| Affiliation: | 1. Institute of Bioanalytical Chemistry, Dresden University of Technology, Bergstr. 66, D‐01069 Dresden, Germany;2. Max Planck Institute of Chemical Physics of Solids, Noetnitzer Str. 40, D‐01187 Dresden, Germany;3. Institute of Chemistry and Applied Ecology, Far Eastern National University, Sukhanova 8, 690650 Vladivostok, Russia;4. Leeds Museum Discovery Centre, Carlisle Road,1, Leeds LS10 1LB, UK;5. P.P. Shirshov Institute of Oceanology RAS, Nahimovski Prospect 36, 117312 Moscow, Russia;6. MBZ and Institute of Materials Science, Dresden University of Technology, Budapester Str. 27, D‐01069 Dresden, Germany;7. Institute of Solid State Physics, Dresden University of Technology, Zellescher Weg 16, D‐01069, Dresden, Germany;8. European XFEL GmbH, Notkestr. 85, D‐22607 Hamburg, Germany;9. Centre “Bioengineering” RAS, 7/1, Prospekt 60‐ya Oktiabrya, 117312 Moscow, Russia;10. Functional Morphology and Biomechanics, Zoological Institute, Christian‐Albrecht‐Universitaet zu Kiel, Am Botanischen Garten 9, D‐24098 Kiel, Germany;11. Department of Chemical Engineering, University of Patras, 1, Stadiou Str., GR‐265 04 Patras, Greece;12. Friday Harbor Laboratories, University of Washington, 620 University Road, Friday Harbor, WA. 98250, USA |
| Abstract: | The hierarchically structured glass sponge Caulophacus species uses the first known example of a silica and calcite biocomposite to join the spicules of its skeleton together. In the stalk and body skeleton of this poorly known deep‐sea glass sponge siliceous spicules are modified by the addition of conical calcite seeds, which then form the basis for further silica secretion to form a spinose region. Spinose regions on adjacent spicules are then joined by siliceous crosslinks, leading to unusually strong cross‐spicule linkages. In addition to the biomaterials implications it is now clear, from this first record of a biomineral other than silica, that the hexactinellid sponges are capable of synthesizing calcite, the ancestral skeletal material. We propose that, while the low concentrations of calcium in deep sea waters drove the evolution of silica skeletons, the brittleness of silica has led to retention of the more resilient calcite in very low concentrations at the skeletal joints. |
