Causes of Structure Degradation
editThe overall structure of the limpet teeth is relatively stable within most natural conditions given the limpet’s ability to produce new teeth at a similar rate to the degradation. [1] Individual teeth are subjected to shear stresses as the tooth is dragged along the rock. Goethite as a mineral is a relatively soft iron based material [2] which increases the chance of physical damage to the structure. Limpet teeth and the radula have also been shown to experience greater levels of damage in CO2 acidified water.
Crystal Structure:
editGoethite crystals form in at the start of the tooth production cycle and remain as a fundamental part of the tooth with intercrystal space filled with amorphous silica. Existing in multiple morphologies, “Prisms with rhomb-shaped sections are the most frequent...”. [3] The goethite crystals are stable and well formed for a biogenic crystal. The transport of the mineral to create the crystal structures has been suggested to be a dissolution-reprecipitation mechanism as of 2011. Limpet tooth structure is dependent upon living depth of the specimen. While deep water limpets have been shown to have the same elemental composition as shallow water limpets, deep water limpets do not show crystalline phases of goethite. [4]
Characterizing Composition:
edit
The most prominent metal by percent composition is iron in the form of goethite. Goethite has the chemical formula of FeO(OH) and belongs to a group known as oxy-hydroxides. As mentioned in INSERT, there exists amorphous silica between the goethite crystals. Surrounding the goethite is a matrix of chitin. Chitin has a chemical formula of C8H13O5N. Other metals have been shown to be present with the relative percent compositions varying on geographic locations. The goethite has been reported to have a volume fraction of approximately 80%. [7].
Regional dependency:
editLimpets from different locations were shown to have different elemental ratios within their teeth and teeth. Iron is consistently most abundant however other metals such as sodium, potassium, calcium, and copper were all shown to be present to varying degrees. [8] The relative percentages of the elements have also been shown to differ from one geographic location to another. This demonstrates an environmental dependency of some kind; however the specific variables are currently undetermined. [9]
Notes
edit- ^ Shaw, Jeremy; Macey, David; Brooker, Lesley; Clode, Peta. "Gale - Enter Product Login". go.galegroup.com. University of Chicago Press.
- ^ Chicot, D.; Mendoza, J.; Zaoui, A.; Louis, G.; Lepingle, V.; Roudet, F.; Lesage, J. (October 2011). "Mechanical properties of magnetite (Fe3O4), hematite (α-Fe2O3) and goethite (α-FeO·OH) by instrumented indentation and molecular dynamics analysis". Materials Chemistry and Physics. 129 (3): 862–870. doi:10.1016/j.matchemphys.2011.05.056.
- ^ Weiner, Steve; Addadi, Lia (4 August 2011). "Crystallization Pathways in Biomineralization". Annual Review of Materials Research. 41 (1): 21–40. doi:10.1146/annurev-matsci-062910-095803.
- ^ Cruz, R.; Farina, M. (4 March 2005). "Mineralization of major lateral teeth in the radula of a deep-sea hydrothermal vent limpet (Gastropoda:Neolepetopsidae)". Marine Biology. 147 (1): 163–168. doi:10.1007/s00227-004-1536-y.
- ^ Sone, Eli D.; Weiner, Steve; Addadi, Lia (2007-06-01). "Biomineralization of limpet teeth: A cryo-TEM study of the organic matrix and the onset of mineral deposition". Journal of Structural Biology. 158 (3): 428–444. doi:10.1016/j.jsb.2007.01.001.
- ^ Sone, Eli D.; Weiner, Steve; Addadi, Lia. "Morphology of Goethite Crystals in Developing Limpet Teeth: Assessing Biological Control over Mineral Formation†". Crystal Growth & Design. 5 (6): 2131–2138. doi:10.1021/cg050171l.
- ^ Barber, Asa H.; Lu, Dun; Pugno, Nicola M. (6 April 2015). "Extreme strength observed in limpet teeth". Journal of The Royal Society Interface. p. 20141326. doi:10.1098/rsif.2014.1326.
- ^ Davies, Mark S.; Proudlock, Donna J.; Mistry, A. (May 2005). "Metal Concentrations in the Radula of the Common Limpet, Patella vulgata L., from 10 Sites in the UK". Ecotoxicology. 14 (4): 465–475. doi:10.1007/s10646-004-1351-8.
- ^ Cruz, R.; Farina, M. (4 March 2005). "Mineralization of major lateral teeth in the radula of a deep-sea hydrothermal vent limpet (Gastropoda:Neolepetopsidae)". Marine Biology. 147 (1): 163–168. doi:10.1007/s00227-004-1536-y.