Hardness in arthropod exoskeletons in the absence of transition metals
Received 3 September 2009; received in revised form 27 January 2010; accepted 3 February 2010. published online 11 February 2010.
Abstract
The arthropod cuticle is a remarkable and versatile biological material commonly composed of chitin and proteins. Lessons can be learned from the way it is adapted to fit its functions. The larval jewel beetle, Pseudotaenia frenchi, demonstrates hardness in the cutting edge of the mandibles in excess of the mineralized carapace of stone crabs and compares favourably with some stainless steels. Yet this is a form of cuticle which is devoid of transition metals or mineralization. In seeming contradiction, the similarly dark coloured adult beetle mandibles contain the transition metal manganese, but are significantly softer. Energy dispersive X-ray analysis and infrared spectroscopy have been used to investigate the differences in composition of mandible cuticle of the adult and larval beetles.
aCentre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, Qld 4072, Australia
bSchool of Biological Sciences, The University of Queensland, St. Lucia, Qld 4072, Australia
cSchool of Mechanical and Mining Engineering, The University of Queensland, St. Lucia, Qld 4072, Australia
dSchool of Physical and Chemical Sciences, Queensland University of Technology, 2 George Street, Brisbane, Qld 4000, Australia
eAustralian Insect Farm, PO Box 26, Innisfail, Qld 4860, Australia
Corresponding author. Address: Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, Qld 4072, Australia. Tel.: +61 7 3365 7086; fax: +61 7 3346 3993.
ABSTRACT