This study was aimed at understanding the diet and the digestive function of the deep-living Lophogastrida species Lophogaster typicus (Mysidacea: Lophogastrida). Scanning electron microscopy (SEM) investigations have revealed that the mandibles exhibit typical features of a carnivorous diet, i.e. large and sharp incisor process and small molar one with only few scales. The analysis of gut contents confirms morphological data as crustacean remains have been recognized. However, the presence of a large quantity of unidentifiable soft particulate matter also indicates a saprophagous tendency. The external asymmetrical edge of the labrum consists of a small grinding area. The entire external face of the labrum exhibits numerous pores, which are related with glandular units. These units are organized into acini of two to four large cells. Two types of acini have been observed, i.e. with dark or clear cells. According to ultrastructural and cytochemical data, labral secretions are believed to be mucopolysaccharidic (for clear acini) and enzymatic components (for dark acini), and are therefore involved both in coating and in digesting the food. Moreover, presence of neuronal endings and endocrine cells, both associated with glandular units, and comparison between glandular units in starved and fed animals suggest a controlled release of the secretions. Therefore, the labrum plays a crucial role in the digestive function of the lophogastrid crustacean L. typicus, as it involves both mechanical and chemical breakdown of the food.