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Monster Jellyfish With 40ft Tentacles Surfaces
17 Sep
Summary
- A massive 40-foot lion's mane jellyfish was filmed off the Welsh coast.
- Its tentacles, used for hunting, can extend up to 120 feet in length.
- While its sting is described as 'nasty,' it is not life-threatening.

A remarkable sighting of a massive 40-foot lion's mane jellyfish has been captured off the coast of Wales. A free diver encountered the extraordinary creature, describing its tentacles as extending beyond visibility and its overall length comparable to a bus. This encounter, near Trefin in West Wales, involved observing at least 20 of these jellyfish in a shoal.
Marine biologists explain that while lion's mane jellyfish typically grow up to 10 feet in body length, their tentacles can reach an astonishing 120 feet, making them one of Earth's longest animals. The sting from a lion's mane jellyfish, though exceptionally painful and described as the worst in the UK, is not dangerous to life. Experts recommend carefully removing any detached tentacle fragments with a stick and washing the affected area with warm water.
These jellyfish occasionally appear on the Welsh coast in late summer or autumn, with their primary UK habitat being Scotland. The diver who filmed the spectacle is also involved in a conservation project aimed at making aquatic environments more accessible and appreciated, emphasizing a non-harmful approach to documenting marine life.