In the year 2021, a box jellyfish specimen was gathered during shore-seine operation at Dhargavalasai (Fig. 1&2) coast during the regular survey along the Palk Bay shore in Tamil Nadu. Upon examination at the Mandapam CMFRI facility, it was discovered that this specimen had volcano pedalia canals with 12 tentacles in each pedalia, matching the description of the species Chironex indrasaksajiae, which was discovered in the waters of the Gulf of Thailand in 2017. The genus Chironex has never been documented before from Indian seas. The discovery of a potentially fatal species of box jellyfish in Palk Bay verifies that it exists, at least along India's east coast. With up to 15 tentacles on each corner of its body and a potential combined tentacle length of over 60 metres, Chironex fleckeri is a big jellyfish that can reach a maximum size of 30 cm. Because of its transparent body, it is rarely seen before venoming a victim.
Many deaths have been caused by the extremely venomous genus Chironex in tropical and subtropical coastal regions across the globe. The most well-known of them, Chironex fleckeri, has been linked to fatalities in Australia. There have been fatalities in Japan and most likely the Philippines due to C. yamaguchii. Much about the behaviour and ecology of Chironex, and cubozoan jellyfish in general, is still unknown despite their widespread recognition.
Severe lower back and abdominal pain, constant nausea and vomiting, cramps and spasms throughout the body, trouble breathing, excessive perspiration, nervousness, twitchy muscles, migraines, and a sense of imminent death are the usual symptoms of Irukandji syndrome (Williamson et al., 1996). In addition, a lot of sufferers’ report having a creepy skin feeling, shivering, chattering teeth, coughing and/or grunting involuntarily, and, in some cases, priapism in men. Sometimes, severe hypertension poses a serious risk to life.
The most well-known box jellyfish that are frequently held responsible for fatalities are those belonging to the genus Chironex (Thaikruea et al. 2015). Southcott (1956) gave the first description of the genus Chironex for a single species, Chironex fleckeri, from Australia. Then, 53 years later, Lewis and Bentlage (2009) identified and named Chironex yamaguchii, another deadly species of Chironex from Japan. The year 2017 saw the description of the third species of Chironex (Chironex indrasaksajiae) by Sucharitakul et al. This study confirms the expansion of the species distribution from its primary area of description. In Figure. 3, a fisherman shows his hand with severe sting scar by box jellyfish of the possible Chironex species.