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Bioelectromagnetism

 

 

 

 

Surprisingly, the ability of long-distance traveling animals, such as homing pigeons, migratory

birds, salmon, tuna, sea turtles, and whales, “not to get lost” seems to be related to this magnetic

sensor. Moreover, it has been experimentally reported that various animal species also use this

“magnetic sense” or “magnetoreception” (a sense which provides magnetic compass capabilities) to

move only a short distance (daily <~3 km). Tey can fgure out their “whereabouts” and “destination”

with the accuracy that they might have a GPS built in their bodies. Recently, a series of experiments

have tested how animals would respond when they were “virtually displaced” by exposing them to

the MF of a distant site. Some kinds of animals (see below) showed headings that compensated this

“virtual magnetic displacement,” thus indicating a large-scale magnetic map: eastern red-spotted

newts, Notophthalmus viridescens (Fischer et al., 2001), spiny lobsters, Panulirus argus (Boles and

Lohmann, 2003), green sea turtles, Chelonia mydas (K.J. Lohmann et al., 2004; Luschi et al., 2007),

lesser whitethroats, Sylvia curruca (Henshaw et al., 2010), Australian silvereyes, Zosterops lateralis

(Deutschlander et al., 2012), Eurasian reeds warblers, Acrocephalus scirpaceus (Chernetsov et al.,

2008, 2017; Kishkinev et al., 2013, 2015), and bonnethead sharks, Sphyrna tiburo (Keller et al., 2021). In

contrast, adult and juvenile European robins (Erithacus rubecula) and adult garden warblers (Sylvia

borin) under the same experimental conditions did not respond to this virtual magnetic displace­

ment, suggesting signifcant variation in how navigational maps are organized in diferent songbird

migrants (Chernetsov et al., 2020).

In addition, more recently, the following domestic or laboratory animal species that don’t migrate

for long distances can perceive and respond to the GMF: domestic dogs (Hart et al., 2013; Martini et al.,

2018; Benediktová et al., 2020; Yosef et al., 2020), cows and deer (Begall et al., 2008; Burda et al., 2009),

rodents (Mather and Baker, 1981; Malkemper et al., 2015, Norimoto and Ikegaya, 2015), domestic chick­

ens (Freire et al., 2005, 2008; Wiltschko et al., 2007; Denzau et al., 2013a,b), zebra fnch (Voss et al., 2007;

Pinzon-Rodriguez and Muheim, 2017), zebrafsh (Skauli et al., 2000; Sherbakov et al., 2005; Takebe

et al., 2012; Osipova et al., 2016), carp (Hart et al., 2012), and domestic insects such as cockroaches

(Vácha, 2006; Vácha et al., 2008, 2009; Bazalova et al., 2016; Slaby et al., 2018), fruit fies (Dommer et al.,

2008; Gegear et al., 2008, 2010; Yoshii et al., 2009; Fedele et al., 2014a,b; Marley et al., 2014; Bae et al., 2016;

Qin et al., 2016; Lee et al., 2018; Oh et al., 2020; Bradlaugh et al., 2021), and nematodes, Caenorhabditis

elegans (Wu and Dickman, 2012; Vidal-Gadea et al., 2015; Clites and Pierce, 2017).

Moreover, it has been demonstrated that mole rats also have magnetoreception, and they use the

MF azimuth to determine compass heading (frst described by Burda et al., 1990). Surprisingly, it is

suggested that mole rats perceive MFs with their minute eyes, probably relying on magnetite-based

receptors in the cornea (Caspar et al., 2020). Tus, in addition to migratory animals, recently it has been

reported that many non-migratory animals possess magnetoreception, and therefore, it is conceivable

that magnetoreception is one of the senses that many animal species have.

Magnetic alignment, the preference to align the body axis in a certain angle relative to the GMF lines,

is expressed by a variety of vertebrates during diverse behaviors, ofen during grazing and resting, and

is regarded as a clear indicator of magnetoreceptive abilities (Begall et al., 2013). In the case of domestic

dogs’ sensitivity to MFs, Hart et al. (2013) found that dogs during defecation and urination preferred

to excrete with the body being aligned along the N-S axis under calm GMF conditions. Tis direc­

tional behavior was abolished under unstable GMF (Hart et al., 2013). Te best predictor of the behav­

ioral switch was the rate of change in declination, i.e., the polar orientation of the GMF (Hart et al.,

2013). Tis declination compass was also observed in American cockroaches, Periplaneta americana

(Bazalova et al., 2016), fruit fies, Drosophila melanogaster (Lee et al., 2018), and Eurasian reed warblers,

Acrocephalus scirpaceus (Chernetsov et al., 2017).

Oberbauer et al. (2021) performed a similar study using methodology analogous to that in the origi­

nal paper by Hart et al. (2013). However, Oberbauer et al. (2021) did not detect any preference for body

alignment during defecation and urination, although they utilized a greater number of dogs, collected

the data within a brief time window making the data very comparable, and had a more balanced rep­

resentation of individual dogs when compared to the previous study by Hart et al. (2013). Tus, their