© 1968 by The Society for Integrative and Comparative Biology
Osmoregulation in Larvae of the Land-Crab, Cardisoma guanhumi Latreille
Aquatic Sciences, Inc., and Department of Biological Sciences, Florida Atlantic University Boca Raton, Florida 33432
Duke University Marine Laboratory Beaufort, North Carolina 28516
Daily studies were made of the osmoregulatory abilities of Cardisoma guanhumi from hatching to the end of larval development. These results were compared to those of similar research on osmoregulation by larvae and megalopa of four species of estuarine, littoral, and sub-littoral crabs. The comparison shows that larvae of C. guanhumi possess the same kinds of adaptations for water intake at the time of molt that were found in Rhithropanopeus harrisii. Land-crab larvae hyperregulated in 10 p.p.t. sea water and hyporegulated in water of 40 p.p.t. for experimental periods for 2 hr during the first one-third of their development. During the remainder of larval life, they hyporegulated against 15 p.p.t. in intermolt periods and became isosmotic with, or hyporegulated against, 10 p.p.t. at the time of molting. From the time of hatching, the osmoregulatory pattern of developing C. guanhumi fits them for deep penetration of estuaries and for crossing steep saline gradients. This pattern is evidence for a stronger and more enduring control of water balance, especially at the time of molting, than we have found in non-terrestrial species.