Cassiopea andromeda

Cassiopea andromeda
Upside-down jellyfish

Mild stinging


It is a mild-stinging species and therefore with little or no effect on humans. Even so, it is recommended not to touch it since it may produce some type of dermal reaction after the contact in very sensitive persons.


Flatenned umbrela yellowish brown with streaks and pale white spots. It can reach a maximum size of 30 cm in diameter. It has 8 branched oral arms with presence of unicellular symbiotic algae (zooxanthellae) that give the jellyfish a greenish or brownish color. It lacks marginal tentacles.

As its common name indicates, this jellyfish is generally inverted, with its oral arms facing up, which allows unicellular algae to photosynthesize and the pulsation of the umbrela causes water to flow through its arms for respiration and feeding.


There are no records of its presence along the Catalan coast.

Distribution and Habitat

It is native to the Indo-Pacific, and it is typically found in shallow lagoons, in sands of the intertidal zone or mud areas, or around mangroves.

The entrance to the Mediterranean was through the Suez Canal where it was first sighted in Cyprus in 1903. It currently inhabits some areas of the eastern Mediterranean coast, such as some Greek islands, Israel and the coast of Turkey. There are no records of its presence on the Catalan coast.