Tourists were surprised to find thousands of jellyfish washed ashore along Bo Yai Beach in Cha Am, Phetchaburi, this week.
Local fisheries officials have confirmed the incident is a natural annual phenomenon linked to strong monsoon winds and waves — and have advised people not to touch the jellyfish for safety reasons.
According to Phetchaburi Provincial Fisheries Officer Prachuap Jiangyee, the species is the Catostylus mosaicus, commonly known as the jelly blubber. It has mild venom that is not life-threatening, though people with sensitive skin may experience mild irritation if they come into contact with it.
Natural phenomenon driven by strong winds
Officials said the jellyfish were discovered along more than a kilometre of coastline in Bang Kao Subdistrict, Cha Am. Most appeared intact, while some had begun to dry out under the sun. The mass stranding was likely caused by strong southwesterly monsoon winds and waves pushing the jellyfish towards the shore over recent days.
“This happens every year, especially along the eastern coast of the Gulf of Thailand — from Ban Laem and Mueang Phetchaburi through to Cha Am,” Prachuap said. “There’s no reason to be alarmed, but people should avoid direct contact to prevent stings or skin irritation.”
Jelly blubber jellyfish not dangerous
Jelly blubber jellyfish are gelatinous, dome-shaped creatures with short tentacles. They are sometimes processed for food in parts of Asia as they are high in protein and low in fat. However, officials warn against handling them as a precaution.
Prachuap added that more dangerous jellyfish, such as box jellyfish, can be easily recognised by their bright colours and long white tentacles. Their sting can cause severe pain and, in extreme cases, can be fatal. If stung, it’s important not to rinse with fresh water but instead to use seawater or vinegar and seek medical help immediately.
Fisheries officials will continue to monitor the coastline as strong winds and currents are expected to persist throughout the week.