Evidence for the use of reflected self-generated seismic waves for spatial orientation in a blind subterranean mammal

Abstract

Erratum Kimchi, T., Reshef, M. and Terkel, J. (2005). Evidence for the use of reflected self-generated seismic waves for spatial orientation in a blind subterranean mammal. J. Exp. Biol. 208,[647][648][649][650][651][652][653][654][655][656][657][658][659] In the first on-line version of this paper, published on 4 January 2005, an incorrect version of Fig. 5 was published. The error has been rectified and the current on-line version and print versions of the figure are correct.In addition, in the first on-line version of the paper, Fig. 1 was published in black and white instead of in colour. This has also been rectified in the current on-line version and the print version is correct. 647The blind mole-rat is a solitary subterranean rodent that digs and inhabits its own branching tunnel system, which it does not leave unless forced to (e.g. if water floods its tunnels). In nature the mole-rat encounters different types of obstacles that block and disconnect sections of its tunnel. In a recent field study using various open ditches and wood or stone obstacles we found that mole-rats are able to detect the presence of obstacles blocking their tunnel path and burrow a highly efficient detour to accurately rejoin the two disconnected parts of the tunnel. The mole-rats used two different bypass strategies, depending on the size of the ditch encountered: a bypass around short ditches, or a bypass under long (over 300·cm length) ditches (Kimchi and Terkel, 2003a). The physical properties of the encountered obstacles affected the burrowing distance from the obstacle edge: (a) for open ditches, a side bypass 10-20·cm from the obstacle boundaries; or (b) for wood or stone obstacles, a side bypass 3-8·cm from the obstacle boundaries. When the obstacle was placed asymmetrically across the tunnel, the mole-rats always burrowed their bypass around the shorter side, while they showed no preference for a particular side in symmetrically placed ditches (Kimchi and Terkel, 2003b). These findings demonstrated the mole-rat's ability to estimate the size and shape of the obstacle, its own exact position relative to the obstacle boundaries and even the obstacle's density, through the soil medium. Subterranean mammals like the blind mole-rat (Rodentia: Spalax ehrenbergi) are functionally blind and possess poor auditory sensitivity, limited to low-frequency sounds. Nevertheless, the mole-rat demonstrates extremely efficient ability to orient spatially. A previous field study has revealed that the mole-rat can assess the location, size and density of an underground obstacle, and accordingly excavates the most efficient bypass tunnel to detour around the obstacles. In the present study we used a multidisciplinary approach to examine the possibility that the mole-rat estimates the location and physical properties of underground obstacles using reflected self-generated seismic waves (seismic 'echolocation').Our field observations revealed that all the monitored mole-rats produced low-frequency seismic waves (250-300·Hz) at intervals of 8±5...

Measuring airborne components of seismic body vibrations in a Middle-Asian sand-dwelling Insectivora species, the piebald shrew (Diplomesodon pulchellum)

“…It is probable that these hair ridges enable detection of some kind of reflected vibration from the sand below, similar to the seismic exploration reported for mole-rats (Kimchi et al, 2005). For insectivores, the somatosensory detection of ground vibrations via the forepaws has also been proposed for star-nosed moles, Condylura cristata, as forepaws are hugely represented in the somatosensory cortex, suggesting that the forepaws provide an important sensory surface (Catania and Kaas, 1995).…”

“…mammals that generate seismic vibrations with parts of their body (Randall, 2001;Kimchi et al, 2005), piebald shrews apparently generate vibrations with their body-wall muscles. In the piebald shrews in this study, vibrations occurred in bouts, and the frequency of the airborne component of vibration was about 160Hz.…”

“…Airborne components of seismic vibration have been investigated in some insects (Hill, 2009) and in mole rats (Kimchi et al, 2005). However, the acoustic recording of the vibratory drumming is an innovation of the current study.…”

Magnetic compass orientation in C57BL/6J mice

“…The precision with which the mice in the present study positioned their nests (especially the mice trained along the N-S axis) indicates that the magnetic compass provides an accurate source of directional information that is likely to be useful in a variety of behavioral contexts. Future studies are needed to determine whether mice use magnetic compass cues in other forms of directional orientation (e.g., maze learning and path integration, as suggested by a recent study of mole rats; Kimchi, Reshef, & Terkel, 2005).…”

Biosonar-Inspired Source Localization in Low SNR

“…It has been recently discovered ( Kimchi et al, 2005) that the blind mole rat uses sonar-like exploration of the underground. This rat, which lives underground and has no functioning eyes, generates ground stimulation by banging its head on the wall of its tunnels.…”