More detailed discussion of the issues see more around the radical pair compass can be found in (Rogers & Hore, 2009; Mouritsen & Hore, 2012). What is crucial to this review is, Does it have a role in the navigational map? All the experiments described earlier involved

disrupting the magnetic compass, in no case was there an indication that the radical pair pathway is involved in map navigation. It does not appear that this mechanism detects intensity, nor indeed the polarity of the magnetic field, only inclination (Ritz et al., 2000). In theory, inclination could be used to detect latitude, so there is no reason why the radical pair mechanism could not be involved in the navigational map, but no experiment has tested this hypothesis. This may be due to the fact that it could be challenging to design an experiment that is able to disentangle

the use of the radical pair sense for a compass from Selleck Metformin its use in a map. Ferrimagnetic materials are those in which spontaneous magnetization occurs because the magnetic moments of atoms are opposed but unequal. This is seen in iron oxides, including the oldest known magnetic substance, magnetite. Ferrimagnetic material exists in a number of crystalline ‘domains’, including multi, single and supaparamagnetic. Multi domain magnetite has no magnetization, single domain has a permanent magnetic moment whereas superparamagnetic magnetite has a fluctuating magnetic moment, but it can be aligned to an external magnetic field (Kirschvink & Walker, 1985). Based on the discovery that bacteria containing single-domain magnetite passively align to the magnetic field (Blakemore, 1975), and that magnetite is a biogenic material that is widely present in the tissue of a diverse array of organisms, it was proposed that such material could form the basis of a magnetic sense in multicellular organisms

(Yorke, 1979; Kirschvink & Gould, 1981). To test this, it was proposed that the physical properties of the ferrimagnetic material could be used to predict the presence of magnetic material in sensory Baricitinib cells in the same way as it had been done in bacteria (Kirschvink, 1982). If ferrimagnetic material was involved in a sensory receptor that detected the Earth’s magnetic field, then a brief strong magnetic pulse that exceeded the coercivity (the magnetic force required to reduce the magnetization of the substance to zero) would re-magnetize the substance in the opposite direction if applied antiparallel to the original magnetization (Fig. 4). For most biogenic magnetite, the strength required to re-magnetize would be 0.1T, 5000 times the strength of the Earth’s magnetic field (Kirschvink & Walker, 1985; Kirschvink et al., 1985). If single-domain magnetite was present it would be re-magnetized, and if used by sensory cells, in theory, would lead to a change in the information the receptor gave.