Octopuses are invertebrate animals, but the absence of a central nervous system like that of birds or mammals does not make their brains less interesting than the rest. Brains, emphasizing the plural since neuronal systems of each of its extremities They have a degree of independence, which leads many to consider them as such.
A nervous system not at all central. In January 2025, a group of researchers has studied the nervous systems of these cephalopods to better understand how these nine neural organs operate together and to what extent they maintain their independence. What they observed is that each of these brains had the ability to operate individually.
The team responsible for the study believes that it is thanks to the unique segmentation of the nervous system of octopuses that these animals achieve the level of skill in the management of extremely flexible organs that serve these animals to move, feed, sense their environment, and even copulate.
“If you are going to have a nervous system that is going to control such dynamic movement, that is a good way to organize it,” explained in a press release Clifton Ragsdale, co-author of the study. “We think it’s a feature that evolved specifically in soft-bodied cephalopods with suction cups to carry out these worm-like movements.”
Studying segmentation. The study focused on segmentation of this curious neuronal system, analyzing the distribution and function of the neurons in these arms, taking as reference an octopus of the species Octopus bimaculatus. Neurons that together add up to a greater number than the neurons located in the “central brain” of the animal, which is responsible for coordinating actions that require the use of various arms.
These neurons in the extremities are concentrated, explains the teaminto an axial nerve chord (ANC), which “snakes” the limb to each of the animal’s suction cups.
Neural columns. The ANC analysis showed that neurons in the octopus’s limbs were grouped into “columns” that in turn formed segments that the team compared to corrugated pipes. The segments were in turn separated by gaps called “septa” from which nerves and blood vessels made their way to the muscles of the limb.
“From a modeling perspective, the best way to organize a control system for this long and flexible arm would be to divide it into segments,” Cassady Olson added.co-author of the study. “There must be some kind of communication between the segments, which you can imagine attenuates their movements.”
Job details can be found in an article published in the magazine Nature Communications.
Much to investigate. In fact, a subsequent joint study between Florida Atlantic University and the Marine Biological Laboratory analyzed 4,000 arm movements, captured on video, from three different species and came to a surprising conclusion: although all arms can perform any movement, according to his research, the front arms are used for exploration, while the rear arms are used for everything that has to do with movement.
The arms of octopuses are very versatile limbs that allow this animal to navigate the seabed, but also, through their suction cups, allow these octopods to perceive the world around them, hunt and feed on their prey. Knowing the details of the functioning of such complex limbs will still require new research.
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Image | Theasereje, CC BY-SA 4.0
This article was originally published in 2025, but we have updated it with new information
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