How Many Hearts Does An Octopus Have? - OctoNation

Octopuses have three hearts: two branchial hearts that pump blood through the gills, and one systemic heart that circulates oxygenated blood throughout the body. But here’s the wild part, that systemic heart stops beating every time the octopus swims! That’s why octopuses prefer crawling, swimming literally exhausts their circulatory system. And that’s just the beginning. Their blood is blue (copper-based, not iron-based like ours), which is why they need three hearts in the first place, blue blood is less efficient at carrying oxygen, so they need extra pumping power to compensate. Let’s break down what each heart does and why this design is actually brilliant!

Quick side quest: Kind of like how an octopus has one main circulatory heart and two hearts that pump blood through the gills, they’ve also got a weirdly wonderful thing going on with distributed brain power. Wanna see how that works? Peep this: how many brains does an octopus have?

So, how many hearts does an octopus have?

Well, there is one main heart called the systemic heart, which acts much like our own heart pumping blood throughout the body. In addition, octopuses have two branchial hearts, which pump blood through their gills, all of which are located in their mantle.

The bulbous sac, usually behind the octopus’s eyes, houses all the important organs such as their:

• Gills
• Stomach
• Reproductive organs
• And, their hearts!

How Does an Octopus Circulatory System Work?

Octopuses have a functionally closed circulatory system, which is rare among mollusks. Their blood flows through a network of arteries, veins, and fine capillary-like vessels instead of sloshing around in open body cavities like most of their relatives. Blood travels in a continuous loop, and all three hearts work together to keep it moving.

Here’s the play-by-play:

1. Deoxygenated blood returns from the body. After delivering oxygen to muscles and organs, blood heads back toward the gills carrying waste like CO₂.

1. Branchial hearts take over. Each of the two branchial hearts (one per gill) pumps that tired blood through a gill, where gas exchange happens. Oxygen in, carbon dioxide out.

1. Systemic heart distributes the goods. The oxygenated blood flows to the systemic heart, which sends it coursing back through the body to fuel all that arm intelligence and camouflage wizardry.

Why “functionally closed” instead of just “closed”? Researcher Schipp (1987) found that cephalopod blood vessels have an incomplete endothelial lining, unlike the continuous vessel walls in vertebrates. So it’s not a perfectly sealed system, but it’s close enough to generate the high blood pressure that makes octopuses among the most active, fast-moving invertebrates in the ocean!

The whole system works kind of like a relay race: branchial hearts hand off to the systemic heart, which hands off to the body, which hands back to the branchial hearts. Rinse, repeat, survive. And it all happens while their blue, copper-based blood does its best to keep up with the oxygen demands of one of the ocean’s busiest, and squishiest creatures. (squishy photo attached as evidence below)

Where Are an Octopus’s Hearts Located?

All three octopus hearts are tucked inside the mantle, that bulbous sac behind the octopus’s eyes that also houses the gills, stomach, and reproductive organs. The two branchial hearts sit at the base of each gill, positioned to pump deoxygenated blood directly through the gill tissue. The systemic heart sits more centrally in the mantle cavity, where it receives freshly oxygenated blood from the gills and sends it out to the rest of the body.

This central location is actually why the systemic heart stops during jet propulsion. When the mantle contracts hard to blast water through the siphon, that squeeze compresses the veins feeding into the systemic heart from the outside. Picture squeezing a straw shut. Nothing flows through, and the heart pauses until the pressure releases.

The branchial hearts, positioned closer to the gills themselves, keep chugging along even during those powerful contractions. They’re the oxygen pickup crew, and they never clock out!

Why Does the Octopus Heart Stop Beating When Swimming?

Here’s the thing about swimming as an octopus: your heart literally stops.

When an octopus needs to make a quick escape, it uses jet propulsion. Water fills the mantle (the big muscular sac behind the octopus’s eyes), then gets blasted out through a tube called the siphon. WoOhOo! Instant rocket mode!!! But there’s a cardiovascular catch…

A 1987 study in the Journal of Experimental Biology confirmed it: the systemic heart, the one responsible for delivering oxygenated blood to the arms, organs, and brain, arrests (stops) completely while the octopus is jetting. The two gill hearts (branchial hearts, one per gill) keep going, cycling blood through the gills. But the heart that sends that oxygen-rich blood to the body? That ticker is clocked OUT.

Wondering why? Picture the veins draining blood back toward the heart like straws feeding into a pump. When the mantle contracts hard to fire that jet, it pinches those drainage channels (called venous sinuses) shut from the outside. Ya squeeze a straw closed and nothing gets through, no matter how hard the pump pulls.This is exactly why octopuses usually crawl along the seafloor on their arms. Crawling keeps all three hearts beating steadily!

Jet propulsion for the octopus is the emergency escape button, not the daily commute.

Do All Octopus Species Have 3 Hearts?

Short answer: Yes. Every single one of them.

The three-heart system is universal across the approximately 300 known octopus species, regardless of size. And the size range here is absolutely shocking!

On one end: Octopus wolfi, the star-sucker pygmy octopus. Barely 2.5 cm (about an inch). Weighs less than a gram. Three hearts. On the other end: the giant Pacific octopus (Enteroctopus dofleini), the world’s largest octopus, typically 3–5 m (9–16 ft) in total length and known to exceed 180 kg (396 lb), with a mantle at least ~60 cm (2 ft). Also three hearts,

Every octopus runs the same cardiovascular setup: two branchial hearts (one per gill, think of them as the pickup crew collecting freshly oxygenated blood from the gills) and one systemic heart (the delivery driver sending it out to the body). Doesn’t matter if the octopus fits on your thumbnail or takes up your entire living room. Same system!

The only cephalopod that breaks the pattern? The nautilus, which runs a two-heart circulatory setup. But nautiluses are also the only living cephalopods with an external shell, so they were already doing things differently.

Can an Octopus Survive Without One of Its Hearts?

No. An octopus cannot survive the loss of any of its three hearts. Each heart plays a specialized, non-redundant role in circulation (meaning each heart is doing a job that isn’t easily covered by the others). The two branchial hearts pump blood through the gills to collect oxygen, while the systemic heart distributes that oxygenated blood to the body. Lose one of two gill (branchial) hearts and oxygen intake collapses. Lose the systemic heart and oxygenated blood never reaches the organs, arms, or brain.

LongER answer: keep readin’.

Unlike some animals that can compensate for organ damage, octopuses have zero cardiovascular redundancy. Humans can survive with reduced heart function. Some reptiles have three-chambered hearts that can reroute blood flow if one chamber fails. Starfish can regrow lost arms, and of course octopuses can regrow lost arms too, but their hearts? All three hearts are essential, and there’s no “Plan B.”

The two branchial hearts sit at the base of the gills, where each one pumps deoxygenated blood through a single gill to pick up oxygen. Think of them as the intake valves. Without them, blood never gets oxygenated in the first place. The systemic heart takes that freshly oxygenated blood and pushes it out to the entire body: eight arms, all the internal organs, and that big beautiful donut-shaped brain wrapped around the esophagus.

If the systemic heart stops permanently (not just the temporary pause during jet propulsion), oxygen delivery shuts down. Game over. 👾

Three hearts might sound like overkill until you learn how each one is absolutely essential.

Why Do Octopuses Need Three Hearts?

Octopuses need three hearts because their copper-based blue blood is thicker and less efficient at carrying oxygen than our iron-based red blood. Two branchial hearts pump blood through the gills to pick up oxygen, while one systemic heart circulates that oxygenated blood to the body. More pumps equals more pressure, which is exactly what thick blood needs to keep moving.

Here’s the thing: octopus blood looks blue because it uses hemocyanin, a copper-containing protein that transports oxygen. When hemocyanin binds to oxygen, the copper turns it blue (just like iron makes our hemoglobin-based blood red). But there’s a catch. Hemocyanin carries oxygen way less efficiently than hemoglobin in warm, oxygen-rich environments.

Think of it like trying to water your garden with a half-pressure hose. You’d need extra pumps to get the water to the far end of the yard, right? Same principle here, except the yard is eight arms, three hearts, and a donut-shaped brain wrapped around an esophagus. (Yup, can you imagine all your food passing through your brain on the way to your stomach? Too cool!)

So why use hemocyanin at all if it’s so inefficient? Because in the cold, low-oxygen waters of the deep sea, hemocyanin actually outperforms hemoglobin. Species like the dumbo octopus thrive in freezing, oxygen-poor depths precisely because their blood chemistry is optimized for those conditions. What looks like a disadvantage on a tropical reef becomes a serious survival advantage 3,000 feet down.

The system works like this: the two branchial hearts receive deoxygenated blood returning from the body. As blood passes through the gills, it dumps carbon dioxide and loads up on oxygen (same basic gas exchange that happens in our lungs). Those branchial hearts then push that freshly oxygenated blood to the systemic heart, which sends it coursing out to the arms, organs, and that big beautiful brain.

Three hearts, blue blood, and a circulatory system that’s been perfected over hundreds of millions of years. Pretty cool if ya ask us!

OctoNation is a nonprofit. Everything we publish is free because we believe octopus education should be accessible to everyone. If this article taught you something new, consider supporting our mission.

🐙 Octopus Fun Fact

Did you know there’s a heart condition named after an octopus trap? Tako is Japanese for Octopus. Takotsubo cardiomyopathy or “broken heart syndrome” comes from the name of a pot which Japanese fishermen would use to trap octopus.

The condition occurs when the heart muscle becomes suddenly weakened or stunned by severe emotional or physical stress.

Takotsubo cardiomyopathy is a temporary heart condition that develops in response to an intense emotional or physical experience. It’s also known as stress cardiomyopathy or broken heart syndrome.(Happy Valentine’s Day! Stay safe out there.) #EMS #EMT #Paramedic #AEMT pic.twitter.com/OgRmTS1mUQ

— Limmer Education (@LimmerEducation) February 14, 2022

Octopus Hearts Frequently Asked Questions

How many hearts does an octopus have?

Three! 💙💙💙Octopuses have two branchial hearts, which pump blood through the gills to pick up oxygen, and one systemic heart, which circulates that oxygenated blood throughout the rest of the body. This unique three-heart system is a hallmark of cephalopod physiology!

How Many Chambers Does an Octopus Heart Have?

Each of an octopus’s three hearts has a single chamber, unlike the human heart, which has four chambers (two atria and two ventricles). This simpler structure means each octopus heart is more like a specialized pump than a multi-stage circulation engine. The trade-off? They need three of them to get the job done.In humans, our four-chambered heart handles the entire circulatory loop: receiving deoxygenated blood, pumping it to the lungs, receiving oxygenated blood, and pumping it out to the body. All in one organ.Octopuses split that workload. Each branchial heart is a single-chambered pump dedicated to pushing blood through one gill. The systemic heart is also single-chambered, but it handles all the body-wide circulation. Think of it like having three specialized pumps instead of one multi-tasker.Why the simpler design? Single-chambered hearts are common in mollusks and work great when you have multiple hearts to share the load. The octopus system is less about complexity and more about teamwork: two hearts handle oxygen pickup, one handles delivery, and together they keep that thick blue blood moving.

Do all three octopus hearts beat at the same time?

Not always!The systemic heart actually stops beating when the octopus swims. It’s thought to be a way to conserve energy during intense movement. This is one reason octopuses prefer crawling over swimming!

Can an octopus survive if one heart stops working?

No. 😔 💔💙💔Each of the three hearts has a specialized role. The systemic heart maintains circulation to the body, while the branchial hearts handle oxygen uptake at the gills. There is no evidence of functional redundancy (they don’t back each other up)—meaning damage to one heart would seriously compromise oxygen transport and survival. Octopus Hearts = vital and non-redundant. No branchial heart? No oxygen pickup.No systemic heart? Oxygen can’t travel to the body.That’s why an octopus can’t survive the loss of a heart…lose one, and the whole circulatory system goes down!

Do all octopus species have three hearts?

Yes!Every known octopus species—from deep-sea octopods to tropical reef octopuses—All have the same three-heart setup. It’s a defining feature of their circulatory system.

What happens to an octopus’s hearts when it sleeps? 🐙💤

They keep beating, but slow down.When an octopus sleeps, its systemic and branchial hearts continue beating, but at a reduced rate, conserving energy. During quiet sleep, the heartbeat is steady and slow. But during active sleep, a phase scientists think may be similar to REM sleep in humans, the octopus’s skin changes color, its arms twitch, and its heartbeat becomes irregular.This has led researchers to suggest that octopuses may be dreaming. If true, they’d be one of the few invertebrates known to have such vivid sleep cycles. And yes, while all that dreaming is going on, their three hearts are still quietly working behind the scenes.

Why is octopus blood blue, but not their hearts?

The blue color comes from hemocyanin in the blood, not the muscle tissue of the heart. The hearts themselves are pinkish or greyish-white, not sapphire gems like you’d hope. 💎

Why does an octopus’s heart stop when it swims?

Because jet propulsion puts the squeeze on circulation! Here’s what’s happening under the octo hood:When an octopus wants to swim, it draws water into its mantle cavity (inhales), that’s the big bag lookin’ thing behind its eyes. Then, it forcefully contracts (exhales) its mantle muscles to push that water out through a funnel (called the siphon), rocketing the octopus backward. This is called jet propulsion.But here’s why one heart stops: that powerful squeeze also compresses the veins returning blood to the systemic heart (the one that pumps oxygenated blood through the body). With reduced venous return, the heart doesn’t have enough incoming blood to pump out, so it temporarily stops beating! For our visual minded folks, picture an octopus’s mantle cavity like a water balloon being filled through a thin straw. The straw represents the veins bringing blood back to the heart.Now, squeeze that balloon hard. What happens? The straw collapses. No more water can enter.That’s what happens when an octopus swims: the mantle contracts to force water out (jet propulsion), but the pressure is so strong it compresses the veins that feed the systemic heart. With no incoming blood, the heart pauses until the pressure eases.This is why benthic octopuses, like Octopus vulgaris, prefer crawling. Walking doesn’t interfere with circulation, so all three hearts keep working. Swimming is fast but costly, like sprinting while holding your breath!

If you want to educate yourself some more about all sorts of different cephalopods, take a look at our encyclopedia. Or, what we call it, our Octopedia!

Connect with other octopus lovers via the OctoNation Facebook group, OctopusFanClub.com! Make sure to follow us on Facebook and Instagram to keep up to date with the conservation, education, and ongoing research of cephalopods.

More Posts To Read:

• Remarkably Bright Creatures Netflix Movie: Release Date, Cast, and How “That Octopus Book” Took Over
• Octopus Intelligence: How Do You Measure the IQ of an Octopus?
• Blue Lined Octopus Mating Explained: Why Males Inject Venom During Sex
• Octopus Expert Reacts to Viral Octopus Riding a Shark (and More)
• Octopuses Punch Fish That Cheat During Hunts, New Study

Warren K Carlyle IV

Warren Carlyle is an internationally recognized octopus expert and founder of OctoNation, the world’s largest octopus fan club and nonprofit organization dedicated to octopus education.

Dubbed the “OctoKing” by Sy Montgomery and featured as a co-author on National Geographic’s SecretsOfTheOctopus.com, Warren has spent over a decade making octopus science accessible and entertaining for all ages. As the Octopus’ PR agent, Warren regularly collaborates with hundreds of underwater photographers, marine scientists, artists, and aquarists to create engaging, research-backed content that reaches millions monthly. As Jacques Cousteau said, “People protect what they love.”OctoNation’s community of over 1 million members couldn’t agree more. 🐙Want to get involved? Email Warren at [email protected]