Starless Starfish

May 30, 2011

A starfish without arms makes scientists rethink how they classify animals.

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Transcript

BOB HIRSHON (host):

Starless starfish…I’m Bob Hirshon and this is Science Update.

In the 1980s, researchers discovered a marine organism living on timbers that had fallen to the sea floor, nearly a mile below the surface. They thought the animal, called xyloplax, or sea daisy, represented a whole new class of echinoderms. But DNA analysis by computational biologist Dan Janies of Ohio State University and his colleagues instead revealed that xyloplax are actually a type of armless starfish.

DAN JANIES (The Ohio State University):

It’s in fact just a strange starfish.

HIRSHON:

He says the lack of arms is deceptive, but an adult xyloplax actually resembles a juvenile starfish.

JANIES:

What evolution has done here is truncated the life cycle. So we have a juvenile size and shape animal that has adult reproductive organs.

HIRSHON:

He says the discovery highlights the importance of using DNA to correctly classify enigmatic organisms. I’m Bob Hirshon, for AAAS, the science society.