Behaviour
Juvenile Periphylla periphylla - the red-coloured stomach is visible beneath the transparent bell. © L Madin, WHOI.
This jellyfish is strikingly bioluminescent. It can emit light from its body - expressed as localised flashes and waves - thanks to a chemical reaction. This may be a warning to possible predators that the animal is unpalatable.
Like other members of the group Cnidaria - including corals and sea anemones - this jellyfish has stinging cells on its tentacles to attack prey. One stinging cell - the eurytele - is larger in Periphylla periphylla than in any other jellyfish.
This species is known as a vertical migrator. It rises and falls in the water on a daily basis. At night it rises to shallower depths. Exposure to light results in fast downward-swimming, as this has a phototoxic effect on its pigment porphyrin.
Nutrition
This jellyfish feeds on crustacea, small fish and other medusae.
There is evidence that it behaves as an active predator.
It replaces fish in the food chain of Lurefjorden, where light conditions do not favour visual predators.
