Date of Award

Summer 2003

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Alan Savitzky

Committee Member

Jefferey A. Hinkley

Committee Member

Keith A. Carson

Call Number for Print

Special Collections LD4331.B46 R58 2003


The evolution of the ophidian feeding mechanism has involved substantial morphological restructuring associated with the ability to ingest relatively large prey. Previous studies examining the morphological consequences of macrophagy have concentrated on modifications of the skull and cephalic musculature. Although it is evident that macrophagy requires highly compliant skin, the mechanical properties of the ophidian integument have received limited attention, particularly in the context of feeding. I examined mechanical properties of skin along the body axis in male Thamnophis sirtalis (Colubridae). From each of 11 specimens, I examined nine circumferential strips of skin, each spanning 10 ventral scales, spaced at increments of 10% of the ventral scale count. Each circumferential strip was divided into two samples. One sample was subjected to a uniaxial tensile test along the transverse body axis, to determine circumferential compliance; the other sample was fixed for histological examination. Data were collected from 93 tensile tests and were analyzed using a multivariate analysis of variance (MANOVA) and post hoc multiple comparison tests. Significant differences in mechanical properties were detected among regions of the body. In general, prepyloric skin is more compliant than postpyloric skin, consistent with the demands of macrophagy. Prepyloric skin is also thinner, has more scale rows, and appears to have more intersquamous skin.


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