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Acontias percivali, JCM
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Limblessness has evolved numerous
times in squamates and as it does it limits the animal’s abilities in a variety
of ways. Limbless lizard species are usually grass or litter swimmers or they
burrow. Burrowing head first may limit the head size, and therefore limit the
bite force of the animal. The consequences of this may be more important to
males that compete for mates using combat. Burrowing rapidly may be important
in escaping a predator, but it means a narrower head and loss of bite force. Bieke
Vanhooydonck and colleagues have investigated how loss of legs affects the
ability to burrow using the legless African skink Acontias percivali (Scincidae,
Acontiinae). They used an ingenious device to measure burrowing force that
positioned the lizard in a plastic tunnel so that it would push its head into
soil in a box mounted on a force plate. They measured bite force using an
isometric Kistler force transducer. Their results suggest that A. percivali uses a burrowing style that
involves the skink’s entire body to generate force, peak force was generated by
total length. They also found both bite force and the time needed to burrow
into the substrate were determined by relative head width, suggesting a
trade-off between biting and burrow speed. Performance data were indeed suggestive
of a correlation between bite force and the time needed to burrow, but
additional data are needed to confirm this pattern. Trade-offs apparently do
occur and may have been important in shaping the head during the evolution of A. percivali, and other burrowing species.
Citation
Vanhooydonck, B.,
R, Boistel, V. Fernandez, A. Herrel. 2011. Push and bite: trade-offs between
burrowing and biting in a burrowing skink (Acontias
percivali). Biological Journal of
the Linnean Society 102:91–99.
