Starfish see their way home

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Starfish are known to have`sensors on the ends of their arms, but until recently it wasn't clear whether these were eyes or just light-detecting structures.

But according to new research, these sensors act in the same way as eyes, forming images to help the starfish find their way home.

Scientists from universities in Denmark and Sweden removed the sensors from the arms of a group of starfish and left others untouched. All the starfish were placed on a sandy bottom away from the rocks and researchers watched to see what would happen.

Those starfish which had their sensors intact immediately returned to the rocks, while those whose sensors had been removed scurried off in all directions, apparently unable to work out which direction they were meant to be going in to find the rocks.

Anders Garm from the University of Copenhagen in Denmark, says this demonstrates the starfish need these sensors to find and move towards the reef, showing the sensor is able to form an image of the reef and that the starfish must also be able to process this information.

The eyes of starfish are similar in structure to what scientists believe were the first image-forming eyes and Garm thinks human eyes may first have evolved for a similar reason — to enable us to find our way home.

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