The octopus's brain may not seem big compared to yours, but as far as his fellow invertebrates are concerned, it's huge. Octopi are smart creatures, particularly compared to other invertebrates, and observation reveals that they exhibit human traits like problem-solving, self-entertainment and tool use. Not only does the octopus have a brain, then, but he really knows how to use it.
Octopus Brain Structure
While your brain resides in your head, other animals, like snails, have brains that are spread throughout their bodies. Ganglias, or nerve cell clusters, are distributed through the body in small groups. In the octopus, however, most of their ganglias bunch together, creating a brain structure. While it's a different type of brain than ours, it's a brain nonetheless, and it makes him the most intelligent invertebrate on the planet. Like the snail, he also has ganglia elsewhere in his body -- he has smaller brain-like structures in each of his arms.
Tools and Problems
Octopi demonstrate their intelligence all the time, allowing scientists to observe and confirm that they're smart creatures. For example, an octopus may carry two halves of a coconut in his tentacles in case he encounters a predator -- when he sees one, he can hide himself inside, closing the two halves around his body. He's also a problem-solver -- if he can't open a clamshell using one method, for example, he'll experiment with other methods until he finds one that works. His capacity for lateral thinking and tool use is a marker of brain power and even curiosity.
The octopus brain has an impressive capacity for learning, and he uses that combination of curiosity and memory to entertain himself. Under observation, octopi that are given floating toys use them to entertain themselves -- for example, he may shoot a water jet at the object and launch it into a water current that brings it back. Like bouncing a tennis ball against a wall, it's his way of playing when he's by himself, which isn't typical of invertebrates.
These creatures are largely products of their environment -- more specifically, the coral reef. With a wide variety of predators, prey and plant life, the coral reef is a highly complex environment. Navigating and surviving this environment has forced the octopus to evolve into a highly intelligent, adaptable animal. For example, octopi are able to explore and mentally map out the environment around them, using landmarks and memory to remember the complex layout of an area and navigate without retracing their steps.
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Tom Ryan is a freelance writer, editor and English tutor. He graduated from the University of Pittsburgh with a degree in English writing, and has also worked as an arts and entertainment reporter with "The Pitt News" and a public relations and advertising copywriter with the Carnegie Library of Pittsburgh.