All in their heads

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Laurent Formery

Starfish seem like creatures of many limbs—but it turns out they’re just heads. In a growing young starfish, or sea star, the genetic signs for “head” are nearly everywhere, researchers found, while genes encoding torso and tail are largely absent. “It’s as if the sea star is completely missing a trunk, and is best described as just a head crawling along the seafloor,” said Laurent Formery, a postdoctoral researcher at the University of California, Berkeley, and lead author of the new study.

Most animals feature a familiar head-to-tail body plan, making the starfish a puzzling outlier and object of scientific fascination. High-tech molecular methods, including fluorescent staining (pictured), revealed the starfish’s hidden heady nature. Next, researchers want to see if sea cucumbers and sea urchins have the same head-driven genetic programming.

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