Several innovative companies around the world have developed devices based on the idea of repelling sharks with magnets. Do they work? Check out our quiz and learn more about sharks and magnets.
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Question 2 of 16
Which of the following have been sold as shark repellants?
sunscreens
disguises
both of the above
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Though various companies have touted special sunscreens, chemical sprays, visual tricks and disguises as shark repellants, there is little proof that any of these things really work.
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Question 3 of 16
Tonic immobility is a condition that occurs when a fish lies on its:
right side
left side
back
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Tonic immobility is a temporary paralysis that naturally occurs when a fish lies on its back.
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Question 4 of 16
What happens when you drop a magnet in the water near a shark?
Nothing happens.
The shark swims away.
The shark jumps out of the water.
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In studies conducted with sharks at the Bimini Biological Research Station in the Bahamas, when researchers dropped a magnet in the water near a shark, the shark swam away.
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Question 5 of 16
When you mix salt water and charged metals, you get a weak electrical:
field
zone
area
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When you mix salt water and charged metals, you get a weak electrical field. When a shark comes close to that field, the field seems to disrupt the sharks' special sixth sense, known as electroreception.
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Question 6 of 16
The special pores located around the snouts of many shark species are called _____ of Lorenzini.
nostrils
pores
ampullae
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Many shark species have pores located around their snouts called ampullae of Lorenzini, which can detect changes of up to one-billionth of a volt of electricity in the seawater.
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Question 7 of 16
Electrical impulses are carried through the _____ in the salt water in the ocean.
ions
neutrons
electrons
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Electrical impulses, coming from the muscle contractions of other aquatic life forms, are carried through the ions in the salt water in the ocean.
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Question 8 of 16
Sharks can sense changes in underwater electrical fields through their ampullae of Lorenzini. Stronger electric fields caused by _____ may overwhelm their senses
sound waves
radio waves
magnets
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We know that sharks can sense changes in underwater electrical fields through their ampullae of Lorenzini. Stronger electric fields caused by magnets, may overwhelm their senses and cause them to run away.
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Question 9 of 16
Which company applied for a United States patent for installing Lanthanide electropositive metals into scuba flippers and other items to act as a shark repellant.
SharkProtector
SharkDefense
SharkAway
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In 2007, Eric Stroud of SharkDefense applied for a United States patent to install Lanthanide electropositive metals into scuba flippers, a bracelet and a belt to act as a shark repellant.
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Question 10 of 16
What is the major problem with Eric Stroud's invention that uses magnets to repel sharks?
You would need too many magnets.
The sharks will eat the magnets.
The magnets will fall off in the water.
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The magnetic field in Eric Stroud's invention deters sharks up to only about a foot (30 centimeters) away. You would need many magnets for them to be effective and the weight of the additional metals could make it hard to swim.
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Question 11 of 16
Sharks are known to pursue their prey single-mindedly. How might this influence the effectiveness of a magnetic shark repellant?
The sharks will definitely back off.
The sharks will never back off.
The sharks will possibly back off.
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When sharks are hungry enough, they will probably continue to pursue their prey in spite of anything, including an uncomfortable electrical field created by magnets.
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Question 12 of 16
What percent of the world's sharks are on the verge of extinction?
20 percent
30 percent
40 percent
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According to the World Conservation Union, 20 percent of the world's sharks are on the verge of extinction. Commercial fisheries accidentally hook and net millions of sharks each year.
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Question 13 of 16
SharkDefense suggests using electropositive metals on _____ in an attempt to keep sharks away from commercial fishing bait.
fishing hooks
fishing nets
fishing lines
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SharkDefense suggests using electropositive metals on fishing hooks in an attempt to keep sharks away from commercial fishing bait. For their idea, SharkDefense was awarded the 2006 grand prize from the World Wildlife Fund's International Smart Gear Competition.
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Question 14 of 16
Which company is studying the feasibility of using magnetic fences to keep sharks away?
Sea Magnetics
Shark Magnetics
Ocean Magnetics
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Ocean Magnetics, an offshoot of SharkDefense, is studying the feasibility of using magnetic fences to keep sharks away.
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Question 15 of 16
During which war did the United States Navy seek to develop an effective shark repellant?
World War I
World War II
the Vietnam War
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During World War II, the U.S. Navy developed a substance to coat its underwater torpedoes that would stop sharks from bumping into them and setting them off prematurely.
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Question 16 of 16
During the 2000 Summer Olympics in _____, Australia, divers wore gadgets called Protective Oceanic Devices (PODs) to ward off sharks.
Melbourne
Sydney
Brisbane
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During the 2000 Summer Olympics in Sydney, Australia, during the swimming portion of the triathlon, divers wearing devices called Protective Oceanic Devices (PODs) formed a protective border to ward off sharks. The POD generates a weak electrical field designed to overwhelm a shark's electroreception sense.
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