Sea snakes don’t drink salt water

While sea snakes live all their lives in sea water,  a University of Florida biologist has discovered that the actually will dehydrate for months just waiting for the next rainfall when they can drink their fill of fresh water.  Professor Harvey Lillywhite, a University of Florida biologist whose research was just released in the Proceedings of the Royal Society B, the flagship biological research journal of the Royal Society, says that his discovery contradicts the once unquestioned belief that marine vertebrates evolved to consume salt water.

In a recent news release he stated: “These snakes refuse to drink salt water, even when dehydrated.  They need fresh water to survive.”  Lillywhite reiterated that in spite of what current physiology textbooks state “no sea snake we have tested drinks sea water.”

Yellow-Bellied Sea Snake

Lillywhite and his international team of  researchers from the US, France and Australia, and a research team engaged in field studies and conducted experiments with the yellow-bellied sea snake (Hydrophis platurus) over a period of three years.  They studied sea snakes in Guanacaste, Costa Rica and learned that these reptiles have a camel-like quality in that they can for up to seven months without drinking water during the country’s dry season.

The snakes dehydrate very slowly.  During this process they can lose approximately 25 percent of their body mass.  When fresh water is available they will drink almost the same amount of mass in fresh water.  Their main source of fresh water is rain.

Rain is not as dense as sea water and it creates a “lens” on the surface of the sea.  Lillywhite and his research team report that snakes sense when rainfall is due and they swim towards the surface.  He reported: “We think they almost certainly know that it rains because their behavior changes during the approach of a tropical storm as the atmospheric pressure changes.”

Lillywhite added that decreasing rainfall could be the cause of diminishing populations of sea snakes in some places such as drought-stricken Northern Australia, where the sea snake numbers have been lessening for a decade and two local species are now believed to be extinct.

Lillywhite states that if the global climate change makes drought conditions worse, sea snakes and possibly other marine vertebrates that rely on rain for fresh water could be adversely affected.  He concludes: “Understanding the water requirements and drinking behaviors of marine vertebrates could help with conservation efforts.  In areas of intensifying drought, they will need to move or die out.”

(Image courtesy of EarthlyNation)