How a Passive Stingray Can Become Deadly

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From LiveScience:

Stingrays like the one that killed “Crocodile Hunter” Steve Irwin are cousins of sharks. But unlike some sharks, which are fearsome predators with powerful jaws, the stingray is rarely a threat to humans and its small mouth is no threat at all.

The tail of the stingray that killed Irwin is capped with a roughly 8-inch spear made of the same stuff that makes up shark scales, known as dermal denticles. The spear, which stiffens when the stingray feels threatened, is serrated like a steak knife and packs a venom that can be deadly to predators…

Irwin was likely killed not by the sting so much as the fact that the stingray’s spear pierced his heart and caused him to bleed to death, according to news reports.