A new preparation technique of daphnids for Scanning Electron Microscopy using hexamethyldisilazane

SEM requires special preparation techniques to avoid artifacts, especially in aquatic organisms. Not all organisms can be prepared equally well for SEM. For example in Daphnia, preparation causes major shrinkage of the carapace in most species. We present a new preparation technique for Daphnia using hexamethyldisilazane (HMDS), which avoids these problems. We compared this method with the common critical point drying technique (CPD). The routinely used CPD caused shrinkage in the daphnids, predominantly in the region of the neck and the brood chamber. In contrast, all rested Daphnia species immersed in hexamethyldisilazane (HMDS) and dried slowly overnight in a vacuum desiccator revealed an excellent surface. The good results, low costs and easy operation without the requirement of special equipment favor HMDS as drying agent for SEM investigations in daphnids.