Moon Jellyfish on the Moors

Moon jellyfish are among the most graceful and recognisable jellyfish found around the coasts of Devon and Cornwall. Their pale, almost transparent bodies pulse gently through the water, often revealing the distinctive four horseshoe-shaped rings inside the bell. In bright sunlight they can appear ghostly white or faintly blue, drifting just beneath the surface in harbours, estuaries, and sheltered coves.

Despite their delicate appearance, moon jellyfish are efficient predators, feeding on plankton, tiny fish larvae, and microscopic sea life. They do not actively hunt in the way fish do; instead, they drift with tides and currents, using their trailing tentacles to catch food as it passes. Their movement is slow and hypnotic, making them fascinating to watch from harbour walls, beaches, or boats in calm weather.

For visitors exploring the South West, sightings are most likely in warmer months when seas are calmer and plankton levels rise. Places such as Teignmouth, Plymouth Sound, and sheltered Cornish estuaries can sometimes host large blooms of moon jellyfish, turning clear water into a drifting constellation of translucent bells. While generally harmless to humans, it’s best to admire them without touching, especially if they have washed ashore.