Why Does an Octopus Have Three Hearts?

Did you know: an octopus has 3 hearts? 

Is it because if one breaks, he still has 2 more?

Or maybe something like 2 backup lives?

Unfortunately for Mr. Octopus there, no.

Okay, so starting with the basics. An octopus is a 'cephalopod' (it comes from the Greek words kephalē - meaning "head" - and pous - meaning "foot". It translates to head-footed, which basically means having tentacles or feet attached to the head). So cephalopods have closed circulatory systems where blood flows within vessels and does not bathe the tissues.

THREE HEARTS

They have 3 hearts each with different functions. There are 2 Branchial hearts which are small and are located near the gills. They pump deoxygenated blood to the gills, where they get oxygenated. They also have 1 Systemic heart which is larger and pumps oxygenated blood from the gills to the rest of the body, powering the octopus's organs and muscles. 

AND THE HEART STOPPED

When an octopus swims, the Systemic heart stops beating as if saying, "Yep, now's time for that nap I've always been talking about.". Whoaaa, how does this occur? Well, when it swims, it uses a method called 'jet propulsion' where it shoots water out to move, which creates a pressure in its body making it harder for the gills to get enough oxygen from the water. This causes the systemic heart to save energy, because it doesn't want to waste energy moving blood that has barely any oxygen. 

That's why octopuses are usually seen lazily crawling around the floor, because that requires lesser energy than swimming. 

With the systemic heart inactive, the octopus can't supply its muscles with as much oxygen as it can while resting or crawling. Hence, there is lesser aerobic respiration, causing lesser energy production. This causes them to tire quickly. Hence, they usually swim only when they need to escape predators, because the survival instinct of saving their life overrides that to save energy. 

COPPERY BLOOD

Humans have iron-based Haemoglobin, but octopuses beg to differ. They have a copper-based blood called Hemocyanin that transports oxygen. It is more efficient than Haemoglobin in cold, low oxygen environments which is why Octopuses can live in deep, cold waters and pull it off with a simple wave of a tentacle.

We've all heard that royalty are blue-blooded, but these Octopuses are actually blue-blooded, because this copper gives their blood a blue hue. 

AMAZING ADAPTATIONS

An octopus has some crazy adaptations like camouflage, color-changing, highly developed intelligence, blue blood, three hearts, jet propulsion, regeneration of arms, advanced senses and the good ol' ink defense.

So the next time you're struggling with daily happenings, well, the octopus can make do with one less heart! That is seriously saying something.