Posted by:
RMB
at Mon Jan 29 13:44:25 2007 [ Email Message ] [ Show All Posts by RMB ]
Chrysemys sp. have growth rings, too. As in most aquatic turtles, they are noticeable for many years. They are less noticeable (or not evident at all) in adult painteds and adult box turtles, since growth may have ceased several years prior and any ridges would be worn down over the years. Perhaps box turtles have noticeable ridges for a longer period of their life as a result of how their shell grows over time (considerably more domed than a painted, yet hatchlings have the same general form). Also, there may be an adaptive advantage to painteds having less obvious ridges, as this would likely increase drag in a highly aquatic turtle. However, the aquatic nature may actually be the cause of the smoother shell, since there will inherently be more frictional forces acting on the shell.
Ryan
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