Palaeontology: Seeing stars on the micro scale

Microlenses, seen in starfish and brittle stars, were present on such creatures at least 75 million years ago reports a paper published in Nature Communications this week. This finding suggests that a highly developed visual system similar to modern echinoderms’ date back to the Late Cretaceous period.

Echinoderms such as starfish and sea urchins typically lack an elaborate visual system like the compound eyes of insects. However, it has recently been reported that some brittle stars and starfish have microlenses that function as a compound eye. Yet, the evolutionary origins of these microlenses remain unclear. Przemyslaw Gorzelak and colleagues analysed Late Cretaceous brittle stars and starfish from Poland and observed lens-like microstructures, suggesting that these echinoderms had a highly developed visual system similar to that of modern forms. The team advances that these elaborate eyes could have evolved as a means of escaping predators during a period of large-scale diversification of aquatic predators.