The Loh Down On Science

Do five eyes see better than two?

Can sea stars see stars?

This is Sandra Tsing Loh with the Loh Down on Science.

Most starfish have bug-like eyes at the tip of each arm.  They’re only good for detecting changes in light level.  Or so you’d hope! 

Enter Anders Garm from the University of Copenhagen.  He kidnapped starfish from reefs near Japan.  Then set them free.  But at different locations and distances from the reef.  He filmed their attempts to return home. 

Those placed twelve feet away?  They walked around in circles, never finding their way back.  At six feet?  Half got home, half didn’t.  But at just three feet?  Every single starfish made a beeline to the reef!  Yet when he repeated the three-foot test on a black, moonless night?  They all got lost.  This proved that they use vision, not say, smell, to navigate.  And this means that their eyes form true images.

Granted, lab tests reveal that they’re colorblind.  And see only fuzzy images and general shapes.

Put another way, they won’t see your tan line but will notice those love handles.  Snorkel at your own risk.

***** For more 90-SECOND SCIENCE FACTS, click here.*****

The Loh Down on Science is produced by LDOS Media Lab, in partnership with the University of California, Irvine, and 89.3 KPCC. And made possible by the generous support of the Gordon and Betty Moore Foundation.


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