Abstract
Some sea snakes and sea kraits (family Elapidae) can dive for upward of two hours while foraging or feeding, largely because they are able to absorb a significant percentage of their oxygen demand across their skin surfaces. Although cutaneous oxygen uptake is a common adaptation in marine elapids, whether its uptake can be manipulated in response to conditions that might alter metabolic rate is unclear. Our data strongly suggest that Yellow-Lipped Sea Kraits, Laticauda colubrina (Schneider, 1799), can modify cutaneous uptake in response to changing pulmonary oxygen saturation levels. When exposed to stepwise 20% decreases in aerial oxygen saturation from 100% to 40%, Yellow-Lipped Sea Kraits spent more time emerged but breathed less frequently. A significant graded increase in cutaneous uptake was seen between 100% and 60% saturation, likely attributable to subcutaneous capillary recruitment. The additional increase in oxygen uptake between 60% and 40% was not significant, indicating capillary recruitment is likely complete at pulmonary saturations of 60%. During a pilot trial, a single Yellow-Lipped Sea Krait exposed to an aerial saturation of 25% became severely stressed after 20 min, suggesting a lower saturation tolerance level between 40% and 25% for the species. Reducing subcutaneous perfusion could optimize swimming performance during foraging, whereas redirecting blood to skin surfaces would maximize dive times when subduing prey or avoiding aerial predators.
