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Top 10 Misconceptions About Nature’s Efficient Killers: Sharks

by Jonathan H. Kantor
fact checked by Jamie Frater

Ever since Jaws hit theaters, folks have feared stepping into the water for fear of becoming a giant fish’s snack. The book and films paint sharks as evil killing machines, which couldn’t be further from the truth.

Sharks rarely harm people, and they don’t ride around in tornadoes as much as people think. Still, there are tons of misconceptions about nature’s most efficient killing machines, and these ten are easily the most widespread.

10 Facts That Will Change How You View Sharks

10 Sharks Are Nature’s Most Efficient Killing Machines

GoPro: Freediving with Tiger Sharks in 4K

Don’t let the title fool you; sharks arent nature’s best killer. That honor doesn’t even belong to the vertebrates! Viral organisms have held that particular trophy on their collective mantles for as long as they’ve been hopping rides in animals’ bodies only to return the favor by killing them.

To be fair, many sharks are efficient predators, but that doesn’t make them nature’s most efficient killers. Many sharks are intelligent and calculating — they stalk their prey in the same way a pride of lions might plan a hunt.

They wait patiently for the perfect moment to strike, which is why you often see sharks swimming peacefully around their potential “food.” Sharks that hunt their prey often rely on surprise and will abort their attempt if that advantage is lost.

Of course, this only applies to some shark species, and there are probably more than you might know. More than 500 species of shark have been identified, and some are more efficient at hunting than others. Many species are far less discerning and will attempt to eat anything they come across.

9 Sharks Are Maneaters


Sharks are scary because they look terrifying. Add to that the fact that they are often unseen when they attack people, and you have nothing short of terror on everyone’s minds when one is sighted. Because of this and movies that capitalize on fear, sharks have been labeled as “maneaters.”

The vast majority of sharks spend their entire lives without ever seeing a human. Think about it for a second — Earth’s oceans are enormous, and most people only venture into the waters along coastlines, leaving a massive space for sharks to swim without seeing people.

The vast majority of shark species are opportunistic feeders that primarily eat small fish and invertebrates. Only around 12 species have been involved in attacks on people. When it does happen, it’s usually due to the shark mistaking a human for something else.

Granted, when a shark bite does occur, it’s serious. Just a little chomp is enough to cause massive tissue damage, the mangling of limbs, and death if not treated right away. The seriousness of these incidents helps give rise to the “maneater” myth, but in the end, that’s all it is.

8 Sharks Are At The Top Of The Food Chain

GoPro: Orca Rescue in 4K

Most people think of sharks as nature’s most efficient killing machines, but we’ve already dispelled that myth. Still, the myth prevails, leading many to assume that sharks are at the top of their respective food chain.

It makes sense when you think about it… what could possibly pose a threat to a shark? Technically, humans kill far more sharks than anything in the ocean, but we aren’t exactly members of their food chain. As it happens, while sharks don’t have to live in constant fear of many predators, they are hunted in their environment.

When most people picture the deadliest shark, they probably think of the Great White. After all, they can grow up to 23 feet (7 meters) and weigh 2.5+ tons or more. They can become prey to larger great whites, but the creature that hunts and eats them is the aptly named Killer Whale.

This behavior was first documented in 1997 when two Orcas attacked a Great White shark to consume its liver. Since that time, more attacks have been witnessed, proving there’s a predator the largest predatory sharks fear.

7 Sharks Can’t Get Cancer

Do Sharks Get Cancer? | Cancer Research UK

Because cancer has long been one of humanity’s deadliest enemies, people have looked to other animals to try and find a means of fighting it. Over the years, this has manifested in many ways. The most perplexing is the belief that sharks are so evolved that they are somehow immune to cancer.

This is entirely false, as malignant tumors have been found in sharks since the first was identified in the late 19th century. It likely became popular because, while sharks can (and do) get cancer, it’s somewhat rare when compared to other animals. As a result, people have long believed that grinding up shark cartilage and consuming it will prevent/kill cancer (it doesn’t).

Another culprit for this myth is the 1992 bestselling book, Sharks Don’t Get Cancer: How Shark Cartilage Could Save Your Life. In the book, I. William Lane and Linda Comac explain that sharks rarely get cancer. The book promotes using their cartilage for health benefits.

It also endorsed a product from one of the author’s sons, eroding its credibility as legitimate scientific research. Regardless, the myth prevails despite the large body of scientific evidence proving otherwise.

6 Sharks Will Die If They Stop Swimming

Why Do Sharks Have To Keep Swimming?

There has long been a belief that sharks need to swim to live, which is associated with how sharks breathe. Like most fish, sharks breathe via gills, which extract oxygen from the water as it passes over them. Unlike most species of fish, sharks do this in a variety of ways.

Some species use ram ventilation, which works when they swim fast with their mouths open, forcing water to flow through their gills. Typically, when a shark is breathing in this manner, they swim faster than usual and are always moving.

Some sharks use buccal pumping, which works by drawing water into the mouth and over the gills, which they can do while remaining completely still. This has been observed in Bullhead and Nurse Sharks.

The Tiger shark has been known to switch between buccal pumping and ram ventilation, depending on their need. Some species lost the ability to buccal pump, including Great Whites and Mako Sharks. These “obligate ram ventilators” will indeed stop breathing if they don’t swim, so the myth isn’t true of nearly every species of shark but does apply to a few.

5 Sharks Can Detect A Single Drop Of Blood From Miles Away

Testing if Sharks Can Smell a Drop of Blood

You’ve probably heard this at some point in your life, and ever since, you’ve taken precautions to avoid the water with even a tiny cut. Many sharks are hunters, and they do have an acute sense of spell and a sensitive olfactory system, but it’s not a supernatural ability.

Sharks use their nostrils entirely for smelling since they can’t breathe through them. They are lined with incredibly sensitive cells capable of picking apart various chemicals interpreted as smells by the brain. While this translates into an accurate sense of smell, it doesn’t extend for miles in any direction.

Some sharks have been known to detect a low concentration of something at a few hundred meters, which is hardly a mile or more. Some species of sharks can detect specific compounds at 1 part per billion, which sounds impressive — and it is — but it amounts to about 1 drop in an average-size swimming pool.

Sharks can definitely pick apart a scent in a large body of water, but it’s limited far more than the myth allows. This ability isn’t restricted to predation either, as it comes in handy when detecting pheromones emitted during mating.

4 Sharks Can Swim Backward

For the vast majority of fish species, swimming backward is as simple as flicking the pectoral fins in the right direction. This makes it possible to quickly escape from danger, and most fish can do it, though not as well as they can swim forwards.

Because this isn’t much of a problem for most fish, it stands to reason that people would believe that sharks can swim backward. Oddly enough, sharks are among the minority of fish species that cannot swim backward, and it’s to do with several factors of their anatomy.

Sharks swim forward by moving their tails to push water around their fins, which they use to stabilize and steer their bodies. Unlike most fish, their pectoral fins don’t curve upwards, limiting their swimming to forward movement only. When a shark moves backward, it does so by stopping movement and letting gravity do the rest.

Moving backward can actually be harmful to sharks due to their need to move water over their gills to breathe. Backward movement can lead to suffocation in some species, so doing anything but swim forward isn’t an option.

3 Sharks Are Only Found In Saltwater

Bull Sharks Upriver | National Geographic

Ask just about anyone in the world what kind of water sharks call home, and they’ll describe oceans. This makes sense, seeing as most sharks are found in the world’s oceans, but there are some exceptions.

There are six species of River Sharks found in Southeast Asia, South Asia, New Guinea, and Australia. These sharks all fall under the genus Glyphis, and they all reside in freshwater for their entire lives. Unfortunately, most species of River Sharks are largely unknown to science.

This is due to severe population decline due to habitat degradation, making them some of the rarest sharks in the world. Little is known about their lifecycle and populations as a result of their diminishing numbers. Often, River Sharks are confused with another freshwater-loving species, the Bull Shark.

Bull Sharks spend most of their lives in freshwater, but they return to the ocean to mate. They travel the world’s rivers and have been found as far inland up the Mississippi River as Alton, Illinois, which is about 1,750 miles from the Gulf of Mexico. In 1972, one was found 2,500 miles up the Amazon River, so they do just fine in freshwater.

2 All Sharks Are Deadly To Humans

Caribbean Reef Sharks | SHARK ACADEMY

Many people around the world wrongly assume that sharks are maneating predators capable of causing severe harm or death. While it’s true that a shark bite is almost always a serious injury that can lead to death, the belief that all species of sharks are capable of causing harm to humans is simply false.

Only about a dozen species of sharks have ever been known to bite humans, and seeing as there are around 500 species known to science, that’s only about 2.4% of all sharks. That leaves hundreds of different species that are of no threat to people, and the variety of these animals is pretty amazing.

Some sharks, like the Caribbean Reef Shark, are dangerous to humans if they attack, but they rarely do. Still, you wouldn’t want to get bitten by one. Nurse sharks are well known for having no interest in people whatsoever, and while attacks are incredibly rare, disturbing them might cause a bite.

The largest shark and largest fish in the world, the Whale Shark, is of no danger to humans. They are filter feeders, so it has no interest in people at all. If you found yourself in its mouth, it would be almost as upset as you, but seeing as it lacks any teeth in its mouth and would spit you out, you’d walk away with the best fish story ever told.

1 Sharks Can “Go Rogue” And Hunt Only Humans

Do Rogue Sharks Exist?

The term “rogue shark” is often used to describe a shark that stops hunting its usual prey and instead seeks out and subsists entirely on people. This is, of course, unnatural for all the reasons previously mentioned.

So-called “rogue sharks” are blamed for shark attacks on people, but the concept of a “rogue shark” is entirely without merit. Sharks don’t suddenly gain a taste for humans and seek them out. typically, when a shark bites someone, they realize it isn’t their typical prey and move on.

They rarely take a second bite, though it can sometimes happen. Ultimately, it’s easy to see that rogue sharks aren’t a real threat if you look at the number of annual shark attacks. Globally, 57 unprovoked shark attacks were recorded in 2020. Ten of those resulted in fatalities, and 33 occurred in the U.S.A.

That may seem like a lot, but the odds of a person being bitten by a shark are incredibly low. Your odds of being attacked by a shark are 1 in 3,748,067. You are more likely to be struck by lightning before winding up in a train accident and ultimately dying from fireworks long before succumbing to a shark attack.

Top 10 Fascinating Facts And Stories About Sharks

fact checked by Jamie Frater
Jonathan H. Kantor

Jonathan is a graphic artist, illustrator, and writer. He is a Retired Soldier and enjoys researching and writing about history, science, theology, and many other subjects.

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