A leech (Hirudinea) has 32 brains throughout its segmented body. An Octopus (Octopoda) has 9 brains, one for its head and 8 for its arms (legs?).
How do these animals process tasks using multiple brains? It would suck if 3 out of your 8 arms wanted to go find a place to hide while your brain and other 5 arms are actively hunting.
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You don’t really get to have a single answer for all multi brained creatures.
You see in many ways, octopuses are the closest thing to having aliens on earth. These intriguing cephalopods are incredibly unique, boasting three hearts pumping blue blood. Octopuses possess a central brain. Situated between their eyes, this brain has a distinct doughnut-like shape, forming a ring around the creature’s esophagus. Technically, when an octopus ingests food, it passes through the “center” of this central brain. This is just one of many facts highlighting how different the anatomy of an octopus’s nervous system is compared to vertebrates and many other invertebrates. Neurons are like messengers that send signals and information from the brain to various parts of a creature’s body. Across its entire body, the typical octopus – scientific name Octopus vulgaris – possesses approximately 500 million neurons. That may sound like a lot, but humans have upwards of 100 billion. However, octopuses have roughly the same number of neurons as dogs, known for their ability to learn various commands. Therefore, it’s not much of a stretch to say that octopuses are keenly intelligent – especially for invertebrates.
Approximately 180 million of the 500 million neurons found in an octopus are concentrated in the central brain. Roughly 40 million or so additional neurons are located in each of the ganglia of each of its eight arms, or tentacles. Therefore, 320 million of an octopus’s neurons – more than two-thirds of them – are found at the bases of its arms rather than in its central brain. Incredibly, a single octopus arm possesses more neurons than you will find in a frog’s entire body – just one of many intriguing facts about their nervous systems. Because each arm has its own ganglia, or cluster of neurons, each arm can act independently of an octopus’s central brain and other arms. The neurons at the base of each arm connect to suckers spread across it; typically, each arm has roughly 250 suckers. Each sucker may have around 10,000 neurons, which it uses to detect physical sensations via touch. These neurons also sense chemicals, allowing each arm to smell and taste objects while exploring them. Octopuses lack proprioception. This means that they don’t have a fixed “map” in their minds allowing them to know what various parts of their bodies are doing. While a human can target a spot on their back without physically seeing it, octopuses lack this perception entirely. There’s a good reason for this: Unlike humans, octopuses don’t maintain a static body shape. Instead, their bodies are remarkably fluid, constantly changing to adapt to the environment. Octopuses make up for their lack of proprioception by having those separate “mini-brains” at the base of each of their eight arms.
Oh, and here are cons to having multiple brains for octopus.
They can react faster to threats because individual ganglia don’t have to communicate with the central brain.
They can fine-tune the movement of each arm, passing the work off to the ganglia.
They can regenerate new arms if one is severed – and the new arm even generates a new ganglion.
As for your leech creatures, not exactly, but you can say that. Leech is an annelid, which are catagorized by body segmenta. But unlike other annelids, it’s internal and external segmentation do not correspond each other. Internally it’ body is divided into 32 parts each with its own corresponding brain! They are not actually different but its just the same brain that is segmented. Each segment has its own neuronal ganglia which are connected to the adjacent one. So precisely it does not have 32 brains but a single brain that exists in 32 parts throughout the body (Anatomically). But physiologically because each ganglia control their respective segments,and usually work independently, you can also say that it have 32 brains! (Physiologically).
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