Why an octopus has three hearts and blue blood
Copper instead of iron, and two hearts just for the gills. This explainer connects the blood chemistry to the cold, low-oxygen water an octopus lives in.
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Transcript
OCTOPUS LIVES DEEP
The octopus lives on the ocean floor, in cold, deep water.
It hunts at night, crawling through rocky crevices.
Its body needs oxygen to move and think.
But deep water holds less dissolved oxygen than the surface.
The octopus solved this problem over millions of years.
THE THREE HEARTS
The octopus has three hearts, not one.
Two hearts pump blood through the gills.
One central heart pumps blood to the body.
The dual design extracts every drop of oxygen.
More oxygen reaches every tissue.
COPPER IN THE BLOOD
Octopus blood uses copper to carry oxygen, not iron.
Humans and most animals use iron-based hemoglobin.
The octopus uses copper-based hemocyanin.
Hemocyanin holds oxygen more tightly in cold water.
This works better in the deep, where it is freezing.
IRON VS COPPER
Iron hemoglobin works best in warm, oxygen-rich blood.
It releases oxygen easily at body temperature.
Copper hemocyanin grips oxygen harder.
It keeps oxygen bound even in frigid deep water.
Two adaptations: one system for each world.
WHY THE BLOOD TURNS BLUE
Copper changes colour when it binds oxygen.
Without oxygen, hemocyanin looks clear and colourless.
With oxygen bound, it turns bright blue.
The blood cycles between clear and blue with each breath.
This blue colour is the mark of a deep-sea hunter.
THE FULL CIRCLE
The octopus gills extract oxygen from the water.
The two gill hearts boost the blood through.
Hemocyanin carries the oxygen to every arm.
The central body heart keeps the flow steady.
All three hearts work together to survive the deep.
DEEP-SEA ENGINEERING
The three hearts and blue blood are not luck.
They are the octopus's answer to the deep.
Every part works together to solve one problem.
How to hunt and live where oxygen is scarce.
Evolution built the perfect system for that world.
Every sentence above was written before a single picture was drawn, then each object it names was painted for this video alone.
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