Letters to Nature

Nature 421, 841-843 (20 February 2003) | doi:10.1038/nature01416; Received 29 August 2002; Accepted 24 December 2002

Architecture and material properties of diatom shells provide effective mechanical protection

Christian E. Hamm1, Rudolf Merkel2,3, Olaf Springer4, Piotr Jurkojc4, Christian Maier2, Kathrin Prechtel2 & Victor Smetacek1

  1. Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
  2. Technische Universität München, Physics Department (Biophysics Group E22), 85748 Garching, Germany
  3. Research Centre Jülich, Institute of Thin Films and Interfaces, 52425 Jülich, Germany
  4. Hochschule Bremen – University of Applied Science, Neustadtswall 30, 28199 Bremen, Germany

Correspondence to: Christian E. Hamm1 Correspondence and requests for materials should be addressed to C.E.H. (e-mail: Email: chamm@awi-bremerhaven.de).

Diatoms are the major contributors to phytoplankton blooms in lakes and in the sea and hence are central in aquatic ecosystems and the global carbon cycle1. All free-living diatoms differ from other phytoplankton groups in having silicified cell walls in the form of two 'shells' (the frustule) of manifold shape and intricate architecture2 whose function and role, if any, in contributing to the evolutionary success of diatoms is under debate3, 4, 5. We explored the defence potential of the frustules as armour against predators by measuring their strength. Real and virtual loading tests (using calibrated glass microneedles and finite element analysis) were performed on centric and pennate diatom cells. Here we show that the frustules are remarkably strong by virtue of their architecture and the material properties of the diatom silica. We conclude that diatom frustules have evolved as mechanical protection for the cells because exceptional force is required to break them. The evolutionary arms race between diatoms and their specialized predators will have had considerable influence in structuring pelagic food webs and biogeochemical cycles.