With eight tentacles, a massive brain, and a surprisingly malleable body composition, octopuses are among the weirdest and most intriguing creatures around.

Living at depths of anything from around 700 to 7000 meters below the surface of our oceans, these captivating marine animals have beguiled and enchanted researchers and animal lovers alike for generations.

And a new paper published in the Bulletin of Marine Science recently has only added to the mystifying nature of these incredible cephalopods.

In fact, the researchers from Field Museum in Chicago have discovered something so intriguing about one species of octopus, that it could change how we think about the creatures forever.

Up to 9,000 feet below the surface of the Pacific Ocean, lives a group of curious and elusive octopuses known as Graneledone pacifica, or the Pacific warty octopus.

If their name wasn’t enough to give it away, one of the most characteristic things about these creatures is the warts that cover their skin.

But these types of octopus have been at the centre of debate for some time now, since there is a huge level of variability in the number and size of their warts.

As a result, as the Field Museum’s associate curator of zoology, Janet Voight, explained in a statement, scientists were none the wiser as to whether these octopuses belonged to the same species or different ones. And, if they were of the same species, why there was so much variability in their warts:

“If I had only two of these animals that looked very different, I would say, ‘Well, they’re different species, for sure.’ But variation inside animal species can sometimes fool you. That’s why we need to look at multiple specimens of species to see, does that first reaction based on two specimens make sense?”

With this goal in mind, the team took a deep-dive into the warty octopus – and were staggered by what they found.

To truly understand the octopuses, the researchers collected fifty of the creatures from different depths of the Northeast Pacific.

In order to obtain a representative sample, individuals from as far apart as Washington State and Monterey, California, were examined, with the creatures obtained from between 3,660 feet and 9,000 feet below the surface of the ocean.

To classify the octopuses, and truly understand if they were of the same or different species, the researchers counted how many warts were on the back and head of each individual, as well as how many suckers were on their arms. They then obtained DNA samples, to underpin their observations.

And the incredible truth is that all of the warty octopuses – despite huge variation in their warty appearance – were of the same species, with DNA sequencing confirming this.

So why do these individuals look so different to one another?

Well, the research team explain, that seems to depend on where exactly they were collected – and not the geographical location, but the depth of the waters they live in.

The deeper these octopuses live in the ocean, they concluded, the wartier they were – and, incidentally, the smaller they were too.

And though they have no answers yet as to the wartiness, the size makes total sense, as Voight explained:

“There’s less food as you get deeper in the ocean. So these animals have to work harder to find food to eat. And that means at the end of their lives, they’ll be smaller than animals who have more food. If you’re a female who’s going to lay eggs at the end of your life, maybe your eggs will be smaller.”

As a result of this, the hatchling octopuses would be smaller too, ultimately corresponding with smaller individuals who have developed that way in order to survive in an ecosystem where food is few and far between.

Though this gives the researchers a vital understanding of the differences between this one species, it also gives a deep insight into how the octopuses can – and have – adapted accordingly with their surroundings, a potentially crucial piece of knowledge as we face the growing challenges of the climate crisis.

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