The octopus is one of planet earth’s most alien-like creatures. They have large heads with super-intelligent brains, eight appendages, and are formidable predators.
They can be found in all five of the world’s oceans, often searching coastal marine waters in search of food such as crabs, snails, and small fishes.
Octopuses are well known for their eight tentacles that are covered in suction cups which allow them to hunt prey, but they’re also known for their unique anatomy.
Today, we’re going to take a closer look at the octopuses’ organs, and answer a question that often comes up when discussing these interesting cephalopods. How many hearts does an octopus have?
Octopuses have three hearts, one which pumps blood around the body whilst the other two pump blood to the gills. Their three hearts pump blood around the octopus’s boneless body to supply oxygen and support their lifestyle.
Do Octopus Have Three Hearts?
Yes, octopuses do have three hearts. Many species of octopus live in the deep ocean where the water is cold and there is less oxygen available.
This is why octopuses have evolved to have three hearts, to help transport sufficient oxygenated blood to all parts of their body in this cold environment.
Two hearts pump blood to the gills, whilst the larger of the three hearts focuses solely on taking oxygenated blood and circulating it to the organs and around the rest of the body.
Why Do Octopuses Have Three Hearts?
Octopuses are part of the cephalopod family, along with squids, cuttlefish, and nautiluses.
The word cephalopod literally means “head foot”, which is rather accurate when you picture any of these animals.
Like the other members of the family, octopuses have blue blood because it uses a copper-rich protein to transport oxygen, which helps explain why they need three hearts.
For us humans, our red blood gets its color from an iron-based protein known as hemoglobin, which is carried in our red blood cells.
Cephalopods use a copper-based protein called hemocyanin, which is much larger and circulates in the blood plasma.
Hemocyanin is less efficient at binding with oxygen than hemoglobin, but octopuses compensate for this by having three hearts.
Hemocyanin also seems to help transport oxygen efficiently in environments that vary widely in temperature and oxygen levels.
It’s particularly efficient in the cold ocean, in places like Antarctica. However, hemocyanin loses its ability to bind to oxygen as acidity increases, which doesn’t bode well for octopuses as climate change makes the oceans warmer and more acidic.
The hemocyanin also makes their blood thicker, which means that they need their three hearts in order to create more pressure to pump blood to and from the gills and around their body.
Octopuses have two branchial hearts that are located near each of the animal’s two gills and focus only on pumping blood to the gills.
They then have a third heart known as the systemic heart that pumps oxygenated blood to the rest of their body.
Each of the octopus’s hearts is equally as important, all working together to keep the octopus alive and transport blood around the body and keep blood flowing to the gills.
These hearts are required to supply the octopuses’ muscles with oxygen, which they need when walking along the sea bed hunting or escaping from predators.
Do All Octopus Have Three Hearts?
Yes, all octopus species do have three hearts. Each heart carries out a specific function and are all equally as important as one another.
If an octopus somehow loses one of its branchial hearts, it will still be able to survive with just two hearts.
An octopus has one heart near each of its two gills that pump blood through its gills, if one of these drops off then it would be similar to a human losing a lung.
Humans can survive with one lung, and although it’s not optimal and performance would drastically reduce, like a human, an octopus would survive.
However, if an octopus lost its systemic heart which is the larger of the three and pumps blood all around the body, the octopus would not be able to function and die.
Why Do Octopuses Habe Blue Blood?
The mystery behind why octopuses have blue blood is a key part of understanding their need for three hearts.
As mentioned earlier, octopuses use hemocyanin in their blood, which is heavier than the hemoglobin that is in our human blood.
Octopi have proven to be incredibly efficient at using up all of the oxygen their hearts pump through their body, which may be a result of necessity instead of a sign they have an efficient circulatory system.
Hemocyanin is only about a quarter as effective as hemoglobin at transporting oxygen, making it important that octopuses have three hearts with two specialized circulations and one for processing.
Studies into an octopus that lives in the coldest ocean on earth could shed some light on why these animals have such a seemingly inefficient protein in their blood.
Pareledone charcoti (Antarctic Octopus) displays considerably higher concentrations of hemocyanin in its blood, around 40% more than any other octopus on earth.
Is this a coincidence? I think not…
Researchers believe that this physiological change is meant to help these octopi adapt to colder conditions where oxygen exchange rates are much less efficient.
These octopi were still able to adapt to adjust and even exceed their circulatory efficiency when they were placed in warmer waters.
There are over 300 different species of octopus on earth, and they’ve managed to make a home in almost every body of seawater.
These highly adaptable animals have evolved to survive in the harshest of conditions with freezing cold temperatures which their strange heart combination could be to thank.
So how many hearts does an octopus have? Three, two branchial hearts are located near the gills to pump blood to them, and one systemic heart to pump oxygenated blood around the body.
Octopuses have evolved to have three hearts largely because many species live in cold waters and have thicker, blue blood.
Three hearts provides more pressure which helps to pump this blood around the body effectively and provides their bodies with oxygen to keep them alive.
All three hearts of an octopus are incredibly important, and it’s not like they have an extra heart as a substitute waiting for one to give in before it starts working.
All hearts work at the same time and are crucial for the octopuses’ survival. If they lose a branchial heart then they may survive, but if their systemic heart fails then they are as good as dead.
Thanks for taking the time to read this post and learn more about one of the most fascinating animals on planet earth.
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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. I’ve spent over a decade in the marine wildlife industry and spent years out in the field conducting research. In today’s modern world, an online blog is the best place for me to share my findings and reach as many people as possible to help educate and inspire others. Enjoy your time here and you’re welcome back anytime!