Intestinal water absorption in Tilapia mossambica—I. Water movement in everted sacs of intestine bathed on both surfaces by identical ringer solution

Abstract

1. 1. The rate of intestinal water movement in Tilopia mossambica, adapted to fresh water (FW), sea water (SW) and double-strength sea water (DSW), was measured using everted sacs of fore-, mid- and hind-intestine. 2. 2. Sacs of fore-intestine from both SW and DSW fish showed a 2·5-fold increase over FW fish in respect to water movement from the mucosal to the serosal surface. In contrast there were only minor differences between the three groups in the rate of water movement by sacs of mid- and hind-intestine. 3. 3. These results indicate that the fore-intestine in T. mossambica functions so as to promote water absorption in salt water adapted fish.