MythBusters Episode 235: MythBusters vs. Jaws

A scuba tank in a shark’s jaws will explode and destroy the shark if shot with a bullet. (A revisit of Scuba Tank Explosion based on the film Jaws.)

re-busted

Adam and Jamie chose to consider three issues raised by fans: the possibility that the tank might have exploded if only grazed by the bullet, the effect of different bullet calibers, and the chance of injury caused by the punctured tank rocketing down the shark’s gullet. Adam examined preserved shark specimens to understand their anatomical structures, and he and Jamie then built a shark analog; cowhide leather was used to simulate the esophagus and stomach, layers of carpet strips stood for the muscles, and an outer layer of painted upholstery foam was added as the skin.

Naming the shark Brewster, they placed it in a quarry pond and set a scuba tank containing 80 cubic feet (2,300 L) of air at 3,000 pounds per square inch (21,000 kPa) in its mouth. The bottom of the tank faced outward, and Adam shot it with a .30-06 rifle from 110 feet (34 m), to match the movie scene. Although the bullet punctured the tank, the air release drove it only a few feet down the gullet; it did not enter the esophagus, and Adam and Jamie reasoned that the shark might be able to expel it.

For their second test, they investigated the effect of a grazing impact, thinking that it could create a weak spot in the tank wall and lead to an explosion. Adam fired six shots at the side of the tank, all of which ricocheted away without effect; a seventh shot, with a .30-06 armor-piercing round, gave the same result. When Jamie shot the tank bottom with a .50 sniper rifle, it punctured and was propelled into Brewster’s body, bursting out near the tail. Another shot, to the side of the tank, also failed to burst it. Declaring the myth busted, they fitted a tank with a small charge of C-4 and set it off in Brewster’s mouth; the tank exploded with enough force to tear the head off and shred the body with shrapnel.

Sharks can be driven away from an area by the sound of orcas underwater.

busted

Adam and Jamie visited an area in the Bahamas where both sharks and orcas had been sighted. With Jamie observing near a shipwreck on the ocean floor, Adam lowered a box of chum into the water and played sounds through an underwater speaker. For a control test, a recording of humpback whales (not a natural predator of sharks) was used, and Jamie reported that the sharks were unaffected. A mixture of orca sounds was played for 10 minutes, including sounds associated with their hunting behavior, but Adam saw no change in the sharks’ behavior. He and Jamie classified the myth as busted.

The smell of a dead shark can repel live sharks.

confirmed

Adam and Jamie obtained a concentrated liquid sample of the aroma compounds present in dead sharks and set up a new experiment in the Bahamas. They hid a box of chum on the ocean floor to attract sharks and went underwater. Jamie released the repellent as Adam watched from a distance; the sharks quickly left the test area and did not begin to return for nearly 6 minutes. No other fish in the area showed any visible reaction.

They repeated the test in a different location, with Jamie and the underwater camera crew feeding the sharks to bring them to the edge of a frenzy. When he released the repellent, they quickly fled the area and did not begin to return for nearly 5 minutes. Adam and Jamie judged the myth as confirmed, and Adam noted that the repellent had not been made from any of the shark species observed in either test.