Body Fluid Solutes of Juveniles and Adults of the Euryhaline Bull Shark Carcharhinus Leucas from Freshwater and Saline Environments

Authors

Thomas B. Thorson, University of Nebraska-Lincoln
C. Michael Cowan, Associated Environmental Services Corp.
Donald E. Watson, University of Lagos

Date of this Version

1976

Comments

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.

Abstract

Since the discovery of the phenomenally high urea content of the body fluids of cartilaginous fishes by Staedeler and Frerichs (1858), the unique osmoregulatory system of this vertebrate class has been studied by many investigators. In broad outline, the mechanisms are essentially similar in all three of the major subtaxa: the selachians, the batoids, and the holocephalans. A single exception is the genus Potamotrygon (fresh-water stingrays of South America and Africa), which has apparently lost the ability to concentrate urea even when transferred to salt water.