You can’t deny it.
The question: do sharks like human blood? — takes you down memory lane.
Maybe a few images from the 2004 Chris Kentis’s ‘open waters’ must have popped into your head. Or famous images of sharks tearing up the deep blue sea’s characters.
We often get bombarded with movies about sharks’ undiluted craze for blood.
But in the real sense of it, do sharks like human blood?
We don’t think so. And we have evidence to prove that human blood might be the least attractive thing to sharks. So, before you take your scuba diving adventure to the next level, this article is a must-read!
We believe it’s time to disabuse some shark notions! Because they’ve got to be the most misunderstood animals in the world.
How Far Away Can Sharks Smell Blood?
The fear of sharks isn’t a rarity. If you ever claim you aren’t scared of sharks, you’ll probably get a weirdo tag on your forehead. Well, that’s hardly surprising.
The whole world believes sharks exist solely to tear humans to pieces. Sorry to tear down these illusions, but it’s not true. Same as the exaggerated ability of sharks to smell blood from miles away.
Now to the truth.
Sharks’ sense of smell is strong. How do sharks smell? They owe this acute ability to their nostril’s aka nares, located beneath their snouts. Since the nares only exist for picking scents, it might as well do an excellent job.
Their nares aid the shark’s detection of every minuscule quantity of any substance in the water.
Does this mean they can smell sharks from miles away? Or maybe a more accurate version of that question is: how far away can sharks smell blood?
There are about 500 species of sharks in the world. So, the sharpness of their sense of smell differs. A few sharks can pick a scent hundreds of meters away from the source. But this is a super ability reserved for some sharks.
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Imagine this for a moment.
You went surfing in Florida. Unfortunately, you sustained an injury. While struggling to minimize the blood gushing out, you remember the warnings about sharks. Fortunately, the closest shark zone seems to be a quarter-mile away from you.
Do you have to fear a black tail shark pouncing on you in a split second?
Don’t get us wrong.
Some sharks smell blood from a quarter-mile away. But it won’t magically get to them immediately. Scents ride the waves. Simply put, the scent of anything can only reach a shark through currents. And when the smell travels to them, it takes a while before it travels to their nostrils.
If you are familiar with the ocean’s currents, you understand that the motion varies. The ocean’s motion determines when and whether the scent would reach the shark– at all.
The faster the current, the quicker your scent travels toward or away from the shark.
So, if you happen to find yourself bleeding while surfing out the Atlantic in Florida, you have time to swim to safety. But let’s set the record straight.
The chances of sharks attacking you are almost non-existent. We agree that statistics show 54 unprovoked bites from sharks in 2020. But we seem to fear the wrong things. Mosquitoes kill more people in a day than sharks have done in a century!
Contrary to the cliché notion that sharks love human meat, sharks would pick fishes over humans– no offense. They are fussy eaters.
While shark species have different preferences, humans won’t make It to any’s menu list. Still, that leaves us with a vital question: are sharks attracted to human blood?
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Do Sharks Get Erratic at the Smell of Blood?
Sharks squirming frantically to get a taste of some human blood isn’t a challenging image to conjure. However, it’s another misconception. Sure, they can smell blood– which includes human blood. But they aren’t crazy about human blood.
We are sure that sharks probably believe we award our blood an undeserving credit (Just saying).
So, how do we explain the aggressiveness sharks display at the smell of blood in movies? The directors are in the best position to explain that. However, we can explain why we believe human blood doesn’t excite sharks.
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A daring– highly daring– experiment by Skyler Thomas of white shark studio company is video evidence. Thomas aimed to prove how aggressive sharks could get when they sense human blood. So, he cut his wrist slightly while surrounded by blacktip sharks.
Drum roll! Guess what happened?
The sharks weren’t impressed enough– or if they were, didn’t express it. Note that we’ve established that sharks possess an acute sense of smell. Hence, we are positive they didn’t miss the blood smell. But their strong sense picks up every scent in the water.
It means they could smell not only Thomas’ blood but every other thing in the water. So, they weren’t willing to drop something more exhilarating in pursuit of human blood– which is less exciting.
Of course, critics came for Thomas. They claimed he should attempt a similar experiment with more aggressive shark species.
Well, we haven’t seen a replay of that yet. However, we caught a rare video of a shark stopping to say ‘hi’ to the diver.
Fish Blood or Human Blood: The Shark’s Preference
So, are sharks attracted to blood? That’s almost like a trick question.
The short answer is: yes. Bloods can grab a shark’s attention– not necessarily human blood.
Are sharks attracted to human blood?
We have another convincing experiment to prove human blood is less appealing to sharks. An ex-Nasa engineer, Mark Rober, launched a captivating blood battle: fish blood vs. human blood. Rober experimented with cow blood and fish blood to discover which of these two a shark prefers.
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According to Rober, all-mammal blood smell the same way for sharks. Well, we’ve got to take his word for it. So, Rober dispensed the fish blood and cow blood around the same area but with some distance between them.
Based on this experiment, a bleeding fish is more likely to appeal to a shark’s cravings than walking human blood.
Well, that’s zero life expectancy to the fish world and a big plus to the humans.
How Can Sharks Smell Blood in Water?
Like we said earlier, sharks have a sense of smell, all thanks to their nares. They don’t breathe with their nostril (nares) like humans, but it ( their nostrils) contains sensory cells known as olfactory lamellae. The cells interrelate with particles from the ocean to discover even a mild concentration or whiff of scent announcing their prey’s presence. This smell ranges from blood to other organic particles.
Undoubtedly, sharks can smell blood. But that’s one of the numerous things they can detect.
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Blood scent is one of the numerous scents in the ocean. These scents include that of their favorite menu. For some sharks, it might be the smell of a sealion or bony fish.
Luckily, sharks’ sense of smell does more than identifying the scent; it’s sharp enough to lead them to the source. So, they don’t struggle to hunt down an already detected prey.
A prey’s smell or a blood smell travels in water to reach a shark’s nostrils. So, it takes a while before they perceive it- and that’s if the waves are in their favor.
Consequently, a shark’s ability to smell blood in water depends on its species and how far away the shark can smell a drop of blood.
Not all sharks have a keen smell sense. Some have an average smell ability.
How Can You Avoid Shark Attacks?
Let’s face it. Sharks still attack humans. Even though we aren’t on their food menu, we still need to be wary of their attacks.
International shark attack file’s report shows 57 unprovoked shark attacks in 2020. Whether by mistake or fear of imminent threat, sharks attack humans– and sometimes it’s fatal.
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How can you avoid a traumatic shark experience?
We’ve got some safety tips below:
- Don’t swim in water with many bait fishes– sharks eat fish, so bait fishes attract sharks.
- Avoid swimming at dusk, dawn, or night
- Sharks love lone preys; always swim in groups
- Except you are going scuba diving, swim close to the shores
- Avoid wearing silver or any shiny jewelry
- Leave the water if you sense the presence of sharks
- Water splashing attracts sharks– avoid it.
- Don’t wear highly contrasting colors because sharks are sensitive to bright colors.
- Avoid the temptation to touch a shark if you encounter one
- Don’t swim with your pet
- Get away from the shark if one ever attacks you
Sharks are predators. Humans are predators as well. While it’s better to avoid confrontations with sharks, hating them is unnecessary. We need to take precautions while in water. But forget the movies, and take it from us, sharks are not the bad guys.
Can Sharks Smell Fear?
Note that we didn’t claim a shark has a supernatural avenger-worthy nostril. So, no, sharks can’t smell fear. They have a sharp sense of smell.
But they can only smell anything that interrelates with the sensory cells embedded in their nares. And since fear can only interact with your emotions, sharks can smell fear.
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However, the sense of smell isn’t the only active sensory organ they wield while hunting. Sharks’ other abilities include the electro-sensing ability. With this ability, sharks can detect their prey’s heartbeat and movements.
Consequently, they can detect fear based on their prey’s movement and heartbeat rate.
Do Sharks Attack When They Smell Human Blood?
Human blood hardly attracts an attack from sharks, but a wounded fish will likely suffer the worst fate. To answer the question: does blood attract sharks? Yes, it does. But mammal blood is unlikely to attract them.
Besides the scent of fish blood, another thing that makes fish attractive to sharks is the electric signals their struggle sends when wounded.
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Hence, fishing in a shark habitat with harpoons is a dangerous move. It exposes the fisherman to attacks because the smell of fish blood is a potent bait for sharks.
You are probably wondering: why do sharks love blood?
Sharks aren’t blood-sucking predators that feast on blood. But the smell of their prey’s blood excites them because it means: food! Blood is a crucial indicator that announces their prey. With their poor eyesight, it’s no wonder that other senses like smell are sharp.
What Attracts Sharks?
Blood of their prey. The scent of a sea lion or seal’s blood would catch a great white shark’s attention faster than an amusement park piques’ a kid’s interest.
Although blood is primary, it’s not the only enticing thing to a shark. It appears that brightly colored clothing like yellow, silver, or white may seem like a beaconing lighthouse to a shark. Divers recommend dark-colored fins, tanks, and clothing for safety.
Can Sharks Sense Human Heartbeat?
If you are adventurous and enjoy scuba diving with sharks, you should be brave. Sharks hunt using their sense of smell and their sensitive electrosensory organs. Hence, they can detect their prey’s heartbeats and movements. Consequently, they can sense the human heartbeat as well.
How Do You React to Sharks Circling?
If you ever get stranded with sharks circling, you– as crazy as this would sound– need to stay calm. And try your best not to panic.
Sharks have acutely sensitive electrosensory organs capable of detecting sudden movements and heartbeat. So, don’t call any attention to yourself, but calmly swim to the shore if possible. Or swim toward anything that can keep you out of water.
Are Sharks Attracted to Period Blood?
No. Sharks are attracted to blood, but they won’t attack you because you are on your period. A shark can detect any bodily fluid in the water. However, no positive evidence suggests that period inspires shark attacks.
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But if you don’t want to take any risks, you could stay out of the water. Or better still, use tampons or a menstrual cup. Moreover, evidence shows that swimming water pressure stops your menstrual flow temporarily. It means the chances of your period flowing into water are low.
Has a Shark Ever Saved Human?
Funnily enough, sharks have saved humans in weird ways. Do sharks like humans? Well, not as food– but as buddies, we can’t tell! Maybe some do.
For instance, a man’s cancer was discovered after a shark attack. He didn’t have a reason to have a checkup before that attack. He even described it as a blessing– the shark attack saved led to early detection of cancer.
Another man who had been lost on the sea for five weeks almost missed a rescue boat! Guess who helped. A shark nudged him awake from his frequent drifts into unconsciousness.
Alas! There was a boat. The shark swam around the boat and swam off.
If sharks could speak, it would have probably said: “hey buddy! Wake up, time to go home.” The fisherman credits the shark with his rescue– we can’t agree more!
Even mosquitoes’ notoriety supersedes a sharks’! But life could be unfair– even to sharks.
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Shark isn’t out to get your blood. That’s a misconception that has tainted this predator’s reputation.
In reality, sharks can do without human blood, and they don’t catch a whiff of blood scent from miles away.
We hope that this has demystified the shark’s lifestyle a little. Human blood barely makes it to the shark’s scale of preference. But stay safe if you must scuba dive with sharks.
British-born Dan has been a scuba instructor and guide in Egypt's Red Sea since 2010.
Dan loves inspiring safe, fun, and environmentally responsible diving and particularly enjoys the opportunity to dive with sharks or investigate local shipwrecks.
When not spending time underwater, Dan can usually be found biking and hiking in Sharm's desert surroundings.