Starfish on ocean floor found to have well developed eyes

first_imgA team of researchers from the University of Copenhagen and the Greenland Institute of Natural Resources has found that starfish living in the dark on the ocean floor have eyes on their arms that are similar to other starfish living near shore. In their paper published in Proceedings of the Royal Society B, the group describes their study of the unique sea creatures and what they learned about starfish vision. More information: Deep-sea starfish from the Arctic have well-developed eyes in the dark, Proceedings of the Royal Society B (2018). Published 7 February 2018.DOI: 10.1098/rspb.2017.2743 ,” alt=”center_img” /> Scientists have known for some time that some starfish that live near shore have compound eyes in the tips of their arms. In this new study, the researchers have found the same to be true for many types of starfish that live in the dark at the bottom of the ocean.To learn more about starfish vision in places besides the shoreline, the researchers collected hundreds of specimens (representing 13 species) from depths ranging from shallow waters to 1,000 meters below the surface—all living in the North Atlantic near Greenland. They found that 12 of the species had compound eyes similar to those found in starfish near the shoreline—the one lone species without eyes was a burrowing starfish that lives relatively close to shore.In all of those with compound eyes, the eyes were uncovered, the researchers report, and were located on the bottom side of the arm tip, which means the starfish bend the tips to use them, pointing the eyes at targets. Visual acuity and sensitivity to light varied among the species they studied.The team also noted that two of the species were also bioluminescent, able to emit flashes of light. Because they have both vision and a means for producing light, the researchers suggest the bioluminescence could be a means of communication between members of the same species—perhaps as a signal warning of predators or as part of mating. They note more study is required to learn how the starfish actually use both their eyes and bioluminescence, but also point out the difficulty in doing so. Studying a sea creature on the ocean floor in the dark requires specialized equipment and perhaps a light source, which changes the environment, inhibiting the observation of natural behavior. Journal information: Proceedings of the Royal Society B This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Explore furtherlast_img read more

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