Blue Jelly

Cyanea lamarckii

The Blue Jelly exhibits a bell that can vary in color from pale when young to a purple-blue or yellow as it matures. It typically reaches sizes between 10 to 20 cm across, with some specimens growing up to 30 cm. Unlike the larger lion's mane jellyfish, the Blue Jelly has a more translucent bell and is identifiable by its numerous stinging tentacles and large mouth arms that feature many wrinkles and ripples. This jellyfish can be found in the pelagic zone off the west coast of Scotland, throughout the North Sea, the English Channel, and the Irish Sea, often inhabiting depths ranging from 22 to 150 meters. It tends to drift closer to shore to feed on abundant plankton, including phytoplankton and zooplankton, as well as the eggs and larvae of various aquatic animals. Breeding occurs between January and March, when medusae bud and detach from mature polyps, similar to the life cycle of the moon jellyfish. These jellyfish have a relatively short lifespan, living for less than a year. Encountering a Blue Jelly while diving can be intriguing, as they drift gracefully through the water, their tentacles trailing behind them. Divers should take care to avoid contact with their stinging tentacles, which are used both for capturing prey and for defense against predators. The conservation status of the Blue Jelly is not evaluated.