How smart is an octopus?

Octopuses are often praised for their intelligence. And now researchers have also revealed the unique brainpower of different species, teaching us more about how they got so smart.

Octopuses are remarkable animals. Not just physically – did you know they have three hearts? – but also in terms of intelligence. They are masters of camouflage, capable of solving complex tasks, and their cognitive ability is said to approach that of some small mammals. But how do different octopus species actually relate to each other? And… how did they actually become so smart?

smart animals

When you think of some smart animals, you probably think of a primate, a dog, or an elephant. But octopuses prove that intelligence is not the exclusive domain of mammals. Several studies have shown that these animals have advanced cognitive skills. “They manage to escape from a water tank; a real nightmare for most octopus researchers,” said researcher Wensung Chung in conversation with Scientias.nl. “In addition, they can quickly learn conditioning, in which they can associate the performance of a certain task with a reward. In addition, octopuses have been shown to be able to return to the same den where they started after a long foraging trip. This suggests they probably have the ability to recognize and remember landmarks.”

A species

How could an octopus – an invertebrate and not really social animal – become so smart? Scientists actually know surprisingly little about it. That’s because much of the research on octopus neuroanatomy to date has focused on a single species: the European eight arm. (Octopus vulgaris). “Before our study, our knowledge of octopus brains, lobes, and underlying neural circuitry was largely based on this species,” Chung said. But what about the neural wiring of different octopus species?

In the new study the researchers decided to study the brains of different types of octopuses. Using MRI scans, they produced detailed 3D images and then compared their unique brain structures. “We examined four species, including a deep-sea octopus, a nocturnal solitary species, and two different daytime reef dwellers,” Chung said. It leads to an interesting discovery. Because according to Chung, octopus brains vary considerably, depending on where exactly a species lives, when it is active and whether it ever comes into contact with other animals.

The octopus brain

The results show that the deep-sea octopus has a fairly flattened brain, similar to that of marsupials and rodents. This brain fits well with its slow pace of life and limited interactions with other animals. In contrast, reef octopuses have significantly larger brains. This means that these species have more cognitive skills and can, for example, perform more complex visual tasks or engage in social interactions. “These octopuses exhibit remarkably complex behaviors that are not known in other cephalopods,” Chung said.

Joint hunt

For example, reef octopuses and fish are known to sometimes hunt together, meaning that these very different species are able to understand each other. And that’s pretty special. “Unlike fish, reef octopuses have a fairly short life and die after about a year,” Chung explains. “So while fish learn how to best interact with an octopus over their longer lifespan, an octopus needs to learn this successful joint hunt in a much faster way. Octopuses, however, are able to very quickly recognize fishy gestures (for example, standing posture and color patterns) that indicate a tasty snack hiding in a crevice. This is truly a remarkable learning ability, showing that some octopus species have complex cognitive abilities. They must first see the signal, interpret it and then react to it. It’s really great!”

In this study, see how a reef octopus and a fish hunt together.

Evolution

Overall, the findings indicate that the smartest octopuses are in habitats where they also desperately need that intelligence. “Octopuses are found in many different parts of the ocean; from the reef, to the deep sea and from tropical to temperate waters,” Chung explains. “Here they are exposed to various predators, which they have to anticipate.” It means that octopus intelligence probably arose from a dire need to react to their environment. And that is strikingly similar to the development of intelligence in vertebrates. “Our study confirms that the octopus brain structure evolved in the same way as many other animals,” Chung concluded. “For example, it’s similar to the evolution of sharks, which also live at many different depths in the ocean.”

What this study teaches us? “In particular, octopuses – but also other cephalopods – are probably a lot more complicated and more difficult to understand than we previously expected,” Chung said. “But extending the study of octopuses to different species that live in different habitats — rather than limiting ourselves to just one model species — is a good way to study these amazing and seemingly smart creatures, I think. In addition, I believe we can learn a lot more by embracing the diversity of these animals. So this research is just the beginning.”