Get to the point: Claw morphology impacts frictional interactions on rough substrates

Alexandra M. Pamfilie, Austin M. Garner, Anthony P. Russell, Ali Dhinojwala, Peter H. Niewiarowski

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Claws are a common anatomical feature among limbed amniotes and contribute to a variety of functions including prey capture, locomotion, and attachment. Previous studies of both avian and non-avian reptiles have found correlations between habitat use and claw morphology, suggesting that variation in claw shape permits effective functioning in different microhabitats. How, or if, claw morphology influences attachment performance, particularly in isolation from the rest of the digit, has received little attention. To examine the effects of claw shape on frictional interactions, we isolated the claws of preserved specimens of Cuban knight anoles (Anolis equestris), quantified variation in claw morphology via geometric morphometrics, and measured friction on four different substrates that varied in surface roughness. We found that multiple aspects of claw shape influence frictional interactions, but only on substrates for which asperities are large enough to permit mechanical interlocking with the claw. On such substrates, the diameter of the claw's tip is the most important predictor of friction, with narrower claw tips inducing greater frictional interactions than wider ones. We also found that claw curvature, length, and depth influence friction, but that these relationships depend on the substrate's surface roughness. Our findings suggest that although claw shape plays a critical role in the effective clinging ability of lizards, its relative importance is dependent upon the substrate. Description of mechanical function, as well as ecological function, is critical for a holistic understanding of claw shape variation.

Original languageEnglish (US)
Article number126078
StatePublished - Apr 2023
Externally publishedYes


  • Anolis
  • Biomechanics
  • Function
  • Morphometrics
  • Surface topography

ASJC Scopus subject areas

  • Animal Science and Zoology


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