Surface architecture of the mouth cavity of a carnivorous fish Rita rita (Hamilton, 1822) (Siluriformes, Bagridae)

The topological characteristics of the mouth cavity of the carnivorous fish Rita rita were explored by means of scanning electron microscopy. The mouth cavity lining of R. rita may be distinguished into the roof and the floor. Papilliform teeth present on the premaxillae and the anterior regions of the dentaries are associated with seizing, grasping and holding of prey. The molariform teeth on the palatine regions and the dentaries are used for crushing and grinding of food items. The taste buds in the mouth cavity are of three types (types 1, 11, and 111). The different types of taste buds are elevated from the epithelium at different levels, which may be useful for ensuring full utilization of the gustatory ability of the fish, detection and analysing of taste substances, as well as for assessing the quality and palatability of food, during its retention in the mouth cavity. A firm consistency or rigidity of the free surface of the epithelial cells may be attributed to compactly arranged microridges. These structures protect against physical abrasions potentially caused during food manoeuvring and swallowing. Furthermore, protection of the epithelium from abrasion is enhanced with mucous cell secretions, which lubricate ingested food items. Observations of the surface architecture of the mouth cavity of R. rita are discussed within the context of feeding and habitat preferences as well as ecomorphological adaptation of the species.