Deciduous teeth first teeth seen in the mouth are the mandibular centrals and the last are the maxillary second molars. The primary teeth are made up of central incisors, lateral incisors, canines, first molars, and secondary molars; there is one in each quadrant, making a total of four of each tooth. All of these are gradually replaced with a permanent counterpart except for the primary first and second molars; they are replaced by premolars. The replacement of primary teeth begins around age six, when the permanent teeth start to appear in the mouth, resulting in mixed dentition. The erupting permanent teeth cause
Pharyngeal teeth new species of "Meiopriapulus", a marine worm in the Priapulida, bears pharyngeal teeth. Fossils of the "Yunnanozoon" and "Haikouella" possess pharyngeal teeth. The lower pharyngeal bones of cichlids also carry specialized teeth which augment their normal mandibular teeth in the breakdown of food. Pharyngeal teeth Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species otherwise lacking teeth. Many popular aquarium fish such as goldfish and loaches have these structures. Members of the genus "Botia" such as clown loaches are known to make distinctive clicking sounds when they grind