Movies such as Jaws, Open Water, and The Meg have long contributed to the shark’s bloodthirsty killer reputation.
Many people are terrified of sharks, often having nightmares of these ocean dwellers and unable to relax around shark inhabited waters.
We’ve all heard the rumor that sharks are able to smell blood from miles away, and will go into a frenzy if they smell so much as a drop.
Today, we’re going to take a closer look at this myth and answer a question that often comes up when discussing sharks. Are sharks attracted to blood?
No, sharks are not attracted to blood. Whilst they can detect blood in the water, it’s not going to send a shark into a frenzy and prompt an attack. They are barely interested in human blood at all and much prefer fish blood.
Do Sharks Attack When They Smell Blood?
Sharks have some of the most effective senses in the animal kingdom. They use a different sensory system when hunting in order to detect their prey.
Blood can be one indicator that leads a shark to its prey, and if they’ve already been hunting this animal then they will most certainly attack when they catch up to their prey.
That said, human blood isn’t something that sharks are interested in. Just because they are able to smell and detect your blood, doesn’t mean they’re going to come charging toward you and attack.
Most shark attacks are a result of sharks mistaking humans for prey, and once they attack and realize that what they thought was a large fish or seal is a human, they’ll typically back off.
Due to environmental damage and other factors, sharks are now being forced into coastal waters where it’s common for them to encounter humans.
This leads to more attacks as humans and sharks are coexisting in the same space, but the reason behind the attacks still remains the same.
How Do Sharks Smell Blood In The Ocean?
Sharks have special nostrils that they use for only smelling, they are called nares. The nares contain a lot of sensory cells that are called olfactory lamellae.
The cells interact with the particles in the ocean, allowing the sharks to detect even low concentrations of odors that might indicate prey.
This includes blood and the many other smells that come along with life in the ocean. Blood is not the only odor that sharks smell.
They can also smell their favorite prey, and they’ll often follow the scent for miles until they eventually catch up with it.
A trail of blood makes it easier for sharks to find their prey, but the scent still needs to travel through the water to reach the shark in order for them to smell it.
The length of time it takes for sharks to detect blood depends on the species, as well as the amount of blood in the water.
Some species of shark are better at sensing blood than others whilst other abilities may be weaker, it all depends on the species as to how well sharks can detect blood.
How Far Can Sharks Smell Blood In The Water?
Under perfect conditions, sharks can smell blood from a quarter-mile away, but it takes time for the blood to travel through the water to reach them.
It also depends on the current of the water as well as the species of the shark, in most cases, they need to be a lot closer than a quarter-mile to detect blood.
As we now know, sharks rely on tiny particles entering their nares to detect scents. They have extremely sensitive nostrils and are able to detect scents from far away.
Particles from different scents disperse differently in the water. That said, depending on what it is, they can detect things in the water at between 1 part in 25 million and 1 part in 10 billion.
To put that into perspective, that’s around one drop of blood per Olympic-sized swimming pool.
However, it’s not only the number of particles that plays a role in how far sharks can detect scents. It’s also the current of the water and the amount of blood.
If an animal has just been killed and there is a lot of blood pouring out into the ocean, sharks will be able to detect this much faster than if there is only a couple of drops of blood.
Do Sharks Smell Fear?
Whilst sharks have exceptional sensory organs that allow them to detect prey easily, they are unable to smell fear.
Sharks are unable to smell feelings, but it’s worth noting that sharks also have an electro-sensing ability that allows them to detect the heartbeat of prey as well as their movements.
This means that they can sense if their prey is panicking as their heart rate will increase, signaling to the shark when to attack.
Whilst they can’t smell fear, they may well be able to detect it by the electrical impulses that are given off by someone who has an accelerated heartbeat due to fear.
This means the calmer you stay in the water and around a shark the better, as they know that you’re not afraid and are not prey.
Easier said than done…
Are sharks attracted to blood? No, not particularly. Whilst they are able to detect blood in the water, it doesn’t necessarily attract them to the scene.
Human blood is not of interest to sharks, but fish blood on the other hand can signal to sharks that there is prey around that may be worth seeking.
They have an exceptional sense of smell that allows them to detect blood from up to a quarter-mile away in optimal conditions.
However, it’s important to note that this depends on the species of shark as well as the current and amount of blood in the water.
Thanks for taking the time to read this post and learn more about how sharks detect blood in the ocean.
If you have enjoyed this article, feel free to stick around to learn more about sharks and the many other types of marine life that we discuss here.
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Hi, I’m George – the founder of MarinePatch. I created this blog as marine wildlife has been my passion for many years and I’ve spent decades learning and dedicating myself to documenting all I can about the topic.