Scientists Trace Crabs' Sideways Walk to 200 Million-Year-Old Ancestor
Researchers have uncovered new insights into the evolution of crabs' distinctive sideways movement, tracing it back to a common ancestor from approximately 200 million years ago. The study, published in eLife, analyzed the locomotion of 50 species of true crabs, revealing that sideways walking likely evolved once in the evolutionary history of crabs. This movement style, which is a hallmark of the Brachyura group, offers significant advantages such as unpredictable movement patterns that help evade predators. The research team, led by Yuuki Kawabata from Nagasaki University, used video recordings and phylogenetic data to map the evolutionary trajectory of crab locomotion. The findings suggest that while body shapes in crabs have evolved multiple times, the behavioral trait of sideways walking is a rare evolutionary innovation. 
