Pelagia

While ascending from a night dive, in the first few meters, the beam suddenly catches a small mauve umbrella suspended in the darkness. Eight fine tentacles gently follow the movement of the water: a Pelagia.

What the lamp reveals, however, is only part of the story, for Pelagia noctiluca can itself produce light. Its bioluminescence is quite real: when stimulated, it is capable of emitting a glow, a property to which its name noctiluca, "light of night," directly refers.

Even more remarkable, this jellyfish needs no fixed refuge on the bottom to complete its cycle. In many scyphozoans, a larva attaches and becomes a polyp before producing young jellyfish; in Pelagia, this phase disappears.

The larva evolves directly into a young jellyfish: its entire existence unfolds in open water. The coasts are not even its only domain.

It lives widely offshore, and work conducted in the Ligurian Sea shows that certain massive arrivals toward the coast can be caused by currents and wind episodes. Before the diver, the umbrella simply continues its drift, then glides out of the beam, carrying with it this strange life entirely suspended in water.