News Animals

Crabs’ sideways walk may have evolved just once

Crabs that inherited the trait are far more species-rich, suggesting it fueled their success

A crab scurries sideways along a beach in the United Arab Emirates. Scientists have traced this distinctive gait to a single ancestor that lived roughly 200 million years ago.

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By Sierra Bouchér

The iconic sideways walk of crabs may have evolved just once, in an ancestor that roamed Earth roughly 200 million years ago.