Use of a magnetic compass for Y-axis orientation in premetamorphic newts (Triturus boscai)

Abstract

Experiments were carried out to investigate whether premetamorphic larvae of Bosca's newt (Triturus boscai) are capable of using the geomagnetic field for Y-axis orientation (i.e., orientation toward and away from shore). Larvae were trained outdoor in two different training configurations, using one training tank aligned along the magnetic north-south axis, with shore facing north, and another training tank positioned with its length along the east-west axis, with shore located west. After training, premetamorphic newts were tested in an outdoor circular arena surrounded by a pair of orthogonally aligned cube-surface coils used to alter the alignment of the Earth's magnetic field. Each newt was tested only once, in one of four magnetic field alignments: ambient magnetic field (i.e., magnetic north at North), and three altered fields (magnetic north rotated to East, West, South). Distributions of magnetic bearings from tested larvae indicated that they oriented bimodally along the magnetic direction of the trained Yaxis. These findings demonstrate that T. boscai larvae are sensitive to the geomagnetic field and can use it for orienting along a learned Y-axis. This study is the first to provide evidence of Y-axis orientation, accomplished by a magnetic compass, in larval urodeles.

Magnetic Compass Orientation in Larval Iberian Green Frogs, Pelophylax Perezi

“…Bimodal y‐axis magnetic compass orientation has also been observed in amphibian urodeles (eastern red‐spotted newts, N. viridescens : Deutschlander et al. 2000; Bosca's newts, L. boscai : Rodríguez‐García & Diego‐Rasilla 2006) and anurans (bullfrogs, R. catesbeiana : Freake et al. 2002; Freake & Phillips 2005), and it has been suggested that variation in training/testing protocol, and in individual animal motivation, may produce either unimodal or bimodal orientation relative to the y‐axis (Freake et al.…”

“…2002; Diego‐Rasilla et al. 2005; Freake & Phillips 2005; Rodríguez‐García & Diego‐Rasilla 2006) indicate that sensitivity to the alignment of the magnetic field is a widespread sensory capability not only among urodele, but also among anuran, amphibians.…”

“…2000) and, more recently, in alpine newts, Mesotriton alpestris (Diego‐Rasilla 2003; Diego‐Rasilla et al. 2005) and Bosca's newts, Lissotriton helveticus (Rodríguez‐García & Diego‐Rasilla 2006). The Eastern newt's magnetic compass is light dependent (Phillips & Borland 1992a,b; Deutschlander et al.…”

“…Magnetic compass orientation has been demonstrated in a wide variety of animals (Wiltschko & Wiltschko 1995;Diego-Rasilla 2004;Wiltschko & Wiltschko 2005). Among urodele amphibians, use of directional information derived from the earth's magnetic field has been demonstrated in the cave salamander, Eurycea lucifuga (Phillips 1977), Eastern red-spotted newts, Notophthalmus viridescens (Phillips 1986a(Phillips ,b, 1987Phillips & Borland 1994;Phillips et al 1995;Deutschlander et al 2000) and, more recently, in alpine newts, Mesotriton alpestris (Diego-Rasilla 2003;Diego-Rasilla et al 2005) and Bosca's newts, Lissotriton helveticus (Rodríguez-García & Diego-Rasilla 2006). The Eastern newt's magnetic compass is light dependent (Phillips & Borland 1992a,b;Deutschlander et al 1999;Phillips et al 2001) and experimental evidence is consistent with a mechanism of magnetoreception involving a photo-induced biochemical reaction that forms radical pair intermediates (i.e.…”

Evidence of light-dependent magnetic compass orientation in urodele amphibian larvae

“…However, evidence for y-axis magnetic compass orientation among adult amphibians has only been reported in Eastern red-spotted newts, Notophthalmus viridescens (Phillips, 1986a,b), while among larval amphibians it has been reported for three species of frogs (Lithobates catesbeianus, Pelophylax perezi and Rana temporaria (Diego-Rasilla et al, 2013;Diego-Rasilla and Phillips, 2007;Freake et al, 2002), and one species of urodele, Lissotriton boscai (Rodríguez-García and Diego-Rasilla, 2006).…”