Walking coral: Complex phototactic mobility in the free-living coral <em>Cycloseris cyclolites</em>

Not all corals are attached to the substrate; some taxa are solitary and free-living, allowing them to migrate into preferred habitats. However, the lifestyle of these mobile corals, including how they move and navigate for migration, remains largely obscure. This study investigates the specific biomechanics of Cycloseris cyclolites, a free-living coral species, during phototactic behaviour in response to blue and white light stimuli. Our results indicate a strong positive phototactic response to blue light, with 86.7% (n=15) of samples moving towards the light source, while only 20% (n = 15) of samples responded similarly to white light (400-700 nm). Locomotion, characterised by periodic pulses lasting 1-2 hours, involved distances up to 220 mm in blue light trials, whereas significantly shorter distances were observed in white light trials. Trails with two light sources reinforced the preference for blue light over white, with all samples consistently moving towards the blue light and..., Trials were performed using either a white light source (shallow water; ~ 420nm to ~ 755nm, PAR 115 to 120 µmol m-2s-1) or a blue light source (deeper water; ~ 460nm, PAR 115 to 120 µmol m-2s-1). Spectral quality was measured using a CL-S10w spectroradiometer (Konica Minolta, Tokyo, Japan) (Fig 1) while intensity was recorded in available photosynthetically active radiation (PAR) and measured using the Underwater Quantum Flux reader (Apogee, North Logan, Utah), on the floor of the aquarium directly under the openings for light. Individuals of C. cycloseris were placed at the shaded end (opposite to the end with the opening) and 1 to 3cm from the aquarium walls to avoid interaction with adjacent surfaces. Measuring distance travelled To quantify distance travelled and frequency of mobilisation over 24 hours, time-lapse videos (n = 16) were recorded using an iPad (Apple Inc., USA) at a resolution sufficient for tracking movement, with playback set at 30 fps. The experiment consisted of 16..., , # Data from: Walking coral: Complex phototactic mobility in the free-living coral *Cycloseris cyclolites* [https://doi.org/10.5061/dryad.sj3tx96dw](https://doi.org/10.5061/dryad.sj3tx96dw) ## Description of the data and file structure ### Files and variables #### File: Coral_Walking_Accumulative_Raw_Measurements.xlsx **Data: Raw values, distances travelled during the trials** **Description:** Not all corals are attached to the substrate; some taxa are solitary and free-living, allowing them to migrate into preferred habitats. However, the lifestyle of these mobile corals, including how they move and navigate for migration, remains largely obscure. This study investigates the specific biomechanics of *Cycloseris cyclolites*, a free-living coral species, during phototactic behaviour in response to blue and white light stimuli. Our results indicate a strong positive phototactic response to blue light, with 86.7% (n=15) of samples moving towards the light source, while only 20% (n = 1..., ,