Quote Originally Posted by Soapets
I heard on the news that the stingray's stinger went directly into his heart. Usually they're not fatal otherwise, just extremely painful. But the injury to the heart itself was probably fatal, even without the stingray's poison that was injected into his heart.
Yes.

The stingray was buried in the sand and Irwin must have startled it. He accidently boxed it in. Quick movements or motion towards to stingray can cause them to attack, but they are normally not aggressive creatures at all.

Their barbs are like a knife with teeth on both sides.. that going through the front of his chest would definitely be a fatal blow. It caused him to go into cardiac arrest. He was killed moments after the blow.