Left, maxillary teeth of the brown tree snake, Boiga
irregularis penetrating the integument of a young rodent.
Note groove in the one (right), non-grooved tooth (left).
The morphology of snake teeth is correlated with the physical
properties of prey skin and the mechanical processes in which
the teeth participate during prey capture and swallowing. First
we examine the mechanical problems teeth encounter during
piercing and cutting. Second we correlate features of snake
teeth with these mechanical demands. Most prey skin is a
feltwork of collagen that acts like a compliant elastomer that
yields when stressed. A comparison of shapes indicates that
sharp, slender objects serve best to penetrate and enter such
elastomers, not by use of frictional forces but instead by
concentration of `forces. Similarly, blade-like edges take
advantage of force concentrations, not friction, to produce
damaging tensile and shear forces within the collagen feltwork
when cutting skin. Delivery of oral secretions is best served by
enclosed channels protecting flow of fluid. Analysis of second
moments of area indicate that grooves in teeth actually weaken
the bending strength of the tooth. The implications the design
of snake teeth are several. Piercing and entry of compliant prey
is served by sharp, slender teeth oriented with tips coincident
with the angle of approach to the skin. Raised enamel ridges on
tooth tips facilitate entry. Extended ridges along snake teeth
contribute to effective cutting, and such blade-like teeth are
usually placed at the most advantages geometric position
(posterior maxillary bone) to be deployed during swallowing.
Grooves in teeth do not increase bending strength and, being
open, expose fluid flow to interruption by the surface of the
prey. Grooved and furrowed teeth are hypothesized to facilitate
fluid flow to the surface of the prey and/or to change the
frictional properties of the tooth surface.
See: Kardong, K. V. and B. A.
Young. 1999. Tooth structure in snakes: mechanical and
functional significance.
Other References |