The Ultimate Sharks and Magnets Quiz

By: Staff

4 Min Quiz

Image: refer to hsw

About This Quiz

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.

Which of the following have been sold as shark repellants?

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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Tonic immobility is a condition that occurs when a fish lies on its:

Tonic immobility is a temporary paralysis that naturally occurs when a fish lies on its back.

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What happens when you drop a magnet in the water near a shark?

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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When you mix salt water and charged metals, you get a weak electrical:

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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The special pores located around the snouts of many shark species are called _____ of Lorenzini.

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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Electrical impulses are carried through the _____ in the salt water in the ocean.

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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Sharks can sense changes in underwater electrical fields through their ampullae of Lorenzini. Stronger electric fields caused by _____ may overwhelm their senses

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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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.

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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What is the major problem with Eric Stroud's invention that uses magnets to repel sharks?

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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Sharks are known to pursue their prey single-mindedly. How might this influence the effectiveness of a magnetic shark repellant?

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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What percent of the world's sharks are on the verge of extinction?

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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SharkDefense suggests using electropositive metals on _____ in an attempt to keep sharks away from commercial fishing bait.

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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Which company is studying the feasibility of using magnetic fences to keep sharks away?

Ocean Magnetics, an offshoot of SharkDefense, is studying the feasibility of using magnetic fences to keep sharks away.

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During which war did the United States Navy seek to develop an effective shark repellant?

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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During the 2000 Summer Olympics in _____, Australia, divers wore gadgets called Protective Oceanic Devices (PODs) to ward off sharks.

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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