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: Yes
4. Does the fault appear in components that provide rigidity to the mechanism?
Answer: No
5. Is the faulty component responsible for supporting other components?
Answer: Yes
6. Is the fault in critical components of the mechanism?
Answer: Yes
7. Does the faulty component control other parts of the mechanism?
Answer: Yes
8. Are there several internal resources that can be used by the mechanism?
Answer: Yes
9. Are there any external resources that can be used by the mechanism?
Answer: No
86) Laver spire snail, Hydrobia ulvae
Laver spire snails can be found off the coasts of Britain and northwest Europe (ÒLavire Spire ShellÓ). These snails are good at gluing the sand and mud together on the ocean floor with their droppings. Laver spire snails have the ability of regenerating their head after decapitation.
Soon after the snail was decapitated the body wall muscle contracted to bring the two wound edges together and seal the wound. Once the walls were close enough the epithelial cells near the edges would proliferate and form the skin over the wound. This layer would also swell which were essentially blastemas. Some of the bulges would use the undifferentiated cells of the epithelium to proliferate and differentiate into small stick buds that would later form the tentacles (Gorbushin et al.). Other bulges appeared to get invaginations which would create the eyes. Then other undifferentiated cells not in the bulges would differentiate and form the proboscis, nose, of the snail (Gorbushin et al.). Another bud would form ventral to the wound scar and proliferate and differentiate cells into the propodium (Gorbushin et al.). Next black pigment would appear in the eye invaginations and other epithelial cells were forming the buccal complex and buccal ganglia could be found (Gorbushin et al.). Finally the unpigmented bodies of the skin gradually became pigmented. Once all of the structures of the head had been formed from proliferation and differentiation the epithelium would stop producing cells used for regeneration.
“Laver Spire Shell.” Laver Spire Shell Videos, Photos, and Data. Wildscreen Arkive, 2014. Web. 20 Dec. 2014.
http://www.arkive.org/laver-spire-shell/hydrobia-ulvae/
Gorbushin, Alexander M., Ivan A. Levakin, Nadejda A. Panchina, and Yuri V. Panchin. “HYDROBIA ULVAE (GASTROPODA: PROSOBRANCHIA): A NEW MODEL FOR REGENERATION STUDIES.” The Journal of Experimental Biology 204 (2001): 283-89. The Journal of Experimental Biology. Web. 20 Dec. 2014.
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