Julia Notar’s research at Duke University has uncovered that brittle stars, despite having no brains, possess the ability to learn through their experiences. These ocean dwellers, relatives of starfish, rely on their nerve cords for associative learning, a principle evident in classical conditioning.
Despite their absence of a brain, brittle stars demonstrate the capacity to learn experientially, a finding highlighted in recent research. They have been shown to associate darkness with feeding times, marking a notable advancement in our understanding of learning mechanisms in brainless sea organisms.
The human tendency to equate intelligence with large brains is challenged by these brainless organisms. Brittle stars, devoid of brains, still exhibit learning abilities, as the latest research indicates.
Closely related to starfish, these creatures spend their time concealed under rocks and within crevices of the ocean, or burrowing in sand.
Lacking a central brain, brittle stars possess nerve cords extending along their five flexible arms, converging into a nerve ring near their mouth.
Julia Notar, who conducted this study as part of her biology doctorate in Sönke Johnsen’s lab at Duke University, notes, “There’s no central control unit, rather, the nerve cords function independently, akin to a committee rather than a single boss.”
In experiments, brittle stars learned to associate the dimming of lights with feeding times. Credit goes to Julia Notar for this discovery.
Deciphering Learning in Brain-Free Marine Life
According to Notar, Johnsen, and former Duke undergraduate Madeline Go’s report in the journal Behavioral Ecology and Sociobiology, brittle stars can learn by associating different stimuli, a process known as classical conditioning, exemplified by Pavlov’s dog experiments.
Humans experience this regularly. For instance, repeatedly hearing a smartphone’s “ding” can imbue the sound with special significance. Even the ping from another person’s phone can trigger a reflexive check of one’s own phone in anticipation of a message or update.
Classical conditioning has been previously demonstrated in starfish in a few studies. However, most echinoderms, a group comprising about 7,000 species including brainless brittle stars, starfish, sea urchins, and sea cucumbers, have not been extensively studied in this context.
To test if brittle stars can learn, researchers placed 16 black brittle stars (Ophiocoma echinata) in separate tanks, observing them with video cameras.
A time-lapse video from Duke University researchers showcases an experiment on whether brainless brittle stars could learn. Each time the lights dimmed, a pipette with shrimp, their preferred food, was introduced into their tanks. Eventually, the animals learned to associate the dimming of lights with mealtime.
In the training, half the brittle stars were fed whenever the lights were dimmed for 30 minutes. Whenever the lights went out, shrimp pieces were placed just out of their reach.
The control group received equal amounts of shrimp but was fed under lit conditions, with no association with the dark periods.
Initially, the animals remained hidden during darkness. But over time, they associated darkness with feeding and emerged from hiding when the lights dimmed, even before food was introduced.
These brittle stars had formed a new association: darkness indicated the likely arrival of food. They responded to the dimming lights without needing to smell or taste the shrimp.
Exploring Learning and Memory in Echinoderms
Even after a 13-day training hiatus, the brittle stars retained this learned association.
Notar expressed excitement over these findings, as classical conditioning had not been definitively shown in this animal group before.
This discovery suggests that brittle stars are not merely robotic ocean floor cleaners but can potentially anticipate food and avoid predators due to their learning capabilities.
Notar aims to further explore how these animals learn and remember using a nervous system vastly different from ours.
“People often ask, ‘how do they manage this?'”, says Notar. “While the answer is still unknown, more insights are expected in the coming years.”
The research, published as “Learning without a brain: classical conditioning in the ophiuroid Ophiocoma echinata” by Julia C. Notar, Madeline C. Go, and Sönke Johnsen on 21 November 2023 in Behavioral Ecology and Sociobiology, was supported by the U.S. Department of Defense through the National Defense Science & Engineering Graduate Fellowship Program, the Duke Nicholas School Rachel Carson Scholars program, and the Duke Biology Department.
Table of Contents
Frequently Asked Questions (FAQs) about Brittle Star Learning
What did the research on brittle stars at Duke University discover?
The study led by Julia Notar at Duke University found that brittle stars, despite lacking a brain, are capable of learning through experience. This is achieved through associative learning, a form of classical conditioning, where they associate darkness with feeding times.
How do brittle stars learn without a brain?
Brittle stars use their nerve cords, which run down each of their arms and connect in a nerve ring near their mouth, for learning. This system allows them to learn by association, a method proven in classical conditioning, without a central processing center.
What is the significance of the brittle star learning discovery?
This discovery is significant as it challenges the traditional view that a large brain is necessary for learning and intelligence. It provides new insights into the learning processes of brainless marine creatures and expands our understanding of intelligence in the animal kingdom.
What method was used to demonstrate learning in brittle stars?
Researchers conducted classical conditioning experiments where they trained brittle stars to associate the dimming of lights with feeding times. Over time, the brittle stars learned to emerge from hiding in anticipation of food when the lights dimmed.
What future research is planned following this discovery?
Following this discovery, further research is planned to understand how brittle stars manage to learn and remember using their unique nervous system. This research aims to uncover more about the mechanisms of learning and memory in animals with nervous systems different from humans.
More about Brittle Star Learning
- Brittle Stars’ Learning Abilities
- Julia Notar’s Research at Duke University
- Marine Creatures and Learning Processes
- Classical Conditioning in Marine Biology
- Nerve Cord Function in Brittle Stars
- Associative Learning in Brain-Free Marine Life
- Echinoderms and Learning Studies
- Classical Conditioning Experiment on Brittle Stars
- Discovering Memory in Echinoderms
5 comments
Brittle stars are so underrated, they’re proving to be way more intelligent than we thought. This research is groundbreaking!
kinda hard to believe, how do they even manage that without a central brain? science is just blowing my mind.
This is fascinating! i never knew marine life could be so complex especially without a brain, Great work by the Duke team.
I always thought learning needed a brain, this changes everything. But can they remember stuff for long? Curious to know more.
wow just amazing how these creatures can learn without even a brain, really makes you think about intelligence in a whole new way!