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Carl Gans and Kim Hyung L.

Computerized analysis of the sidewinding locomotion of four vipers provides a general overview of the locomotive pattern as well as permits us to emphasize similarities and differences among the species. Interspecific variations mainly affect the head and tail. As most of the kinetic energy is generated in the midportions, such differences have minimal effect. The displacement pattern, kinetic energy value and the placement of tracks change as an animal changes its direction of travel by moving its center of gravity out of line with sites of static contact.

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Henry R. Mushinsky and Carl Gans

Abstract

Thirteen sand skinks, Neoseps reynoldsi, were observed and videotaped traversing variously spaced plexiglass channels and spacings of pins to investigate locomotory patterns of a slender elongate lizard, with reduced limbs. Five individuals were recorded both before and after tail autotomy. Neoseps moves its limbs in locomotion on a flat surface; the hindlimbs participate in propulsion and their position, relative to their body, reflects the curvature of the trunk. Distance between pins, width of the plexiglass channel, and surface texture influence locomotory patterns. Individuals move more rapidly in wide channels, and movement is most irregular in channels with sandpaper floors. Whether on a plexiglass or a sandpaper floor, individuals travel more rapidly down the 2cm wide channel than the 1 cm channel. Fewer bends in the trunk in the wider channels may allow for more rapid movement. Autotomy of the tail slows movement on a plexiglass or sandpaper floor. The anterior portion of the tail contributes to the establishment of a static friction site that is jerked toward the head during locomotion, advancing the center of gravity in that direction. From the new site the trunk can be straightened by pushing against the friction site. The posterior portion of a tailless individual slides backward as the trunk is straightened, slowing their forward movement. The backward slide may reflect the lower mass and reduced static friction of the partial tail. In channels, Neoseps uses limbed concertina rather than simple concertina to generate a propulsive force. Evolutionarily, it appears that elongation of the tail and trunk did not incorporate the capacity for lateral undulation; as the curves of the trunk and tail seem preprogrammed and do not adjust to local points of contact.

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W.F.C. Blumer, Carl Gans and R. Merlin

Abstract

The Australian desert lizard, Moloch, has been reported to collect water by aposing its body to wet surfaces. This water passes through small open capillary channels over the integumentary surface to reach the mouth where it is swallowed. Experiments and scanning micrographs show that water collection and water transport are more complex and occur in different regions of the integument than described. Observations on other agamids from the same region indicate the extent to which agamid skin generally permits water passage; they allow a better definition of the specializations of Moloch.