Ferreira de Oliveira, Jandira; Wajnberg, Eliane; Motta de Souza Esquivel, Darci; Weinkauf, Sevil; Winklhofer, Michael; Hanzlik, Marianne
Ant antennae: are they sites for magnetoreception?
In: Journal of the Royal Society Interface, Vol. 7, No. 42: pp. 143-152
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Migration of the Pachycondyla marginata ant is significantly oriented at138 with respect to the geomagnetic north-south axis. On the basis ofprevious magnetic measurements of individual parts of the body(antennae, head, thorax and abdomen), the antennae were suggested tohost a magnetoreceptor. In order to identify Fe(3+)/Fe(2+) sites inantennae tissue, we used light microscopy on Prussian/Turnbull’sblue-stained tissue. Further analysis using transmission electronmicroscopy imaging and diffraction, combined with elemental analysis,revealed the presence of ultra-fine-grained crystals (20-100 nm) ofmagnetite/maghaemite (Fe(3)O(4)/gamma-Fe(2)O(3)), haematite(alpha-Fe(2)O(3)), goethite (alpha-FeOOH) besides (alumo)silicates andFe/Ti/O compounds in different parts of the antennae, that is, in thejoints between the third segment/pedicel, pedicel/scape and scape/head,respectively. The presence of (alumo)silicates and Fe/Ti/O compoundssuggests that most, if not all, of the minerals in the tissue areincorporated soil particles rather than biomineralized by the ants.However, as the particles were observed within the tissue, they do notrepresent contamination. The amount of magnetic material associated withJohnston’s organ and other joints appears to be sufficient to produce amagnetic-field-modulated mechanosensory output, which may thereforeunderlie the magnetic sense of the migratory ant.