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

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.

Source: Proceedings of the Royal Society B: Biological Sciences - January 24, 2018 Category: Biology Authors: Sumner-Rooney, L., Rahman, I. A., Sigwart, J. D., Ullrich-Lüter, E. Tags: behaviour, physiology, evolution Morphology and biomechanics Source Type: research