TY - JOUR

T1 - Magnetite biomineralisaton in termites.

AU - Maher, Barbara A.

PY - 1998/4/22

Y1 - 1998/4/22

N2 - Experimental evidence exists for magnetoreception in termites, a major component of the soil macrofauna in many tropical countries. This preliminary study identifies for the first time the presence of biogenic ferrimagnets (magnetite?) in two species of termite (Nasutitermes exitiosus and Amitermes meridionalis), based on magnetic measurements of whole termite specimens and individual body sections, and analysis by electron microscopy of magnetically-extracted grains. The magnetic measurements indicate the presence of very small concentrations of magnetic material, with more magnetic grains in the thorax/abdomen region compared to the head. Magnetic interaction, due to clustering of grains, is also identified by the measurements. Analysis of magnetic extracts by transmission electron microscopy identifies the presence of uniquely ultrafine (10nm) and unidimensional grains of ferrimagnetic material, unequivocally distinct from any possible extraneous magnetite sources, such as ingested soil. Hence, this provides firm evidence for biogenic formation of this magnetic material by these two termite species. Such ultrafine grains would be superparamagnetic, ie. incapable of carrying a permanent magnetic moment, unless they were sited in clusters of interacting grains, when some remanence-carrying ability - and hence magnetotaxis - would be possible.

AB - Experimental evidence exists for magnetoreception in termites, a major component of the soil macrofauna in many tropical countries. This preliminary study identifies for the first time the presence of biogenic ferrimagnets (magnetite?) in two species of termite (Nasutitermes exitiosus and Amitermes meridionalis), based on magnetic measurements of whole termite specimens and individual body sections, and analysis by electron microscopy of magnetically-extracted grains. The magnetic measurements indicate the presence of very small concentrations of magnetic material, with more magnetic grains in the thorax/abdomen region compared to the head. Magnetic interaction, due to clustering of grains, is also identified by the measurements. Analysis of magnetic extracts by transmission electron microscopy identifies the presence of uniquely ultrafine (10nm) and unidimensional grains of ferrimagnetic material, unequivocally distinct from any possible extraneous magnetite sources, such as ingested soil. Hence, this provides firm evidence for biogenic formation of this magnetic material by these two termite species. Such ultrafine grains would be superparamagnetic, ie. incapable of carrying a permanent magnetic moment, unless they were sited in clusters of interacting grains, when some remanence-carrying ability - and hence magnetotaxis - would be possible.

KW - termites

KW - biogenic magnetite

KW - biomineralisation

KW - magnetotaxis

KW - magnetoreception

U2 - 10.1098/rspb.1998.0354

DO - 10.1098/rspb.1998.0354

M3 - Journal article

VL - 265

SP - 733

EP - 737

JO - Proceedings of the Royal Society B: Biological Sciences

JF - Proceedings of the Royal Society B: Biological Sciences

SN - 0962-8452

IS - 1397

ER -