Researching the intelligence of the grey bamboo shark a team of researchers at Rheinische Friedrich-Wilhelms-University in Bonn, Germany showed that sharks could be trained to recognise and remember shapes for an extended period of time.

First juvenile sharks were subjected to three different cognition experiments, one at a time, and then tested to see how long the sharks could remember their training.

Florida again led the United States in shark attacks last year, with 28 incidents and no fatalities. The vast majority of the Florida incidents were minor ones in which a shark quickly bites an arm or leg in poor visibility water, releasing it as soon as the shark realizes its prey isn't a fish.

"Most of them are better called bites than attacks," said George Burgess, curator of the International Shark Attack File. "They're the equivalent of dog bites."

The five types of shark were among 21 species of shark and ray, including sawfish, granted new protection status at a convention summit in November.

Although Australia did not object to the listings in November, it is now seeking to opt out of the commitment to cooperate with other countries to ensure the five migratory shark species do not become extinct. The expanded list is due to come into effect on 8 February.