The discovery of a novel silk production system in a marine amphipod provides insights into the wider potential of natural silks. The tube-building corophioid amphipod Crassicorophium bonellii produces from its legs fibrous, adhesive underwater threads that combine barnacle cement biology with aspects of spider silk thread extrusion spinning. We characterised the filamentous silk as a mixture of mucopolysaccharides and protein deriving from glands representing two distinct types. The carbohydrate and protein silk secretion is dominated by complex β-sheet structures and a high content of charged amino acid residues. The filamentous secretion product exits the gland through a pore near the tip of the secretory leg after having moved through a duct, which subdivides into several small ductules all terminating in a spindle-shaped chamber. This chamber communicates with the exterior and may be considered the silk reservoir and processing/mixing space, in which the silk is mechanically and potentially chemically altered and becomes fibrous. We assert that further study of this probably independently evolved, marine arthropod silk processing and secretion system can provide not only important insights into the more complex arachnid and insect silks but also into crustacean adhesion cements.
KeywordsMarine amphipod Crassicorophium bonellii Silk gland Extrusion spinning Barnacle Spider
We are grateful to D. Porter (University of Oxford) for discussions and to K. Halcrow (University of New Brunswick) for advice on the gland morphology. We thank D.A. Johnston (Biomedical Imaging Unit, University of Southampton) for confocal imaging and D. Lunn (University of Oxford) for help with the statistical analysis. The University of London Marine Biological Station (Millport) assisted with amphipod collection and access to SEM. V. Storch (Ruprecht-Karls University Heidelberg) kindly provided access to the TEM facility, while Stelzner Illustration helped with the scientific drawings. We are grateful for financial support provided by the European Research Council (grant SP2-GA-2008-233409) and the AFOSR (grant F49620-03-1-0111). To Skippy.
Conflict of Interest
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