Cotylorhiza tuberculata is a species of jellyfish of the phylum Cnidaria, also known as the Mediterranean jellyfish, Mediterranean jelly, or fried egg jellyfish. It is commonly found in the Mediterranean Sea. Beautiful and elegant, it lends itself well to underwater photography and video shooting, making itself admired by all those who love the sea.

Pennaria disticha, also known as the Christmas tree hydroid, is a species of athecate hydroid in the family Pennariidae. Colonies are common in the Mediterranean Sea growing on rocks close to the surface. This species has been used in research into prey capture. Colonies of Pennaria disticha consist of numerous much-branched stems up to 30 cm high. The branching system is alternate.

Pelagia noctiluca is ajellyfish in the family Pelagiidae. It is typically known in English as the mauve stinger, but other common names are purple-striped jelly (causing potential confusion with chrysaora colorata), purple stinger, purple jellyfish, luminous jellyfish and night-light jellyfish. Pelagia noctiluca can be described as a marine organism with the ability to glow in the dark (bioluminescence). It is found worldwide in tropical and warm temperate seas.