The young palaeontologists Przemysław Gorzelak, PhD (Institute of Paleobiology of the Polish Academy of Sciences, 2009 and 2010 FNP START programme beneficiary), Mariusz Salamon, PhD hab. (University of Silesia, 2005 and 2006 START programme beneficiary), along with mgr Rafał Lach (University of Silesia), mgr Michał Loba (University of Warsaw) and Bruno Ferré, PhD (Sotteville-lès-Rouen, France), are the authors of groundbreaking research results that have been published in the latest issue of the multidisciplinary magazine Nature Communications. Next to Nature, Science and PNAS, this publication is one of the most opinion-forming in the world of science.
The Polish palaeontologists’ research proved that the compound eyes of echinoderms (marine invertebrates usually with a five-point radial symmetry, including sea urchins, starfish and brittle stars) appeared in the Cretaceous period, i.e. 80 million years ago (compound eyes are a specific type of eye formed from lenses arranged in a characteristic mosaic pattern). In their article in Nature Communications, they described the oldest fossilised echinoderm remains which possess lenses arranged in a mosaic. The scientists suggest that the appearance of optical organs in these echinoderms was a response to the growing pressure from predators in the Cretaceous. “The appearance of complex eyes during evolution without doubt allowed echinoderms to escape the attack of predators more easily,” the authors claim.
Publication of the results is an important development in research on this type of optical structures. We know that such eyes make it possible to perceive light intensity, but usually do not permit sharp perception of shapes. Recent research under the leadership of Joanna Aizenberg of the Weizmann Institute in Israel published in Nature showed that similar optical structures to those in insects are also evident in other invertebrates, including in some species of echinoderms. This research proved that the so-called compound eyes of contemporary echinoderms are built from a series of microlenses arranged in a mosaic constructed from calcium carbonate (CaCO3). These lenses are surrounded with pigment-filled cells, which absorb most light rays, only allowing perpendicular ones into the lenses. Thanks to the exceptional optical characteristics of these microlenses, which are light, durable and do not cause splitting of the light ray or deformation of the resultant image, they are of interest to researchers of biomimetics – a science which aims to exploit the construction and processes observed in organisms in technical sciences.
Over: Lenses of contemporary echinoderms (photo: Przemysław Gorzelak).
Below: Fossilised lenses of echinoderms from 80 million years ago discovered in Rzeżuśnia near Miechów, southern Poland (photo: Przemysław Gorzelak).