“Octopuses have nine brains”

Octopuses possess a truly fascinating and unique neurological architecture, which often leads to common misunderstandings about their brain count. While the idea of a creature with multiple brains might sound like science fiction, the way an octopus's nervous system is distributed gives rise to the plausible notion that they have more than one. This misconception largely stems from observing the remarkable independence and coordination of their eight arms.

Scientifically, an octopus has one primary, centralized brain located in its head, which is responsible for complex cognitive functions such as learning, memory, and decision-making. However, each of its eight arms also contains a significant cluster of nerve cells known as a ganglion, situated at the base of the arm. These eight ganglia function as subordinate "mini-brains," allowing each arm to operate with a high degree of autonomy. For instance, an arm can taste, touch, and even manipulate objects independently, often without direct instruction from the central brain for every single movement. A staggering two-thirds of an octopus's total neurons are found within these arms, underscoring their remarkable processing power.

The belief that octopuses have nine brains is therefore understandable, given the highly decentralized nature of their nervous system. When an octopus arm can independently perform complex actions, such as navigating a small maze or opening a jar, it's easy to infer that each arm must possess its own brain. While these ganglia are not full brains in the same sense as the cephalic brain, their sophisticated capabilities blur the traditional definition, making the "nine brains" claim seem quite plausible to many observers of these incredibly intelligent marine creatures.