Ontogeny of osmoregulation in the estuarine ghost shrimp Callianassa jamaicense var. louisianensis Schmitt (Decapoda, Thalassinidea)
Abstract
During the abbreviated development of Callianassa jamaicense var. louisianensis Schmitt, both zoeal stages exhibit hyperosmotic regulation of hemolymph in media <800-900 mOsm and conform at higher salinities, a pattern similar to adults. Hyperosmotic regulatory ability is present at the time of hatching. (Na + K)-activated ATPase activity, commonly associated with salt-transporting tissues, increases from 7.8 ± 4.3 μmol Pi·h-1·g wet wt-1 (95 % CI, n = 7) at early stages of prehatch development to reach the highest levels at hatching (96.5 ± 10.6 μmol Pi·h-1·g wet wt-1, n = 21); thereafter, larval ATPase activity decreases and then stabilizes at 56.6 ± 12.4 μmol Pi·h-1·g wet wt-1 (n=21). AgNO3 stains potential sites for osmoregulation along the inside surface of the branchiostegite and adjacent body wall in the larvae by forming silver precipitates which are identified by energy dispersive X-ray analysis. TEM studies of these sites reveal a specialized epithelium with characteristics typical of salt-transporting tissue. Thus physiological, biochemical and morphological features present in these larvae reflect an early development of osmoregulatory ability. © 1986.