Duke University researchers, in a recent experiment, observed that these aquatic creatures can learn despite being brainless.
Intelligence, according to us humans in general, is hugely associated with the brain and we even refer to talented people as "brainy." However, a recent study done by researchers at Duke University, Durham shows that even without a brain, learning is possible through experience. An experiment led by Julia Nortar, as part of her biology Ph.D., on a marine species closely related to starfish showed its learning abilities even though it has no head or brain, reports Duke Today.
Hey #SICB2023! I usually talk about urchins but tomorrow (Sat.) I’m talking about brittle stars and their learning. Come through for a new story and some cool/creepy videos!— Julia Notar, PhD (@indy_sea) January 6, 2023
9:15am in Lonestar A, Saturday 1/7 pic.twitter.com/eJuwrgzgOn
Nortar's research, published in Behavioral Ecology and Sociobiology journal, was focused on the headless five-armed aquatic animal called the Brittle Star which is known for spending most of its time hiding under rocks and crevices in the ocean or burrowing in the sand. These creatures don't have centralized control of their nervous system instead their nerve cords run through each of their five arms like the ones posted by her on X.
"There's no processing center, each of the nerve cords can act independently," said Nortar whose research was conducted in her professor Sonke Johnsen's lab at the university along with former graduate Madeline Go and added, "It’s like instead of a boss, there's a committee." The experiment involved recording the behavior of 16 brittle stars (Ophiocoma echinata) in separate water tanks for over 10 months.
Brittle stars don't have brains, but that doesn't stop them from learning! Our new paper from the @sonkelab is out now in Behavioral Ecology & Sociobiology: https://t.co/ZmR9HM64rA #NoBrainNoProblem pic.twitter.com/NMbrmyb2ie— Julia Notar, PhD (@indy_sea) November 30, 2023
The key to the brainless creature's learning is association and the brittle stars associate different stimuli through a process called 'classic conditioning.' Previously this association was studied by Russian scientist Ivan Pavlov on dogs. He caused the canines to associate a bell sound with mealtime and observed how the dogs started salivating when they heard the bell sound irrespective of the provision of food. Nortar who is also specialized in studying sea urchins decided to apply this conditioning to the brittle stars too.
One-half of the brittle stars in the tanks were fed morsels of shrimp (their favorite meal) in a dark environment where the lights were dimmed for 30 minutes. The other half also experienced a 30-minute dark setting but were fed the same treats only in a brightly lit environment. As a result, though most of the animals tested were hiding behind the tanks' filters and came out just when they were being fed, the brittle stars trained to feed under dim lights associated darkness with mealtime.
Just by sensing the dim lights, they figured out that the meal was being served even when they didn't smell or taste the shrimp. The surprising fact was that these marine creatures remembered the association even after a 13-day break. "Knowing that brittle stars can learn means they’re not just robotic scavengers like little Roombas cleaning up the ocean floor," said Nortar and added, "They're potentially able to expect and avoid predators or anticipate food because they’re learning about their environment."
The researcher posted on X about this fascinating discovery and hopes to discover more secrets behind the brittle stars' learning despite having no processing center like humans. "People ask me all the time, 'How do they do it?'" said Nortar and added, "We don't know yet. But I hope to have more answers in a few years."