STINGRAYS are placid fish that attack rarely, usually only when frightened.
They are, nevertheless, formidable fighters, with a long, venomous barb at the end of their powerful tails. It is this that gives them their name.
The apparent candidate for Steve Irwin’s fatal encounter is the smooth stingray, Dasyatis brevicaudata, the biggest known stingray and one known for causing savage lacerations to divers who get too close. The serrated 12in (30cm) barbs are usually used to fend off predators such as killer whales. A ray has the option of squirting venom.
Bryan Fry, deputy director of the Australian Venom Research Unit at the University of Melbourne, said: “Stingrays only sting in defence. They’re not aggressive animals so the animal must have felt threatened.”
Sean Connell, a marine ecologist from the School of Earth and Environmental Sciences at the University of Adelaide, said: “I have never heard of an unprovoked attack from a stingray. Such attacks usually only happen when the ray is under severe stress.”
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Short-tail stingrays can reach more than 4.3 metres (14ft) in length, weigh more than 350kg (772lb) and prey on crabs, mantis shrimps and conger eels, but would not usually be expected off the northern coast of Queensland.
There are 43 other varieties of stingrays in Australian waters, 11 of which are found on the Great Barrier Reef; eight of them are big enough to kill a human being.