Octopuses are perhaps some of the ocean’s most alien creatures. Just some of their unfamiliar features include color-changing skin, three hearts that pump copper-based blood, and neurons in their arms.
That these traits are so different from our own physiology is not surprising, however, when considering that the evolutionary paths of octopuses and humans split half a billion years ago—we are more closely related to dinosaurs than we are to them.
And yet, it seems that octopuses can demonstrate what we would reasonably consider intelligence. Tool use has been observed both in wild octopuses and in captive octopuses in scientific studies. For instance, wild veined octopuses (Amphioctopus marginatus) are seen carrying around coconut shell halves, which act as shelter they can bring anywhere. Meanwhile, octopuses in captivity have been taught to solve puzzles like navigating mazes and opening screwed-on lids.
What’s more, octopuses have been seen engaged in play-like behavior—something previously documented only in mammals and birds. When researchers at the Seattle Aquarium placed octopuses in an empty tank with nothing but a pill bottle, they found that the octopuses would repeatedly blow water at the bottle, pushing it towards a water jet in the tank that would return the bottle to them. The behavior was just like how humans might bounce a ball.
So why might octopuses have evolved such capable brains? Some have hypothesized that being involved in social interactions and “cultural” exchanges like learning to use tools promote intelligence. However, octopuses are largely solitary creatures, spending most of their lives alone. As such, they don’t frequently socialize with others.
Instead, octopuses may have developed their cognition to better adapt to their complex coral reef habitats.
While animals like shrimp, crabs, or turtles have natural “armor” as defense mechanisms, the ancestors of octopuses lost their shells about 275 million years ago. Without the physical protection of a shell, intelligence became all the more important to avoid predation.
But being unrestricted by a shell is also beneficial. Octopuses could be literally more flexible in their hunting techniques. With their arms, they could reach into crevices and find many kinds of new prey. It is likely that they further developed their intelligence in order to take advantage of this new ability.
Scientific study into octopus intelligence is ongoing. But from what we already know, it’s clear that they have developed their own form of thinking despite their physiological differences from other animals traditionally considered intelligent.