Atolla Jelly
Atolla jellies like this one live in the ocean’s twilight zone, where red light doesn’t penetrate. So, without the bright ROV around, this jelly would be nearly invisible. However, Atollas are also bioluminescent, able to make their own light when they need to stand out. They can produce flashes of bright blue, useful for startling predators or luring in prey, according to the Woods Hole Oceanographic Institution. This ability means they’re sometimes called alarm jellies.
Note: that’s not a piece of fishing line or dental floss. Atolla jellyfish have one extra-long and thin tentacle that’s used to help capture prey and possibly for reproduction.
