1. Is the fault in the components that perform any physical action?
Answer: No
2. Is the faulty component part of the mechanism’s body?
Answer: Yes
3. Is the faulty component in the structure of the mechanism?
Answer: No
4. Does the damaged component provide protection?
Answer: Yes
5. Is the component serve any other purpose than protection?
Answer: No
6. Can the adaptation occur at any time after failure?
Answer: No
18) Painted turtle, Chrysemys picta
Painted turtles can be found in Canada, United States and Mexico (Van Dijk). These turtles live near rivers or marshes that are shallow but full of vegetation. Painted turtles have the ability of regenerating the scutes on their shells to allow for growth and to replace damaged shell sections.
At the end of the growing season keratinocytes directly beneath the old scute layer produce thin alpha-keratin cells that form a scission layer beneath the old stratum corneum (Alibardi). During the winter season the cells remain in the germinative layer of the carapace and plastron (Alibardi). The next spring new beta-keratin cells are produced beneath the scission layer. The epidermis under the scutes produces thymidine and histidine, while the corneous layer under the scission layer produces lipids, which forms the new layer of scute and help the old scute flake off (Alibardi). So as long as the site where the shell was injured can still produce keratinocytes a new piece of shell will be able to generate and replace the damaged portion.
Van Dijk, P.P. Chrysemys picta. The IUCN Red List of Threatened Species. Version 2014.3, 2013. Web. 27 Nov. 2014.
http://www.iucnredlist.org/details/163467/0
Alibardi, L. “Proliferation in the Epidermis of Chelonians and Growth of the Horny Scutes.” Journal of Morphology 265.1 (2005): 52-69. NCBI. Web. 25 Nov. 2014.
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