Investigating the locomotion of the sandfish in desert sand using NMR-Imaging

Abstract

The sandfish (Scincus scincus) is a lizard having the remarkable ability to move through desert sand for significant distances. It is well adapted to living in loose sand by virtue of a combination of morpological and behavioural specializations. We investigated the bodyform of the sandfish using 3D-laserscanning and explored its locomotion in loose desert sand using fast nuclear magnetic resonance (NMR) imaging. The sandfish exhibits an in-plane meandering motion with a frequency of about 3 Hz and an amplitude of about half its body lenght accompanied by swimming-like (or trotting) movements of its limbs. No torsion of the body was observed, a movement required for a digging-behavior. Simple calculations based on the Jassen model for granular material related to our findings on bodyform and locomotor behaviour render a local decompaction of the sand surrounding the moving sanfish very likely. Thus the sand locally behaves as a viscous fluid and not as a solid material. In this fluidised sand the sandfish is able to "swim" using its limbs. © 2008 Baumgartner et al.