Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Echinobase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
Echinobase
ECB-ART-46092
Proc Biol Sci 2018 Jan 31;2851871:. doi: 10.1098/rspb.2017.2590.
Show Gene links Show Anatomy links

Whole-body photoreceptor networks are independent of ''lenses'' in brittle stars.

Sumner-Rooney L , Rahman IA , Sigwart JD , Ullrich-Lüter E .


Abstract
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 might form a sophisticated compound eye-like system regulated by chromatophores has been extensively reiterated, with investigations into biomimetic optics and similar supposedly ''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 hypothesized 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.

PubMed ID: 29367398
PMC ID: PMC5805950
Article link: Proc Biol Sci



References [+] :
Aizenberg, Calcitic microlenses as part of the photoreceptor system in brittlestars. 2001, Pubmed, Echinobase