The 12-year-old lad could have lost both his feet if he was not wearing shoes after the beast sank into jaws into him.
The frightening attack occurred when the youngster was on holiday with his parents Debbie, 48, and Jim, 56, and his brothers Kyle, nine, and Jamie, 14.
They were staying with his uncle in
and had jet skiing off the Bahaman island of Bimini.
He scrambled back to the dock but within seconds the fearsome creature pounced.
Suddenly he saw a “shark’s body rise out of the water” and “shouted for help” before feeling the marine animal brush against him.
“I didn’t really realise I got bitten by a shark until I actually managed to climb up the ladder, and I saw my shoes, and they had a big hole in them, torn on the sides,” he said.
After being rushed to hospital, Shane needed 20 shots of anaesthetic and 53 stitches to heal the massive puncture wounds and lacerations.
His mum arrived minutes after the bite to see the blood on her son and his injuries.
“‘I just keep thinking what could have happened.
“He could have lost his feet or legs, or been killed.”
The brave young Scot, who loves wildlife and David Attenborough programmes, has however not been put off by the experience and still hopes to become a marine biologist in later life.
Heartstopping footage recently showed a jet skier surrounded by 15 aggressive bull sharks.