<p>Stingrays are considered passive creatures, but their venom and their barbed tails can be deadly, experts say.</p>
<p>Even so, fatal attacks such as the one that killed television star and naturalist Steve Irwin are extrenely rare.</p>
<p>Irwin, 44, died today when a spear-like stingray barb pierced his chest while diving on the Great Barrier Reef, and it's believed he may have had a heart attack.</p>