Right-handed snakes: Convergent evolution of asymmetry for functional specialization

Masaki Hoso*, Takahiro Asami, Michio Hori

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

104 Citations (Scopus)


External asymmetry found in diverse animals bears critical functions to fulfil ecological requirements. Some snail-eating arthropods exhibit directional asymmetry in their feeding apparatus for foraging efficiency because dextral (clockwise) species are overwhelmingly predominant in snails. Here, we show convergence of directional asymmetry in the dentition of snail-eating vertebrates. We found that snakes in the subfamily Pareatinae, except for non-snail-eating specialists, have more teeth on the right mandible than the left. In feeding experiments, a snail-eating specialist Pareas iwasakii completed extracting a dextral soft body faster with fewer mandible retractions than a sinistral body. The snakes failed in holding and dropped sinistral snails more often owing to behavioural asymmetry when striking. Our results demonstrate that symmetry break in dentition is a key innovation that has opened a unique ecological niche for snake predators.

Original languageEnglish
Pages (from-to)169-173
Number of pages5
JournalBiology Letters
Issue number2
Publication statusPublished - 2007 Apr 22
Externally publishedYes


  • Handedness
  • Land snails
  • Laterality
  • Molluscivore
  • Parallel evolution

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Agricultural and Biological Sciences(all)


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