MythBusters Episode 102: Shark Week Special 2

In shark-infested waters, a person can reduce the their chance being attacked by playing dead.

confirmed

To test this myth, the MythBusters traveled to the Bahamas and attracted several sharks by chumming the ocean water. Tory and Grant then donned protective chain mail and entered the water, floating a short distance from each other. The two took turns thrashing about and playing dead. Each time, the sharks were clearly more attracted to the person who was actively thrashing.

(This myth was based on real stories of survival from Navy sailors aboard the USS Indianapolis in 1945. The cruiser was torpedoed near the Philippines, stranding some 900 sailors in the water for 4 days. Of the 317 men who survived, several attributed their survival to playing dead when sharks were near.)

In the frenzy of a shark attack, a person can successfully find and gouge the shark’s eyes in an attempt to repel it.

plausible

Adam and Jamie built a life-sized fiberglass shark for this myth. The shark had an articulating body to simulating thrashing and pneumatic jaws with 90 serrated, removable steel teeth. It also featured eyes made of rubber buttons, which shut the shark off when pressed. As a test subject, they used Tory, who knew the shark could be shut off, but he supposedly did not know how. It took Tory about 15 seconds of thrashing in the shark’s jaws to shut the shark off. Adam also got in the jaws, upside down, and struggled to reach the eyes. The team called this myth “plausible”, noting that a person’s success with this method of defense would depend on the particular circumstances of the attack.

During a nighttime dive, flashlights will attract sharks.

confirmed

This myth is based on the idea that the electromagnetic field created by flashlights may attract sharks. The MythBusters first performed a control dive to see how many sharks appeared at night when they dove without flashlights. When they tried diving with flashlights, significantly more sharks appeared in a shorter amount of time and the sharks behaved more aggressively toward the flashlights.

Magnets are effective for repelling sharks.

busted

This myth is based on the fact that sharks have sensory organs called ampullae of Lorenzini, which are capable of detecting electromagnetic fields. The MythBusters tried several experiments to test the deterrent power of magnets. First they used a young, captive nurse shark. A handler immobilized the shark by turning it upside down. Jamie then brought a magnet near the shark, and it bent away from the magnet. When the shark was upright, it bent away strongly and tried to escape from the handler. The MythBusters also used a sheet of plastic to hide the approaching magnet from the shark’s vision. In this condition, the shark tried to bite at the magnet through the opaque sheet when the magnet was brought near. Next, another nurse shark was used for a different test. The shark was in a small pen, and the a row of magnets was used to divide the pen in half. The shark would not swim over the magnets, but it would swim over a line of steel chunks used as a control. Finally, the MythBusters covered fish-filled bait boxes with strong neodymium magnets and submerged them in waters infested with wild, adult lemon sharks. These sharks attacked the boxes aggressively regardless of whether there were magnets on them. This myth was declared “busted” because the magnets did not work for all species of sharks nor when there was food present.

Chili peppers are an effective shark repellent.

busted

Adam and Jamie puréed dozens of habanero chilies and used the resulting paste to fill balloons. These balloons were attached to bait boxes and were submerged in the ocean. Adam was planning to pop the balloons with a pneumatic needle but the sharks took the initiative and attacked the balloons. The sharks that bit the balloons did not show any sign of discomfort or repulsion, and the other sharks and fish swimming through the cloud of chilies were not repelled.

The chaotic paddling and the scent of a dog will attract sharks.

busted

The build team created a robotic dog complete with fur, barking speakers, and paddling legs. The dog was also equipped with syringes that could deploy dog urine, dog blood, and dog anal gland secretion. None of these elements attracted any sharks.

The sound of a flapping fish will attract more sharks than if the fish was stationary.

plausible

Adam and Jamie used plastic fish cut-outs shielded by screens, so that only the sound would be available to the sharks. There was some increase in shark activity, but not enough to be especially notable until the screen was removed and the sharks could see the fish. Adam and Jamie agreed that the sound of the fish flapping can get the sharks’ interests up initially but additional stimuli is needed to hold that interest.

Mini-Myth: Sharks can see and will attack food that is above the surface of the water.

confirmed

The MythBusters attached shark bait to the end of a stick and held the bait a few feet above the water. The sharks repeatedly emerged from the water and took the bait.

(This mini-myth was based on a seen from the movie Deep Blue Sea in which shark jumps out of water and catches a pet parrot.)