Jellyfish of the Cassiopea genus are the only ones that rest with their umbrellas on the ocean floor and their tentacles pointing upward.
This unique quality has earned them the nickname of ‘upside-down jellyfish’. This curious position allows them to receive enough light for the symbiotic algae that they host in their tissues.
Thanks to photosynthesis, those algae produce carbohydrates that the jellyfish use as the basis of their diet.
They supplement this by catching floating animals with their stinging tentacles. Their sting can have different effects on humans, depending on sensitivity to the toxin: rash, vomiting, and so on.
Cassiopea jellyfish are often accompanied by shrimp – sometimes many of them – that take shelter between the branches of their oral arms and inside their umbrellas.
«The names of cnidarian species are often taken from Greek mythology. For example, Cassiopeia, Andromeda's mother, was punished by Poseidon for having failed to keep a promise. He sent her up into the heavens in a basket that was forever turning over and over.»
