Jellyfish Show Amazing Cognitive Abilities with Neurobiologist Anders Garm's Research

Friday - September 22 2023, 16:19 UTC - 1 year ago

A study from the University of Copenhagen conducted by Professor Anders Garm and Jan Bielecki from Kiel University discovered that Caribbean box jellyfish can learn from their mistakes, with the ability to modify their behaviour and assess distances using contrast. The results of the study have huge implications for our understanding of our own brains and the much underestimated learning ability of jellyfish.

Jellyfish are more advanced than once thought. A new study from the University of Copenhagen has demonstrated that Caribbean box jellyfish can learn at a much more complex level than ever imagined – despite only having one thousand nerve cells and no centralized brain. The finding changes our fundamental understanding of the brain and could enlighten us about our own mysterious brains.

After more than 500 million years on Earth, the immense evolutionary success of jellyfish is undeniable. Still, we’ve always thought of them as simple creatures with very limited learning abilities.

The prevailing opinion is that more advanced nervous systems equate with more advanced learning potential in animals. Jellyfish and their relatives, collectively known as cnidarians, are considered to be the earliest living animals to develop nervous systems and to have fairly simple nervous systems and no centralized brain.

For more than a decade, neurobiologist Anders Garm has been researching box jellyfish, a group of jellyfish commonly known for being among the world’s most poisonous creatures. But these lethal jellies are interesting for another reason as well: it turns out that they are not quite as simple as once believed. And this shakes our entire understanding of what simple nervous systems are capable of.

"It was once presumed that jellyfish can only manage the simplest forms of learning, including habituation – i.e., the ability to get used to a certain stimulation, such as a constant sound or constant touch. Now, we see that jellyfish have a much more refined ability to learn, and that they can actually learn from their mistakes. And in doing so, modify their behavior," says Anders Garm, an associate professor at the University of Copenhagen’s Department of Biology.

One of the most advanced attributes of a nervous system is the ability to change behavior as a result of experience – to remember and learn. The research team, headed by Jan Bielecki of Kiel University and Anders Garm, set out to test this ability in box jellyfish. The findings have just been published in the journal Current Biology.

The scientists studied the Caribbean box jellyfish, Tripedalia cystophora, a fingernail-sized medusa that lives in Caribbean mangrove swamps. Here, they use their impressive visual system including 24 eyes to hunt for tiny copepods among mangrove roots. While making for a good hunting grounds, the web of roots is also a dangerous place for soft-bodied jellies.

So, as the small box jellyfish approach the mangrove roots, they turn and swim away. Should they veer too soon, they won’t have enough time to catch any copepods. But if they turn too late, they risk bumping into the root and damaging their gelatinous bodies. Thus, assessing distances is crucial for them. And here, contrast is the key, as the researchers discovered: .

"Our experiments show that contrast, i.e., how dark the root is in relation to the water, is used by the jellyfish to assess distances to roots, which allows them to swim away at just the right moment. Even more interesting is that the relationship between distance and contrast changes on a daily basis, and that the jellyfish remember this," says Jan Bielecki.

This study shows just how amazing jellyfish can be and how much more complexity they may be capable of. As we continue to unravel these mysteries, it may help us understand the evolution of our own brains.