Exploring annelid anatomy using micro-computed tomography: A taxonomic approach

The use of Micro-computed X-ray tomography (microCT or μCT) in the study of the anatomy of Annelids is becoming more common. Here we present a new approach to the anatomical study of six species (i.e. Phyllodoce lineata, Syllis garciai, Prionospio fallax, Branchiomma bombyx, Spirobranchus triqueter and Euclymene oerstedi) using μCT. These species represent several major annelid lineages and show therefore a wide range of morphological characteristics. Information obtained from μCT images of external and internal anatomy was compared with previous data with two major aims: 1) exploring whether quality of images allows accurate examination of annelid anatomy, and 2) evaluating the information provided by the different body characters, highlighting those with greater potential to be used for future biodiversity studies. Main conclusions obtained were: 1) the use of simple contrast staining or no staining at all provides good images that may be used in studies of comparative anatomy, 2) images of external anatomy show good definition only for macroscopic characters, 3) images of internal organs showed disparate results, being the digestive system the most promising structure, considering the quality of images and when assessing its regionalization and variability across taxa (genera, families).