I posted my thoughts on the other thread, but I had to find out what it was that killed Steve!
Irwin, 44, collapsed after being stung through the heart at Batt Reef, near the resort town of Port Douglas, about 1,260 miles north of Brisbane, police said. He was filming an underwater documentary when the accident occurred.
http://www.guardian.co.uk/australia/story/0,,1864423,00.html Here's pic of a stingray's barb:

History:
- Stingrays commonly are found lying half-buried in the sand or mud of coastal temperate areas.
- Injuries tend to occur when an unsuspecting person steps on the fish, causing the animal to reflexively strike the person with its defensive mechanism.
- The stingray's tail has 1 or more barbed stingers and 2 ventrolateral venom-containing grooves that are encased in an integumentary sheath. The tail is thrust into the victim, usually in the foot or lower leg, producing a deep jagged laceration from the serrated spine(s).
- The stinger apparatus then injects a protein-based toxin into the wound, causing immediate intense (even excruciating) pain in the victim. Injury may occur without envenomation because many stingrays lose or tear the integumentary sheath covering the venom glands.
Physical:
- The wound may bleed freely and the patient may have systemic symptoms, including the following:
http://www.emedicine.com/EMERG/topic556.htm In the heart! How awful!