The Evolution of Advanced Mechanical Defenses and Potential Technological Applications of Diatom Shells
Abstract:Diatoms are unicellular algae with silicified cell walls, which exhibit a high degree of symmetry and complexity. Their diversity is extraordinarily high; estimates suggest that about 10 5 marine and limnic species may exist. Recently, it was shown that diatom frustules are mechanically resilient, statically sophisticated structures made of a tough glass-like composite. Consequently, to break the frustules, predators have to generate large forces and invest large amounts of energy. In addi- tion, they need feeding tools (e. g., mandibles or gastric mills) which are hard, tough, and resilient enough to resist high stress and wear, which are bound to occur when they feed on biomineral- ized objects such as diatoms or other biomineralized protists. Indeed, many copepods feeding on diatoms possess, in analogy to the enamelcoated teeth of mammals, amazingly complex, silica- laced mandibles. The highly developed adaptations both to protect and to break diatoms indicate that selection pressure is high to optimize material properties and the geometry of the shells to achieve mechanical strength of the overall structure. This paper discusses the mechanical challenges which force the development of mechanical defenses, and the structural components of the diatom frustules which indicate that evolutionary optimization has led to mechanically sophisticated structures. Understanding the diatom frustule from the nanometer scale up to the whole shell will provide new insights to advanced combinations of nanostructured composite ceramic materials and lightweight architecture for technological applications.
Document Type: Research Article
Publication date: January 1, 2005
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- Journal for Nanoscience and Nanotechnology (JNN) is an international and multidisciplinary peer-reviewed journal with a wide-ranging coverage, consolidating research activities in all areas of nanoscience and nanotechnology into a single and unique reference source. JNN is the first cross-disciplinary journal to publish original full research articles, rapid communications of important new scientific and technological findings, timely state-of-the-art reviews with author's photo and short biography, and current research news encompassing the fundamental and applied research in all disciplines of science, engineering and medicine.
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