Non-invasive investigation of the morphology and optical properties of the upside-down jellyfish Cassiopea with optical coherence tomography

The jellyfish Cassiopea largely cover their carbon demand via photosynthates produced by microalgal endosymbionts, but how holobiont morphology and optical properties affect the light microclimate and symbiont photosynthesis in Cassiopea remain unexplored. Here, we use optical coherence tomography (OCT) to study the morphology of Cassiopea medusae at high spatial resolution. We include detailed 3D reconstructions of external micromorphology, and show the spatial distribution of endosymbionts and white granules in the bell tissue. Furthermore, we use OCT data to extract inherent optical properties from light-scattering white granules in Cassiopea, and show that white granules enhance local light-availability for symbionts in close proximity. Individual granules had a scattering coefficient of µs = 200-300 cm-1, and scattering anisotropy factor of g = 0.7, while large tissue-regions filled with white granules had a lower µs = 40-100 cm-1, and g = 0.8-0.9. We combined OCT information with ..., , .oct datafiles included in this repository are to be used with the software \"ThorImage OCT\" from Thorlabs GmbH. All data provided here were acquired with ThorImage OCT version 5.1.2.0.
For people without access to the ThorImage OCT software all data files are also provided in a .tiff format to be used in ImageJ., # Non-invasive investigation of the morphology and optical properties of the upside-down jellyfish Cassiopea with optical coherence tomography:

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## Description of the Data and file structure

This dataset includes raw OCT data files of the animals and morphological structures presented in the manuscript published.

Files are provided in two formats:

1. in the original raw .OCT data files as generated using the ThorImageOCT version 5.1.2.0 software provided for users of the Thorlabs Ganymede OCT system.
2. in 32-bit .tiff file format to be opened in ImageJ. This file format is for people that do not have access to the ThorImageOCT software, and contains all the raw data information as the original files, but lacks the complete 3D view function and additional features of the ThorImageOCT software.

All files uploaded here represent the raw data of 2D and 3D scans of intact *Cassiopea* jellyfish, as well as cut-out regions of select tissue regions, used for this study (figures 1-5 a...