Jellyfish brain

Or at least, there is no brain as we usually understand it. They move thanks to a network of nerve cells distributed throughout the body, but without central “gray matter”.

However, this did not prevent 12 representatives of a species called the box jellyfish or Caribbean jellyfish (Tripidalia cestophora), to learn how to avoid the trap. in research Published on September 22 Current biologyResearchers from Denmark and Germany describe an experiment conducted in an aquarium, where they painted the walls to mimic the environment of plant roots (called mangroves) that these animals are familiar with, but with an optical illusion that made the roots appear even further away. They actually were. First, the jellyfish hit the walls; After a few minutes, they learned to avoid it.

The researchers point out that these jellyfish have four visual organs distributed around their body, and each of them has six sensors. For a total of, so to speak, 24 “eyes.” In the past, biologists have tried to understand the workings of this “brainless nervous system.” supposed These visual organs replaced the brain by sending the necessary information to the rest of the body to avoid obstacles, which is information that the jellyfish certainly needs, in an environment where the roots, near the shores, form obstacles that vary from one place to another.

Jellyfish are not alone in the animal world: hydras, snails and starfish, among others, do not have brains either. Understanding how they work may help us understand how our neurons evolved since these species and our ancestors diverged hundreds of millions of years ago. Humans may be very different from jellyfish, but they can also be just that In the same way that, in neurons, Learning’ encoded », as well as emotion or memory.