration, adults much more opalescent. The common name of sea lung is due to the typical throbbing movement made by the jellyfish to move. The dimensions are noteworthy: being able to reach 50-60 cm in diameter and 10 kg in weight, it represents the largest jellyfish in the Mediterranean.
The species does not cause serious consequences, its tentacles are not normally stinging enough to create serious dangers for humans. Only on particularly sensitive subjects, contact can cause irritation which disappears spontaneously in a short time but leaving an annoying itch or pain.