Venomous box jellyfish spotted in Gulf of Mannar

A marine researcher, who was stung by a jellyfish in June, told TNIE that he suffered severe pain for a week. “It left a black scar on the face,” he said.
A swarm of jelly fish found at Motagopuram between Threspuram and Vellapatti during 2020 in Thoothukudi.
A swarm of jelly fish found at Motagopuram between Threspuram and Vellapatti during 2020 in Thoothukudi.(File photo | Express)

THOOTHUKUDI: Among a bloom of jellyfish sighted along the coast of the Gulf of Mannar, box jellyfish of the species Chironex indrasaksajiae, notorious for causing fatalities, were spotted. Meanwhile, researchers of the Central Marine Fisheries Research Institute (CMFRI) have taken the specimen for research purposes. 

Although jellyfish sightings are common along the coasts in Thoothukudi, Tiruchendur and other east coast areas, people raised alarm over its consequences. According to local fishers, jellyfishes of Lobonemoides sp (Chen soari), Cephea sp (Ana soari), Chrysaora sp (Vaal soari), Acromitus sp (Mutta soari),Ceyanea (Aluva soari), and others are sighted off the east coast but cause limited issues like itching, nausea and pains, whereas Physalia physalis (Kaka soari) and Chironex sp (Naalu mukku soari) are dangerous.

A marine researcher, who was stung by a jellyfish in June, told TNIE that he suffered severe pain for a week. “It left a black scar on the face,” he said.  Meanwhile, another researcher said he was stung on his neck, and suffered from fever for a day. While jellyfish produce toxins, just about 2% of jellyfish toxins are harmful to humans, say marine biologists. 

According to Dr R Saravanan, Senior Scientist, Marine Biodiversity Division at CMFRI, Mandapam region, Indian coastal waters have jellyfish belonging to 212 species of Hydrozoa, 37 species of Scyphozoa and five species of Cubozoa, while TN’s coasts have 14 Scyphozoans and two Cubozoans. Jellyfish play a vital role in controlling zooplankton and small fish, he said.

Senior CMFRI scientist Dr Ranjith told TNIE that the box jellyfish belonging to Cubozoa, Physalia or Hydrozoa are fatal enough to cause death. “I had been searching for the jellyfish species causing fatalities since 2016. Four persons had died along the coast of the Gulf of Mannar and the adjacent Palk Bay,” he recalled.

Saravanan says a specimen of a box jellyfish was collected during a survey at Dhargavalasai, along the Palk Bay coast in 2021, and analysis revealed that it was Chironex indrasaksajiae, having 12 tentacles in each pedalia. “No jellyfish of genus Chironex was documented before in Indian waters,” he said.

The Chironex indrasaksajiae was discovered off the Gulf of Thailand in 2017, while Chironex fleckeri was discovered in Australia in 1956 and Chironex yamaguchii in 2009 in Japan, he added.

A research paper authored by R Saravanan, L Ranjith, S Thirumalaiselvan, I Syed Sadiq and K Vinod, published in 2023, confirmed the expansion of Chironex indrasaksajiae from its primary area to Indian waters. Ranjith said the jellyfish washed ashore due to winds, water currents and other factors.

When stung by a jellyfish, researchers say dousing the area with vinegar neutralises the sting and minimises pain.

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