Starfish Learn Without a Brain: A Surprising Insight into How Echinoderms Adapt
Researchers from Duke University in North Carolina have shown that some starfish species can learn new tasks despite lacking a centralized brain. The findings appeared in the scientific journal Behavioral Ecology and Sociobiology (BES), adding to a growing body of work on how simple nervous systems process experience.
Among the creatures studied was a black brittle star, scientifically named Ophiocoma echinata, a species that thrives in the tropical waters of the Atlantic Ocean and the Caribbean Sea. Compared with animals that possess a brain, these echinoderms rely on a distributed network of nerves located in their limbs, with connections circling the mouth in a rough ring.
According to lead author Julia Notar, the starfish studied do not contain a single control center. Each nerve cord is capable of acting independently, giving the organism a collaborative decision‑making style rather than a command hierarchy. This description helps frame how these animals might process experiences without a central processing unit.
In an experiment, researchers placed 16 brittle stars into water tanks and fed them every half hour. Illumination in the aquarium room varied: a portion of the group fed under dim lights, while another portion fed with the room lights on.
The study extended over ten months, during which the first group began forming a conditioned response to darkness. When the lights were switched off, the brittle stars would emerge from shelter ahead of the arrival of food. The consistent link between darkness and feeding opportunities appeared to rewrite basic expectations in the animals, suggesting a form of learned behavior without a brain.
Even after an interval of 13 days without changes in lighting while feeding, the same pattern persisted. The durability of this conditioned response points to memory mechanisms that can operate within decentralized nervous systems, a finding that broadens our understanding of cognition across species.
Experts note that the exact biological processes enabling memory in brainless organisms remain an area for further investigation. Researchers expect continued experiments to shed light on how distributed neural networks can store and retrieve information from prior experiences.
Prior observations in related research indicate that other simple animals, such as tiny jellyfish with no centralized brain, can also demonstrate learning from past mistakes. These instances collectively invite a broader reconsideration of what learning and memory might look like in diverse life forms.
Overall, the Duke University study adds a compelling chapter to the study of animal intelligence, highlighting that even organisms without a traditional brain may adapt through experience. The work invites ongoing inquiry into how distributed neural systems translate past encounters into future actions, and what these revelations imply about the evolution of cognition across the animal kingdom.
Note: The research described here reflects findings published in peer‑reviewed sources and corroborated by subsequent investigations that continue to explore learning in organisms with minimal centralized control.