When Australian surfer Kai McKenzie was attacked by a shark off Port Macquarie in New South Wales one week ago, his leg was bitten off.

The 23-year-old survived by catching a wave to shore, where an off-duty police officer helped him by applying a tourniquet to his bleeding leg using a dog leash. His severed leg washed up and was put on ice by locals to save it.

McKenzie and the leg were flown to a Newcastle hospital where doctors hoped to reattach the leg. A few days later, however, McKenzie revealed that the leg was not reattached, BBC reports.

Nevertheless, the surfer was thankful to all the people who worked to save him and donated money for his costly hospitalization.

For other traumatic limb injuries, an arm or leg may have to be amputated to prevent life-threatenening infection. American researchers revealed cases of injured limbs being bitten off to prevent death.

The researchers observed in a laboratory that if an injury suffered in a fight or caused by a predator was further up the leg of a female Florida carpenter ant (Camponotus floridanus), nest mates bit it off. Losing one of its six legs still leaves an ant fully functional.

When the injury was further down the limb, the wild worker ants did not amputate it. Instead, the reddish-brown bugs cleaned the wound using their mouths, Japan News reports.

“In this study, we describe for the first time how a non-human animal uses an amputation on another animal to save their life,” said entomologist Erik Frank of the University of Wurzburg in Germany, lead author of the research published on 2 July in the journal Current Biology, according to Japan News.

Frank added that amputations are done on injured worker ants so they would survive and continue to be productive members of the colony.