Blue Jellyfish Swarm Covers Jeju Beach, Surprising Swimmers

Recently, swarms of blue jellyfish have been spotted at various beaches in Jeju, prompting warnings for swimmers.

On the 27th, numerous social media posts reported sightings of blue jellyfish along Jeju's coast. According to the posted photos, these blue jellyfish were seen resting on the shore as well as floating in the water.

A citizen who witnessed the scene testified, "While swimming, I was startled to see what looked like blue mold floating in the sea. Lifeguards quickly instructed people to exit the water and cleared the jellyfish, so there was no harm done."

Characteristics of the Blue Umbrella Jellyfish and Safety Measures

It is reported that the jellyfish retrieval operation was conducted swiftly and concluded in about 30 minutes.

Experts have identified the jellyfish that covered the beach as the "Blue Umbrella Jellyfish." This species is known to be oceanic, believed to have originated from the open sea before flowing into the coastal waters of the Republic of Korea, and is typically observed from July to August in the southern sea area.

The Blue Umbrella Jellyfish has a head diameter of about 3 to 4 cm, with tentacles (polyp) hanging beneath its head.

A distinguishing feature from other jellyfish is that its umbrella part is composed of chitin. While it is not highly toxic, it can cause stinging sensations or rashes upon skin contact, so it is advisable to avoid touching it if possible.

This incident is an example of the recent frequent occurrences of Blue Umbrella Jellyfish in the waters around Jeju.

On the 22nd, a swarm was reported at Sagye-ri Beach in Andeok-myeon, Seogwipo City, and on the 23rd, Blue Umbrella Jellyfish were also sighted at Pyoseon Beach in Seogwipo City, leading to temporary restrictions on access to the area.

Image source: Blue Umbrella Jellyfish / National Fisheries Research Institute