Venice Beach, Fla., and the sun is hot and strong. Most tourists are simply lounging on the sand turning various shades of furious red or "Baywatch" bronze. A few are chucking Frisbees or checking out the babes.

Here and there, though, are individuals wandering around with their eyes fixed firmly on the ground, seemingly oblivious to their subtropical surroundings.

These guys aren't here for suntans or babes. Like us, they're here for the teeth of the biggest shark ever to have cruised the oceans; Carcharodon megaladon, known to aficionados as "Big Meg."