ZME Science
No Result
View All Result
ZME Science
No Result
View All Result
ZME Science

Home → Environment

Jellyfish can learn just like humans — even though they lack a brain

Turns out, jellyfish are not just simple, pulsating blobs—they can learn from experience.

Fermin KoopbyFermin Koop
October 2, 2023
in Animals, Biology, Environment, News
A A
Edited and reviewed by Zoe Gordon
Share on FacebookShare on TwitterSubmit to Reddit

Jellyfish are much more advanced than we thought. A new study has shown that the Caribbean box jellyfish (Tripedalia cystophora) can learn at a much more complex level, using knowledge from past experiences just like humans, mice and flies. The findings, the researchers said, could change what we know about how cognition works.

jellyfish bell
Image credits: Jan Bielecki.

While they’ve been around for over 500 million years, jellyfish are usually described as simple creatures with limited learning skills. They and their relatives, collectively known as cnidarians, are considered to be the earliest extant animals to develop nervous systems. Jellyfish have no brains, though.

Neurobiologist Anders Garm has been researching box jellyfish for over a decade, a group of jellyfish known for being among the world’s most venomous creatures. But these jellies are also interesting for another reason. It turns out they aren’t as daft as once believed, changing our understanding of what simple nervous systems can do.

“It was once presumed that jellyfish can only manage the simplest forms of learning, including habituation (the ability to get used to a certain stimulation). Now, we see that jellyfish have a much more refined ability to learn, and that they can actually learn from their mistakes,” Garm, one of the study’s authors, said in a news release.

Responding to experience

One feature of more advanced cognitive abilities is changing one’s behavior as a result of experience. In other words, to remember and learn. Garm and his team wanted to test this in box jellyfish. They focused on the Caribbean box jellyfish, a fingernail-sized medusa that lives in mangrove swamps in the Caribbean.

First, the researchers decorated a round tank with grey and white stripes to simulate the jellyfish’s natural habitat, with grey stripes mimicking mangrove roots. At first, jellyfish swam close to the stripes and bumped into them. However, by the end of the experiment (7.5 minutes later), the jellyfish increased their average distance from the wall by about 50%.

Image credits: Bieleki et al.

Jellyfish quadrupled the number of successful pivots to avoid collision and reduced their contact with the wall by half, suggesting they can learn from experience through visual stimuli.

“We can see that as each new day of hunting begins, box jellyfish learn from the current contrasts by combining visual impressions and sensations,” Garm said.

RelatedPosts

Robot jellyfish that runs on hydrogen can swim forever in the ocean
Scientists design ‘Pokéball’ that safely captures even the most delicate underwater creatures
This super rare spotted box jellyfish has only been recorded once before
The deadliest creature in the world

The researchers then wanted to identify the underlying process of the jellyfish’s associative learning by isolating the animal’s visual sensory centers, known as rhopalia. These sensory structures carry six eyes and trigger pacemaker signals that coordinate the jelly’s pulsing motion, which increases in frequency when the animal veers away from obstacles.

They isolated individual rhopalia and placed them in front of moving grey bars to mimic approaching objects. At first, the structure didn’t respond to light grey bars, interpreting them as distant. However when stimulated with a combination of visual cues and weak electric signals, these structures generated responses that helped the jellyfish avoid obstacles, proving that even with a very basic nervous system, these animals can learn through a form of ‘associative learning.’

“Despite having a mere one thousand nerve cells, they can connect temporal convergences of various impressions and learn a connection — or what we call associative learning,” Garm said.

The next steps

The study challenges previous scientific perceptions of what animals with simple nervous systems can do. For overall neuroscience, it’s really big news, Garm said. “This suggests that advanced learning may have been one of the most important evolutionary benefits of the nervous system from the very beginning,” he added.

Future research will delve into how exactly these jellyfish store memories and further explore their sensory systems.

“It’s surprising how fast these animals learn; it’s about the same pace as advanced animals are doing,” Garm said in a statement.

The study was published in the journal Current Biology.

Tags: jellyfish

ShareTweetShare
Fermin Koop

Fermin Koop

Fermin Koop is a reporter from Buenos Aires, Argentina. He holds an MSc from Reading University (UK) on Environment and Development and is specialized in environment and climate change news.

Related Posts

Animals

This Benjamin Button-like Jellyfish Can Age in Reverse, From Adult to Juvenile

byTibi Puiu
9 months ago
Artistic reconstruction of a group of Burgessomedusa phasmiformis swimming in the Cambrian sea. Image credits: Christian McCall.
Animals

Scientists identify the oldest known species of swimming jellyfish

byFermin Koop
2 years ago
Invertebrates

This super rare spotted box jellyfish has only been recorded once before

byTibi Puiu
2 years ago
Invertebrates

Giant files: Nomura and Lion’s mane jellyfish

byMihai Andrei
2 years ago

Recent news

The Worm That Outsourced Locomotion to Its (Many) Butts

May 16, 2025

The unusual world of Roman Collegia — or how to start a company in Ancient Rome

May 16, 2025
Merton College, University of Oxford. Located in Oxford, Oxfordshire, England, UK. Original public domain image from Wikimedia Commons

For over 500 years, Oxford graduates pledged to hate Henry Symeonis. So, who is he?

May 16, 2025
  • About
  • Advertise
  • Editorial Policy
  • Privacy Policy and Terms of Use
  • How we review products
  • Contact

© 2007-2025 ZME Science - Not exactly rocket science. All Rights Reserved.

No Result
View All Result
  • Science News
  • Environment
  • Health
  • Space
  • Future
  • Features
    • Natural Sciences
    • Physics
      • Matter and Energy
      • Quantum Mechanics
      • Thermodynamics
    • Chemistry
      • Periodic Table
      • Applied Chemistry
      • Materials
      • Physical Chemistry
    • Biology
      • Anatomy
      • Biochemistry
      • Ecology
      • Genetics
      • Microbiology
      • Plants and Fungi
    • Geology and Paleontology
      • Planet Earth
      • Earth Dynamics
      • Rocks and Minerals
      • Volcanoes
      • Dinosaurs
      • Fossils
    • Animals
      • Mammals
      • Birds
      • Fish
      • Amphibians
      • Reptiles
      • Invertebrates
      • Pets
      • Conservation
      • Animal facts
    • Climate and Weather
      • Climate change
      • Weather and atmosphere
    • Health
      • Drugs
      • Diseases and Conditions
      • Human Body
      • Mind and Brain
      • Food and Nutrition
      • Wellness
    • History and Humanities
      • Anthropology
      • Archaeology
      • History
      • Economics
      • People
      • Sociology
    • Space & Astronomy
      • The Solar System
      • Sun
      • The Moon
      • Planets
      • Asteroids, meteors & comets
      • Astronomy
      • Astrophysics
      • Cosmology
      • Exoplanets & Alien Life
      • Spaceflight and Exploration
    • Technology
      • Computer Science & IT
      • Engineering
      • Inventions
      • Sustainability
      • Renewable Energy
      • Green Living
    • Culture
    • Resources
  • Videos
  • Reviews
  • About Us
    • About
    • The Team
    • Advertise
    • Contribute
    • Editorial policy
    • Privacy Policy
    • Contact

© 2007-2025 ZME Science - Not exactly rocket science. All Rights Reserved.