Directional control in sea star locomotion with respect to light

Sea stars control hundreds of tube feet to navigate their environment with a rudimentary nervous system. Tube feet are capable of responding to stimuli without descending nervous commands and it is therefore unclear to what extent tactic orientation emerges through the collective action of the feet or is guided by central control. We therefore performed behavioral experiments to test models of neuromechanical control in a sea star (Protoreaster nodosus). We found that animals moved rapidly along relatively straight trajectories when exposed to light, but slowly crawled along circuitous paths in random directions in the dark. To remove mechanical interactions with the substrate, we measured the kinematics of tube feet in inverted sea stars that exhibited crawling when in contact with the water’s surface. The tube feet throughout the body of these animals moved with power strokes in a similar direction when the animals were exposed to light, which i..., The study investigated directional control in the tube feet of sea stars (Protoreaster nodosus) through experimental manipulation. Specifically, it examined the coordination of tube feet in response to light, both with and without mechanical coupling. The effects of directional stimuli were analyzed using kinematic assessments of individual sea stars. This repository contains the data, MATLAB, and R scripts used for all analyses in the study., , # seastar\_phototaxis

Dryad DOI link: [https://doi.org/10.5061/dryad.b2rbnzsr9](https://doi.org/10.5061/dryad.b2rbnzsr9)

It remains unclear how hundreds of tube feet on sea stars coordinate their movements without a brain. Our research article investigates the behavior of Protoreaster nodosus—specifically, how its tube feet coordinate under different conditions. Previous evidence suggests that tube feet may coordinate through mechanical coupling with the body and substrate, although it is also possible that motor commands from the nervous system drive their coordination.

To test these possibilities, we designed an experiment to minimize mechanical coupling. We inverted the sea stars while providing a directional light stimulus. If the tube feet can still coordinate effectively in the inverted position, it would support the hypothesis that directional coordination is primarily
a result of nervous system control rather than mechanical coupling.

Our findings indicate that mechanical c...,