Path followed:
- Is the fault in the components that perform any physical action?
Answer: Yes
- Is the fault in components that move?
Answer: Yes
- Is the fault in components that make the mechanism move?
Answer: Yes
- Is the faulty component designed to move the mechanism around?
Answer: Yes
- Is the faulty component needed for stability?
Answer: No
- Does the faulty component manipulate smaller objects?
Answer: Yes
- Is the faulty component rigid?
Answer: Yes
- Are there any external resources that can be used by the mechanism?
Answer: No
- Do the dimensions of the replaced component change after regeneration?
Answer: No
109) Rusty crayfish, Orconectes rusticus
Crayfish can be found in Canada and the United States in freshwater streams and lakes (Adams & Taylor). Crayfish have the ability of regenerating their claw or leg if it were to get amputated.
Soon after the limb as been amputated it undergoes a lag period in which the epithelial cells closest to the wound site proliferate and stretch to cover the wound (Hopkins). This creates a layer that encloses a blastema made from undifferentiated mesenchymal, epithelial, and endothelial cells. These cells begin to proliferate to accrue enough cells to regenerate the lost arm. Once there are enough the arm undergoes a basal growth phase (Durand; Hopkins). The mesenchyme cells begin to differentiate into muscles, tissues, and nerves of the newly regenerating arm (Durand). The epithelial cells are continually proliferating to allow the bud to grow and allow the arm to get bigger. The endothelial cells also help to reestablish blood vessels in the new leg. Once the leg has gotten big enough for the current skin it will undergo a molting cycle which removes the outer exoskeleton. This allows the crayfish to continue to grow with every successive molt by allowing water to infiltrate the newly generated exoskeleton and replace it with protein (Hopkins). Once the leg has been regenerated the blastema will disintegrate and the cells will stop proliferating. The crayfish may undergo more molts during his lifecycle but will only shed his exoskeleton which will be regenerated by epithelial cells.
Adams, S., Schuster, G.A. & Taylor, C.A. 2010. Orconectes rusticus. The IUCN Red List of Threatened Species. Version 2014.3. Web. 30 Dec. 2014.
http://www.iucnredlist.org/details/153835/0
Durand, James B. “Limb Regeneration and Endocrine Activity in the Crayfish.” The Biological Bulletin 118.2 (1960): 250-61. The Biological Bulletin. Web. 30 Dec. 2014.
http://www.biolbull.org/content/118/2/250.full.pdf+html
Hopkins, Penny M. “Limb Regeneration in the Fiddler Crab, Uca Pugilator: Hormonal and Growth Factor Control.”American Zoology 41.3 (2001): 389-98. Integrative & Comparative Biology. Web. 1 Jan. 2015.