Bill Haast figured he had handled more than three million poisonous snakes over the years, and he had the hands to prove it.

An eastern diamondback rattlesnake left one hand looking like a claw. A Malayan pit viper mangled an index finger. A cottonmouth bit a finger, which instantly turned black, prompting his wife to snip off the fingertip with garden clippers.

Mr. Haast was bitten at least 173 times by poisonous snakes, about 20 times almost fatally. It was all in a day’s work for probably the best-known snake handler in the country, a scientist-cum-showman who made enough money from milking toxic goo from slithery serpents to buy a cherry-red Rolls-Royce convertible.

A secret of his success was the immunity he had built up by injecting himself every day for more than 60 years with a mix of venoms from 32 snake species. He suspected the inoculations might have explained his extraordinarily good health, but he was reluctant to make that claim, he said, until he reached 100.