Unidentifiable jellyfish discovered at Cronulla raises fear it could be fatal

An unidentified breed of jellyfish that has striking similarities to a deadly species has been sighted near a popular family beach.

Scott Belcher spotted the 30 centimetre long jellyfish swimming 800 metres from the shore at Shelly Beach at Cronulla, south of Sydney, on Sunday.

Its structure has stumped experts who have been left scratching their heads trying to determine if it’s a new species or cross between several breeds.

Mr Belcher believed the sea creature may have been a southern box jellyfish known as a Jimble. 

Scott Belcher spotted the 30 centimetre long jellyfish swimming 800 metres from the shore at Shelly Beach at Cronulla, south of Sydney, on Sunday

The structure of the jellyfish has stumped experts who have been left scratching their heads trying to determine if it’s a new species or cross between several breeds (pictured, Cronulla beach)

The jellyfish have a body length of five centimetres, tentacles spanning 25cm and a sting likened to a ‘cattle prod’.

The unidentified species appears to be much larger with a body length of 10 centimetres and tentacle span of 20 to 30cm. 

Fears were raised it could have potentially been a variation of the fatal northern box jellyfish scientifically labelled Chironex fleckeri.

The species is considered to be the most venomous sea creature and has claimed the lives of 60 swimmers in Australia.

The jellyfish enjoy swimming in warm coastal waters and are commonly found in the Indo-Pacific region and northern Australia.

Their bodies can grow up to 38cm wide and their tentacles up to three metres.  

Launceston biologist Dr Lisa-ann Gershwin reassured swimmers the unidentified creature was not a northern box jellyfish.

She was not ready to rule it out as deadly and said it could be a cross between the Chironex fleckeri and Chiropsella saxoni.

Dr Gershwin described the jellyfish as a ‘mysterious critter’ and said she was excited by the prospect of it being a new species. 

The unidentified species appears to be much larger than the Jimble with a body length of 10 centimetres and tentacle span of 20 to 30cm

Launceston biologist Dr Lisa-ann Gershwin reassured swimmers the unidentified creature was not a northern box jellyfish

‘It actually looks like it might be venomous, but it may not be dangerous,’ she told Daily Mail Australia.

‘It definitely has venom, but whether it can kill two people is yet to be seen. That’s the part we care about the most.’

Dr Gershwin advised it was better for swimmers to keep their distance until it could be determined if the jellyfish was venomous.

‘There are two ways of finding out if it’s venomous: someone can get stung, or we can test it,’ she said. ‘We would much rather prefer to test it, rather than find out by accident.’ 

Dr Gershwin admitted she has not yet thought of a name for the jellyfish.

‘The two questions I want to know is, who is it and how dangerous is it?’ she said.

‘It’s amazing in this day and age with so many people in the water and go, “oh my god, I don’t know what this is”.’