Free Diver Captures Rare Footage of a Giant Lion’s Mane Jellyfish ‘the Length of a Bus’ as Species Shift North

A rare encounter with a lion’s mane jellyfish off the coast of Wales has sparked discussions about the implications of climate change on marine life. Iestyn Morgan, a 21-year-old freediver from Pembrokeshire, encountered the jellyfish while swimming near Trefin Beach. Measuring an astonishing 10 to 15 metres (approximately 33 to 49 feet), the jellyfish is an unusual sight in Welsh waters, raising questions about the species’ changing habitats.

Morgan described his experience as surreal, noting that it was the first time he had ever spotted a lion’s mane jellyfish in Wales. As he glided through the water, he initially saw a few tentacles drifting around him, which soon multiplied. “Three turned to ten, and then to twenty,” he recounted, sharing his astonishment with the BBC. His excitement was evident, especially as the tentacles appeared to stretch endlessly. He initially mistook the creature for a compass jellyfish, a more common species in the region, until realising the scale of the animal before him.

The lion’s mane jellyfish is distinguished by its long, flowing tentacles, which are instrumental in capturing prey. Marine biologist Dr Cathy Lucas from the University of Southampton explained that while the jellyfish’s bell can reach up to 3 metres, its tentacles can exceed 30 metres, making it one of the longest living creatures on Earth. Lucas highlighted that Morgan’s footage effectively showcased this remarkable length, emphasising how even the tentacles can be difficult to detect due to their fine structure.

Although the stings from a lion’s mane jellyfish are known to be painful, Dr Lucas reassured the public that they are not life-threatening. She described the sting as potentially being “the worst in the UK.” For those unfortunate enough to come into contact with a tentacle, Lucas advised using a stick to remove it and rinsing the affected area with warm water.

Historically, lion’s mane jellyfish are primarily found in the cooler waters off Scotland. However, their occasional appearances in Welsh waters are increasingly becoming a topic of interest, particularly in regards to climate change. Morgan noted that he has observed a rise in the number of warm-water species along the Welsh coast, specifically mentioning the surge in triggerfish, typically native to Mediterranean regions.

This local observation aligns with broader scientific findings that marine heatwaves are becoming more common as a consequence of climate change, leading to a shift in marine biodiversity. Researchers believe that these conditions may benefit warm-water species while placing pressure on those adapted to cooler waters, such as the lion’s mane jellyfish.

Morgan’s passion for marine wildlife extends beyond just personal encounters; he actively films marine life to increase public awareness of environmental threats and to foster ocean conservation. He clarified, “I just get in the water, film, and swim,” emphasizing his commitment to advocating for the seas without causing harm to any creatures he captures on camera.

With ongoing changes in marine ecosystems, encounters like Morgan’s may become more common as species adapt to shifting water temperatures. As such, these extraordinary wildlife sightings are not just fortunate events; they are a reminder of the urgent need to address the broader challenges posed by climate change on marine environments. Morgan’s extraordinary experience highlights the delicate balance in ecosystems and the necessity for increased public awareness and action to protect these vital underwater habitats.