Dehydration and drinking responses in a pelagic sea snake

Area of Science:

• Marine Biology
• Herpetology
• Animal Physiology

Background:

• Amphibious sea kraits (Laticauda spp.) dehydrate in seawater and need freshwater to recover.
• Pelamis platurus is a fully marine, pelagic sea snake species.

Purpose of the Study:

• To investigate the water balance and hydration strategies of Pelamis platurus.
• To compare the dehydration and freshwater drinking thresholds of Pelamis platurus with sea kraits.

Main Methods:

• Field sampling of Pelamis platurus in Golfo de Papagayo, Costa Rica.
• Controlled laboratory experiments to assess dehydration and water intake.
• Measurement of body mass loss and drinking behavior in response to dehydration.

Main Results:

• Pelamis platurus dehydrates in seawater and drinks freshwater, not seawater.
• The dehydration threshold for drinking freshwater is approximately -18.3% body mass loss.
• Pelamis snakes drink larger water volumes and compensate for a greater percentage of dehydration deficit compared to sea kraits.
• Some individuals drank brackish water, but most preferred lower salinity or did not drink.

Conclusions:

• Pelamis platurus, despite being fully marine, experiences dehydration and actively seeks freshwater.
• This species exhibits a more advanced adaptation to marine life than sea kraits, with a reduced dependence on freshwater sources.
• The findings highlight the physiological challenges and adaptations of marine reptiles to water balance in oceanic environments.