Stingrays Poisonous, but Rarely Kill Humans

Steve Irwin fell victim to extraordinarily bad luck to be killed Monday by a stingray, a bizarre-looking but normally shy creature whose defenses include poisonous serrated barbs in the tail, experts said.

At least 35 species of stingrays swim in the tropical waters of the Great Barrier Reef, where Irwin died after being stabbed in the heart in what experts said was a freak accident.

Usually the triangular-shaped beasts are unobtrusive, gliding through the water on their wide, flat bodies, rummaging on the sea bottom for food or burrowing into the sand which their skin is often toned to match.

But when frightened or stepped on, vicious-looking spines up to 10 inches long with breadknife-like serrations are deployed as a defense mechanism.

"If it's spooked by someone stepping on it or swimming too closely over it, frightening it, the tail raises involuntarily," said Victoria Brims, a marine life expert at OceanWorld, an aquarium in Sydney.

The spines emit toxins that can kill many animals and which cause excruciating pain in people. Few die from the poison, but the hacking injuries caused be the spines can badly tear flesh, and the wounds are prone to infections, including tetanus.

Simon Pierce of Queensland University's School of Biological Sciences said there were no accurate records of stingray deaths, but there had been about 30 worldwide in recent years.

Experts agreed Monday that Irwin's death — he was struck directly in the heart, witnesses said — was extremely unlucky.

"It was extraordinarily bad luck," said Shaun Collin, a University of Queensland marine neuroscientist. "It's not easy to get spined by a stingray, and to be killed by one is very rare."