Formation of Giant Spicule from Quartz Glass by the Deep Sea Sponge Monorhaphis

Abstract

The skeleton of the oldest multicellular animals, the spicules from siliceous sponges (the classes of Hexactinellida and Demospongiae), is composed of amorphous hydrated silica. The most outstanding feature of these spicules is that they are synthesized by the enzyme silicatein. After having studied the largest biosilica structures on earth, the up to 3 m long (diameter of 8.5 mm) spicules from the deep-sea hexactinellid Monorhaphis chuni, we describe that this silica material has the quality of quartz glass. Although such silica can be produced chemically only at high temperature and with aggressive chemicals, the animals fabricate this biomaterial physiologically and at low temperature (around 4 °C). These giant spicules are composed of almost pure silica. Likewise surprising is the fact that this biosilica contains a proteinaceous matrix, which is silicatein. Because these composite structured spicules also function as excellent light waveguides, our results may open new perspectives for the production of nanostructured materials and devices in the opto- and microelectronics industry.