Meeting Abstract

67.1  Thursday, Jan. 6  Freshwater drinking requirement in a pelagic sea snake, Pelamis platurus LILLYWHITE, H.B.*; SHEEHY III, C.M.; University of Florida, Gainesville; University of Texas, Arlington hblill@ufl.edu

Dehydration and procurement of water comprise key problems for vertebrates that have secondarily invaded marine environments. Sea snakes and other marine reptiles were previously thought to remain in water balance without consuming fresh water (FW) owing to the ability of extrarenal salt glands to excrete excess salts obtained either from prey or from drinking sea water (SW) directly. However, we learned recently that 3 species of sea krait (Laticauda spp.) require fresh drinking water and actually dehydrate in SW. To date, representatives from 4 of 5 principal clades of marine snakes are known to require fresh drinking water, but data have been lacking for the most specialized clade of marine snakes, the hydrophiine sea snakes. We investigated dehydration and drinking behaviors in the Yellow-bellied sea snake, Pelamis platurus, in Costa Rica. This species is pelagic and ranges from coastal waters of southeastern Africa to the Pacific waters of Central America. As with sea kraits, Pelamis that we dehydrated either in air or in SW refused to drink SW, but drank FW to remain in water balance. The dehydration threshold before drinking was 21.07 ± 0.9 % loss of body mass, which is about twice that of sea kraits. Compared with sea kraits, Pelamis dehydrate more quickly when exposed to air but maintain low rates of water loss in SW. From 10 to 12% of snakes collected from the Guanacaste coast of Costa Rica drank FW immediately when presented with the opportunity during the dry season, indicating they were in negative water balance. Thus, we conclude that some individuals dehydrate in their natural pelagic environment at sea. Supported by NSF IOS–0926802 to HBL.