- Box jellyfish do not have brains — yet, a new study shows they are still capable of learning.
- Researchers over time managed to train box jellyfish to avoid obstacles in a low-light environment.
Known for carrying heart-stopping venom that can kill a person in 15 minutes, and for their ability to grow up to 10 feet long, box jellyfish have quite the reputation.
Now, researchers have discovered the killer creatures are actually capable of learning, despite not having brains.
A team of marine scientists published an article on Friday in Current Biology, a peer-reviewed journal, revealing that a species of box jellyfish can learn and change their behavior solely based on visual and mechanical stimulation. That means they learn through their nervous system and do not need a brain to form these connections.
This discovery challenges the long-held idea that associative learning requires a brain, according to the study.
Researchers demonstrated this by setting up obstacles for these jellyfish, using stripes to represent the mangrove roots they would need to navigate in the real world.
Researchers placed the creatures in buckets with black and white stripes representing the roots and the water. At optimal brightness, the jellyfish did not run into these obstacles because they could see clearly, according to the study. But when researchers lowered the contrast over time, the number of collisions went up.
"The hypothesis was, they need to learn this," Anders Garm, an author on the paper, told The New York Times on Friday. "When they come back to these habitats, they have to learn, how is today's water quality? How is the contrast changing today?"
The jellyfish did indeed learn. The number of collisions went down over time because the jellyfish learned by combining mechanical stimuli — that is, the sensation of running into obstacles — and visual stimuli.
Garm told the Times this research could help answer the question of whether the learning is universal for organisms with nervous systems.