Brainless Brilliance: Jellyfish have an incredible capacity for learning
Although they do not have a centralized brain, Jellyfish can learn from past experiences, just like humans, mice and flies. Scientists studied it Caribbean jellyfish (Tripedalia cystophora) to notice and avoid obstacles.
This study challenges previous notions that advanced learning requires a centralized brain and sheds light on the evolutionary roots of learning and memory, writes "SciTech Daily" (SciTech Daily).
No bigger than a fingernail, these seemingly simple jellyfish have a complex visual system with 24 eyes embedded in their bell-like bodies. Living in swamps, this animal uses its vision to move through murky waters and around underwater roots to catch prey.
Scientists have proven that jellyfish can acquire the ability to avoid obstacles through associative learning, a process by which organisms form mental connections between sensory stimuli and actions.
Learning is the pinnacle of the nervous system's role. To teach a jellyfish a new trick, it's best to use its natural actions, something that makes sense to it, to reach its full potential.
In an attempt to simulate the jellyfish's natural environment, the researchers decorated a circular aquarium with gray and white stripes that mimic distant roots. They observed the jellyfish in the aquarium for 7,5 minutes. At first she swam close to those seemingly distant lanes and often bumped into them.
However, by the end of the experiment, the jellyfish had increased its average distance from the wall by about 50 percent, quadrupled the number of successful turns to avoid collisions, and cut its contact with the wall by half. The findings suggest that jellyfish can learn from experience through visual and mechanical stimuli.
"If you want to understand complex structures, it's always good to start as simple as possible," says Anders Garm of the University of Copenhagen in Denmark.
"By looking at these relatively simple nervous systems in jellyfish, we have a much better chance of understanding all the details and how they come together to perform a procedure."
The scientists then tried to identify the process underlying the jellyfish's associative learning by isolating the visual sensory centers. Each of these structures contains six eyes and creates pacemaker signals that control the jellyfish's pulsating movement, the frequency of which jumps when it moves away from obstacles.
The findings further indicated that a combination of visual and mechanical stimuli is required for associative learning in jellyfish and that visual sensory centers serve as a learning center.
The research team plans to better study the cellular interactions of the jellyfish's nervous system to dissect memory formation. They also plan to further study how the mechanical sensor in the bell works to get a complete picture of this animal's associative learning.
“It's surprising how quickly these animals learn; roughly the same speed as advanced animals," says Garm. "Even the simplest nervous system appears to be capable of advanced learning, and this may turn out to be a very basic cellular mechanism created early in the evolution of the nervous system."