Sept. 5, 2006 — -- Stingray barb deaths like the one suffered by Steve "Crocodile Hunter" Irwin are extremely rare, experts say.
Australian experts estimate that there have been between 17 deaths and 30 deaths worldwide over the last decade or so.
Irwin's is the third known death in Australia.
Many beach-goers have come in contact with stingrays, and zoos and aquariums often let people -- from children to senior citizens -- feed and touch them.
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Stewart Clark, a vice president of Discovery Cove at SeaWorld in Orlando, Fla., says stingrays are not aggressive animals.
They prefer to swim away from humans rather than confront them.
The stingray thought to have killed Irwin is known as a "smooth" or "bull ray," among the largest stingrays in the world.
According to eyewitnesses, the one that stung Irwin was about 8 feet long, more than 200 pounds, and probably would have had a barb about 8 inches long.
Irwin reportedly was swimming directly above the ray, with a cameraman in front.
The ray apparently felt threatened, plunging its barb into Irwin's torso.
The autopsy report on Irwin has not been released.
Many experts, including Clark, believe the barb probably ripped a hole in Irwin's heart or other vital organs, which some say would be like being stabbed with a bayonet.
Other experts say, however, that his quick death was probably the result of an allergic reaction to the venom, which sent Irwin into cardiac arrest.
A stingray's barb is sharp, with a serrated surface like a bread knife.
In most cases, the barb stays stuck in the victim's flesh as the ray swims away because it's a lot easier to insert a serrated object than to withdraw it.
At SeaWorld and other venues, the barbs on rays are clipped.
In the Caymans, a locale known as "Stingray City" draws 100,000 visitors a year and the stingrays' barbs are not clipped.
The venom is contained in a slime that covers the barbs.
The sting is immediately painful and grows even worse over time.
The venom, however, moves relatively slowly.
In the few instances in which humans were killed by the venom, it sometimes took days.
Being hit near a vital organ with venom -- as Irwin was -- is much worse than catching it in the leg or foot, where 90 percent of stingray strikes occur.
People who have been barbed by a stingray in the foot say the pain is excruciating; some women have said that it was worse than childbirth.
There are at least 1,500 reported stingray injuries every year in the United States. The actual number of injuries is almost certainly higher.