In the lab studies, Lilywhite's team kept snakes caught in the wild near Orchid Island, Taiwan, away from freshwater for two weeks. At the end of that period, dimpling of the snakes' scales indicated they were dehydrated.
The researchers weighed the snakes, freed them in saltwater tanks for up to 20 hours, then weighed them again. None gained appreciably, indicating they didn't drink, despite their thirst. But when the researchers freed the snakes to swim in freshwater tanks, most immediately drank significant amounts. More experiments revealed the snakes would drink only freshwater or highly diluted saltwater.
The kraits may get their freshwater from springs or streams around Orchid Island deed, the researchers observed far more sea snakes near these freshwater sources than in strictly marine sites, the paper says.
Lillywhite believes the sea snakes that spend their lives in the open ocean drink water from the "lens" of freshwater that sits atop saltwater during and after rainfall, before the two have had a chance to mix. That would explain why some seawater lagoons, where the waters are calmer due to protection from reefs, are home to dense populations of sea snakes the freshwater lens persists for longer periods before mixing into saltwater.
Rather than helping sea snakes gain water, the snakes' salt gland may help the snakes with ion balance moving excess salts from the bloodstream, Lillywhite said.
Some sea snake species living in dry regions may already be suffering as a result of climate change. Lillywhite said a colleague in Australia, which is in the midst of a historic drought, has observed declines and possible extinctions in some species at Ashmore Reef, ho
|Contact: Harvey Lillywhite|
University of Florida