DOI: 10.5061/dryad.kc041
title: Data from: Whole-body photoreceptor networks are independent of ‘lenses’ in brittle stars

description: Photoreception and vision are fundamental aspects of animal sensory
 biology and ecology, but important gaps remain in our understanding of
 these processes in many species. The colour-changing brittle star
 Ophiocoma wendtii is iconic in vision research, speculatively possessing a
 unique whole-body visual system that incorporates information from nerve
 bundles underlying thousands of crystalline ‘microlenses’. The hypothesis
 that these form a sophisticated compound eye-like system regulated by
 chromatophore movement has been extensively reiterated, with consequent
 investigations into biomimetic optics and similar ‘visual’ structures in
 living and fossil taxa. However, no photoreceptors or visual behaviours
 have ever been identified. We present the first evidence of photoreceptor
 networks in three Ophiocoma species, both with and without microlenses and
 colour-changing behaviour. High-resolution microscopy,
 immunohistochemistry and synchrotron tomography demonstrate that putative
 photoreceptors cover the animals’ oral, lateral, and aboral surfaces, but
 are absent at the hypothesised focal points of the microlenses. The
 structural optics of these crystal ‘lenses’ are an exaptation and do not
 fulfil any apparent visual role. This contradicts previous studies, yet
 the photoreceptor network in Ophiocoma appears even more widespread than
 previously anticipated, both taxonomically and anatomically.
description: Sumner-Rooney et al.
 S1Arm
 segments from Ophiocoma wendtii. The 3D data included here were generated
 from x-ray tomography scans of specimens of brittle stars Ophiocoma
 wendtii, Ophiocoma echinata and Ophiocoma pumila. For full methodology,
 please refer to the Method Details text. All models are downsized for
 practicality in PDF form; STL files with full detail are available on
 request. 3D files require Adobe Acrobat or Acrobat Reader (v. 7 or higher)
 for full interactive functionality. Use left-click to rotate, Ctrl+click
 to pan, and shift+click to zoom. Default view is the dorsal
 surface.Sumner-Rooney et al.
 S2Arm
 segments from Ophiocoma echinata. The 3D data included here were generated
 from x-ray tomography scans of specimens of brittle stars Ophiocoma
 wendtii, Ophiocoma echinata and Ophiocoma pumila. For full methodology,
 please refer to the Method Details text. All models are downsized for
 practicality in PDF form; STL files with full detail are available on
 request. 3D files require Adobe Acrobat or Acrobat Reader (v. 7 or higher)
 for full interactive functionality. Use left-click to rotate, Ctrl+click
 to pan, and shift+click to zoom. Default view is the dorsal
 surface.Sumner-Rooney et al.
 S3Arm
 segments from Ophiocoma pumila. The 3D data included here were generated
 from x-ray tomography scans of specimens of brittle stars Ophiocoma
 wendtii, Ophiocoma echinata and Ophiocoma pumila. For full methodology,
 please refer to the Method Details text. All models are downsized for
 practicality in PDF form; STL files with full detail are available on
 request. 3D files require Adobe Acrobat or Acrobat Reader (v. 7 or higher)
 for full interactive functionality. Use left-click to rotate, Ctrl+click
 to pan, and shift+click to zoom. Default view is the dorsal
 surface.Ophiocoma echinata
 1Image stack generated by
 synchrotron scan of Ophiocoma echinata arm segments. Cropped for import
 and reconstruction.Ophiocoma echinata
 2Image stack generated by
 synchrotron scan of Ophiocoma echinata arm segments. Cropped for import
 and reconstruction.Ophiocoma echinata
 3Image stack generated by
 synchrotron scan of Ophiocoma echinata arm spine. Cropped for import and
 reconstruction.Ophiocoma pumila
 1Image stack generated by
 synchrotron scan of Ophiocoma pumila arm segments. Cropped for import and
 reconstruction.Ophiocoma pumila
 2Image stack generated by
 synchrotron scan of Ophiocoma pumila arm segments. Cropped for import and
 reconstruction.Ophiocoma pumila
 3Image stack generated by
 synchrotron scan of Ophiocoma pumila pair of arm spines. Cropped for
 import and reconstruction.Ophiocoma wendtii
 1Image stack generated by
 synchrotron scan of Ophiocoma wendtii arm segments. Cropped for import and
 reconstruction.Ophiocoma wendtii
 2Image stack generated by
 synchrotron scan of Ophiocoma wendtii arm segments. Cropped for import and
 reconstruction.Ophiocoma wendtii
 3Image stack generated by
 synchrotron scan of Ophiocoma wendtii arm segments. Cropped for import and
 reconstruction.