First, it is important to state that octopuses are marine creatures. Their entire life cycle takes place in the water. At no time should you ever take an octopus out of the water on purpose.
With that said, octopuses can survive outside of water for a few minutes. In order to understand how this is so, it is important to understand how octopuses get their oxygen.
Gills and Skin
Being aquatic, octopuses rely on gills to extract oxygen from the water. Octopuses have three hearts. Two of these organs are used to pump blood specifically to the gills in order to remain oxygenated. In case you were curious, the other heart circulates the blood to the rest of the octopus’ body.
Unlike other marine creatures, such as fish, which rely entirely on gills for oxygen transfer, an octopus has an advantage. They can also absorb oxygen from the water through their skin. This is accomplished through a process known as passive diffusion.
When an octopus is at rest, over 40 percent of its oxygen requirements can be met by this form of gas exchange between its skin and the surrounding water. When it is swimming or engaged in other activity, the oxygen absorbed through the skin drops to less than 30 percent.
The lowest that oxygen absorption through the skin gets is immediately after an octopus eats. Even if motionless, during digestion, the oxygen absorption drops to the single digits. Sometimes as low as 3 percent.
Water is Key
As you can see, the main ingredient required by an octopus to get oxygen is water.
So, what happens if an octopus is out of the water? Well, first the gills become ineffective. This because they cannot draw oxygen from the air and also because without water the lack of buoyancy causes them to collapse. If the lack of water is for a brief period, the gills normally regain their buoyancy and oxygen absorption ability once the octopus is back in the water.
The only source of oxygen for an octopus on land would be the residual moisture from the water on its skin. This would not last for too long. Besides, even at peak efficiency, less than half of its oxygen requirements can ever be met through passive diffusion.
Tidal Pool Octopuses
There are some species of octopus which live near areas of coastline which have tidal pools during low tide. These octopuses purposefully come onto the areas of receded water in order to crawl from tidal pool to tidal pool to catch crabs and other creatures waiting for high tide to return in those tidal pools. These octopuses use the passive diffusion of oxygen through their skin to survive these short jaunts on land.
Even these tidal pool octopuses keep their “land time” to a minimum. It only requires them to spend less than a minute on land to get from tidal pool to tidal pool.
In short, an octopus could survive out of the water for several minutes. The longer it is out of the water, the greater the risk of it suffering damage to its gills. If outside for too long, an octopus will die.
