A Great White Shark is believed responsible for killing a South African swimmer.
Great white shark was not eaten by a mystery monster. Reuters

The truth behind the great white shark thought to have been devoured by a giant mystery monster of the deep has been revealed by scientists.

The 9ft (2.8 metre) shark was the subject of the Smithsonian documentary Hunt for the Super Predator, which made headlines worldwide last month.

Experts had been tracking a shark off the coast of Western Australia when it suddenly disappeared. The tracking device washed up four months later and analysis revealed it had experienced a huge temperature change, from 7C to 25C in just a few seconds.

Scientists said this could only have happened if the shark had been eaten by another creature, with the device ending up in the stomach of the mystery predator. Some suggested a huge unknown creature could be to blame -- filmmaker Dave Riggs said the notion of gigantism was "plausible".

However, CSIRO, which made the tracking device, has now provided an explanation. "The temperature recorded... was consistent with that of the core body temperature of a white shark but too low for something like a killer whale," CSIRO said.

"At one point, the tagged shark dived to a depth of 570 metres -- this is not unusual for white sharks -- it is normal behaviour.

"This dive took place about one week prior to the tag recording the higher temperatures (not immediately before as some have reported) and the two events are not related.

"We have seen white sharks biting each other before, sometimes removing pieces of tissue in the process. One shark bit off a little more than he could chew and ended up swallowing the tag.

"We never concluded that the 3m shark was consumed by another much larger shark. And that folks, is the truth."