Former Cronulla Fisheries Research Centre scientist Dennis Reid identified the one metre long intruder as a Blind Shark, which frequents rocky shallows.

“It’s not dangerous, but it can latch on to an arm or leg with a vice-like grip and can often only be released by decapitating the shark,” Mr Reid said.

“Had it got Melissa’s arm, she would have been thinking, ‘How the hell can I get this off?’“

Mr Reid worked at the Cronulla fisheries centre from 1974 until 2011, initially for the CSIRO and then for the NSW Department of Primary Industries.

He is semi-retired and still active in the field.

Mr Reid said the Blind Shark was from the Carpet Shark family, which also included the Wobbygong.

“The eyelid is retracted when the shark is out of the water, hence the name,” he said.

“They are very hardy and can survive out of the water for at least 18 hours.”

Mr Reid said G P Whitley, who published The Fishes of Australia in 1940, noted the naturalist in the First Fleet identified this shark in Sydney waters

“They are quite common in shallow areas such as rock ledges, caves, tidal pools etc around rocky headlands,” he said.

Mr Reid provided newspaper reports of previous nasty incidents involving Blind Sharks that were smaller than the one picked up by Ms Hatheier.

“They would have weighed about  one kilogram, whereas the one at Oak Park would have been 7-8 kilograms,” he said.

In 2004, a 60 centimetre long shark attached itself to the leg of a spear fisherman at Caves Beach, near Newcastle.

The man had to swim 300 metres to shore, and said he started to sink three or four times before making it to the beach.

He then walked to his and drove to the surf club, with the shark still clinging to his arm.

Lifeguards considered using pliers or bolt cutters to prise the shark free, before opting for a dose of fresh water.

This caused the shark to start to choke and open and close its gills.

It tried to release the man’s arm, but he still had to prise open the shark’s mouth because its teeth were embedded in his skin.

The man was left with an injury, which he described as “similar to a large love bite”.

In 2001, a Bondi man was snorkelling at the southern end of Bronte beach when a blind shark latched on to his arm.

When the shark could not be removed, a lifesaver got a knife and cut off its head.

Mr Reid said the Blind Shark was born at 17 centimetres, become adults at 60-66 centimetres and grew to a maxim of about 120 centimetres.

“Their teeth are about two milimetres long,” he said.

”When sharks get into rock pools they are most likely Blind Sharks.

“This would happen only a few times in a decade, but sometimes you wouldn’t know.

“They would come in on the high tide  and go out on the next one,” he said.