Steve Irwin killed

Marine experts say television personality and naturalist Steve Irwin had little chance of surviving after being struck in the chest by a stingray's barb.

Forty-four-year-old Irwin died this morning in far north Queensland while filming for a marine documentary.

Sea World's marine science director Trevor Long says stingrays have killed a total of 17 people worldwide.

"All of those fatalities have occurred in the trunk of the body," he said.

"Many people, many fishermen have been stung by sting rays in the feet and the hands and it's not an unusual occurrence but it doesn't cause a great deal of problem.

"It's a venom - a protein-based venom - that can affect the heart."

Friends of the man known as the "Crocodile Hunter" say he died doing what he loved doing best.