When Did Crabs Evolve Their Iconic Sideways Scuttle? Scientists Traced It to a 200-Million-Year-Old Common Ancestor
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Scientists have traced the evolution of crabs' iconic sideways scuttle to a common ancestor that lived around 200 million years ago. This movement likely evolved just once and has contributed to the ecological success of true crabs. The study highlights the unique nature of this locomotion compared to other evolutionary traits.
- ▪The sideways scuttle evolved in a single ancestor at the base of the subgroup Eubrachyura.
- ▪There are approximately 8,000 species of true crabs, with Eubrachyura being the most advanced and diverse group.
- ▪The sideways locomotion may have helped crabs escape predators and adapt to various environments.
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When Did Crabs Evolve Their Iconic Sideways Scuttle? Scientists Traced It to a 200-Million-Year-Old Common Ancestor The findings suggest that their famous lateral movement evolved just once. It may have helped the animals rapidly spread and diversify because traveling in two directions meant they could easily escape predators Sara Hashemi | Daily Correspondent May 20, 2026 11:57 a.m. ShareCopy linkEmailSMSFacebookXRedditLinkedInBlueskyPrintAdd as preferred source Tuerkayana hirtipes, a true crab species examined in the study Tsubasa Inoue Many crabs are famous for their sideways shuffle, but little is known about how this movement evolved. Now, scientists have traced the history of their iconic walk to a common ancestor that lived roughly 200 million years ago.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Smithsonian Magazine.
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