Papers in the Biological Sciences


Date of this Version



Published in INVESTIGATIONS OF THE ICHTHYOFAUNA OF NICARAGUAN LAKES, ed. Thomas B. Thorson (University of Nebraska-Lincoln, 1976). Copyright © 1976 School of Life Sciences, University of Nebraska-Lincoln.


Rostral tooth counts were made of 211 sawfish (Pristis perotteti) from the Lake Nicaragua-Rio San Juan System. The number of teeth is established early in development and it changes only on accidental loss of teeth, which are not replaced. The average number on the left side is equal to that on the right, but in individuals, either side may have as many as three more teeth than the other. Female tooth counts average 15.94 per side and range from 14 to 18, while males average 18.00 with a range of 16 to 20. Within litters, this dimorphism is also evident, but some· what less overlap occurs between sexes. On the basis of only three males and three females, P. pectinatus does not appear to exhibit the same dimorphism.