3 hearts and blue blood: The strange survival secret of the octopus

(Dan Tri) - Octopuses have long been a subject of fascination for researchers. Not only do they have 3 hearts, blue blood and 8 independent tentacles, the octopus' brain is also extremely developed.

Not only does the octopus stand out with its eight soft tentacles and superb camouflage ability, it also amazes scientists with its complex circulatory system: three hearts working at the same time and copper-rich blue blood.

This is a miraculous adaptation to the cold, oxygen-poor oceans.

3 Hearts: Survival Solution in the Ocean

While most animals have only one heart, the octopus has three. According to biologist Kirt Onthank from Walla Walla University (USA), these three hearts are divided into two groups with different tasks.

Octopuses have a special body structure (Photo: Getty).

The largest heart – called the systemic heart – is responsible for pumping oxygen-rich blood throughout the body.

Two smaller gill hearts, directly connected to each gill, pump oxygen-poor blood through the respiratory system for gas exchange. This separation of functions allows the octopus to optimize blood circulation in the low-pressure, low-temperature conditions of the seafloor.

“These three hearts perform the same function as a four-chambered heart in humans. They create separate pressures to efficiently circulate blood to vital organs,” Onthank explained to Live Science .

A 1962 study on the giant Pacific octopus ( Enteroctopus dofleini ) revealed another strange phenomenon: the octopus' heart can stop beating temporarily when resting or swimming.

Specifically, while moving by expelling water from its body – similar to the mechanism of pushing air in a balloon – the high pressure causes the circulatory system to temporarily stop working to protect the heart from damage. Therefore, octopuses often crawl more than swim.

Blue Blood: Special Adaptive Color

Not only is the cardiovascular system unique, the blood of the octopus also has a distinctive blue color that is completely different from the red blood of humans. The cause comes from hemocyanin, a protein containing copper, instead of hemoglobin containing iron like in mammals.

According to research published in Frontiers in Zoology , hemocyanin functions more effectively in low-oxygen and low-temperature environments, which are suitable for living on the ocean floor.

Not only that, this molecule is also highly cooperative. When a hemocyanin molecule has attached to an oxygen molecule, the ability to attach other oxygen molecules will increase, improving the efficiency of gas transport.

“In short, in deep-sea conditions, hemocyanin is not inferior to hemoglobin, and is even superior in terms of survival,” Onthank said.

However, this mechanism also makes it difficult for octopuses to adapt to the terrestrial environment. Hemocyanin is easily destabilized when temperature and oxygen levels change, limiting its ability to adapt in the ocean.

Lessons for artificial intelligence and medicine

Octopuses have long been a subject of fascination for researchers. Not only do they have three hearts, blue blood, and eight independent tentacles, but their brains are also incredibly developed, with two-thirds of their neurons located in their tentacles, allowing them to make decisions on each limb without the need for a central brain to control them.

Nature magazine once called the octopus an “alien of the ocean” not only because of its unusual shape, but also because its biological structure has almost nothing in common with vertebrates.

The octopus's triple-heart circulatory structure has inspired much research in the fields of medicine and bioengineering.

According to the journal Biomechanics and Modeling in Mechanobiology, the mechanism of dividing blood flow into multiple branches and using separate "pumps" to increase pressure is an optimal model for the design of artificial hearts or biological pumping systems in robots.

Not only that, the properties of hemocyanin are also considered by scientists as a suggestion for the development of artificial oxygen carriers, especially in heart surgery or oxygen-deficient environments such as space.

Source: https://dantri.com.vn/khoa-hoc/3-trai-tim-va-mau-xanh-bi-quyet-sinh-ton-ky-la-cua-bach-tuoc-20250903071654265.htm