Freshwater Fishes of Texas: A Field Guide

Appendix: Counting Pharyngeal Teeth

Appendix Counting Pharyngeal Teeth Pharyngeal teeth appear as toothlike projections protruding from the fifth pair of bony gill arches (also termed pharyngeal arches) embedded just posterior to the gill-bearing arches. Pharyngeal arch Each arch will typically have one or two rows of teeth or, in the case of the common carp (Cyprinus carpio), three rows. The function of these teeth varies among species, from holding prey in the mouth to ripping, mashing, or grinding food items. The shape of the teeth usually gives an indication of their purpose (e.g., clawlike teeth are for ripping and tearing; molarlike teeth are for mashing and grinding). Counts of pharyngeal teeth can serve as a means of identifying some fishes of the family Cyprinidae. The formula for counting these teeth is as follows: count from the left arch, with the inner row (or lesser row) being counted first, followed by the outer row (or main row). One then moves to the right arch and counts the teeth in the outer row and concludes with the inner row. Thus, in the example for family Cyprinidae the pharyngeal tooth formula would be written as 1,4–4,2. However, the number of teeth in each row is not 18 always uniform (e.g., 2,4-4,1), and you might see differences in either the main rows or lesser rows (e.g., 2,5-4,2 or 2,4-4,1). The common carp (Cyprinus carpio) has three rows of teeth to contend with, but the rules still apply: left arch (inner, middle, and outer portion) and then the right arch (outer, middle, and inner portion). The resulting count of pharyngeal teeth would be written as 1,1,3-3,1,1. Dorsal view of pharyngeal teeth of minnow spp., with arches rotated outward so teeth are visible Counting Pharyngeal Teeth 1 Dorsal view of pharyngeal teeth of common carp, with arches rotated outward so teeth are visible Dorsal view of pharyngeal teeth of sucker spp. Dorsal view of pharyngeal teeth of grass carp, with arches rotated outward so teeth are visible Counting Pharyngeal Teeth ...