Combining in situ burrow casting and computed tomography scanning reveals burrow morphology and symbiotic associations in a burrow

Casting is one of the most effective methods for investigating the morphology of invertebrate burrows. However, this method is sometimes problematic, especially for studies of gravely sea floor habitats. This is because the cast often traps coarse-grained sediments (pebbles and shell fragments) on its surface, which interferes with investigation of the burrow morphology. In this study we used a combination of burrow casting and computed tomography (CT) scanning of a cast to determine the lumen morphology of the burrow of the strahlaxiid shrimp Neaxius acanthus (Decapoda: Axiidea) inhabiting a gravely intertidal flat in southwestern Japan. The images created using the CT data enabled us to accurately observe the morphology of the shrimp burrow, and to identify burrow associates including the galeommatoidean bivalve Barrimysia cumingii and the phenacolepadid gastropod Phenacolepas sp. The images also showed the position of the shrimp and its burrow associates within the burrow lumen. The combination of in situ burrow casting and CT scanning will aid the interpretation of the ecology of infauna in various seafloor settings.