How does an animal with no limbs dig its way through compact soil? In this study recently published in Journal of Zoology, the authors used for the first time X-ray emission to film excavation behaviour and performance of amphisbaenids, burrowing legless reptiles that are able to dig permanent underground galleries in heavily compacted soils. Amphisbaenids have specific adaptations to fossorial locomotion: their skin is only loosely connected to their body so that the trunk can move backwards and forwards inside the skin, and their skulls are strongly ossified and compacted, and can be shaped like a shovel or a spade.
As supplementary material to their paper, the authors provided a video (available here) of the forwards and backwards locomotion of an amphisbaenid within a substrate. Using videofluoroscopy, the authors were also able to describe for the first time the unique backwards movement of amphisbaenids in their tunnels. As can be seen on the video, during the backwards movement the vertebral column of the animal moves independently from the skin, forming ‘waves’ inside its body. This new technology will enable further investigations and analyses of the fossorial locomotion of these unique animals.