Snakes at sea: diving performance of free-ranging sea kraits
Résumé
Evolutionary transitions from terrestrial to marine life pose massive physiological challenges. Marine mammals and birds exhibit major adaptations of cardiovascular and respiratory physiology to increase the depths to which they can dive, and the time for which they can remain underwater. Marine reptiles have attracted far less attention in this respect, but we would expect ectotherms to outperform endotherms in several dive performances because ectothermy reduces oxygen demand. We surgically implanted dive-loggers in amphibious sea snakes (sea kraits, Laticauda laticaudata and L. saintgironsi) in the lagoon of New Caledonia, and recorded dive performance (e.g., depths, durations and post-dive intervals) for two free-ranging animals over periods of 8 and 11 weeks. During foraging excursions the snakes spent > 80% of their time underwater, diving > to 80 m and for periods of > 130 min. Inter-dive intervals were brief, typically < 45 sec, suggesting that dives were aerobic. Dive patterns in these animals differ in major respects from those of previously-studied marine endotherms, turtles and pelagic sea snakes