Organism without brain can nevertheless learn. What does this imply?

[Bernard NebelKeymaster]

We assume that all learning occurs in the brain. Yet these these tiny jelly fish, which  don’t have a brain,  nevertheless demonstrate learning.This article should generate some interesting and fun discussion.  (Would you enjoy more such articles or is it a distraction you would rather do without? Please comment.)

ANIMAL BEHAVIOR  |  NEWS FROM SCIENCE

Tiny jellies don’t need a brain to learn

The Caribbean box jelly (Tripedalia cystophora) has an astonishingly complex visual system. JAN BIELECKI

If beauty is truly in the eye of the beholder, then the Caribbean box jelly (Tripedalia cystophora) might be the world’s leading expert on aesthetics. This fingernail-sized jelly may not have a brain, but it does have a whopping 24 eyes, which help it hunt and dodge underwater roots in its mangrove habitat. Now, research published in Current Biology suggests T. cystophora can also learn from past experiences—an ability never before observed in an animal with such a simple nervous system. Since jellyfish have no centralized brain-like structure, they’re viewed as both literally and figuratively “unbrainy,” Macquarie University animal behavior expert Ken Cheng writes in an accompanying Dispatch. Still, when researchers dressed the walls of a tank with gray and white stripes, the animals quickly began associating the gray stripes with the pain of collision and started swimming away from them. That indicates that box jellies can draw connections between two types of stimuli—a phenomenon known as associative learning. Before now, scientists believed this type of learning was restricted to animals with more advanced nervous systems, like humans and other mammals. The findings suggest that learning is an integral part of the animal nervous system, the researchers say. Box jellies and their relatives are believed to have evolved over 500 million years ago, making them one of the world’s oldest animals, so it’s possible that the neural mechanisms of learning are just as ancient.

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