Hydrophis platurus xanthos isn’t any old snake. This newly described subspecies is a shocking yellow color and hunts at night in extremely hostile waters using a technique never documented before by scientists.
As explained by marine biologists Brooke Bessesen and Gary Galbreath in the journal Zoo Keys, the sea snake can be found in the unusual environment of Golfo Dulce, located on the South Pacific coastline of Costa Rica, where waters are turbulent, low in oxygen, and as hot as 32.5°C (90.5°F). This temperature is around the upper limit of what this species can survive in.
To help cope with this sweltering heat, the sea snake has evolved a yellow coloration to reduce absorption of solar energy while feeding on the surface. However, if it can help it, it will hunt at night when the temperature is cooler. It hunts by floating on the water’s surface, coiled up in ambush posture, with its head and “neck” submerged in the water (image above). Here, it waits and opportunistically swallows down any small fish that come its way.
The snake can both breathe air and absorb oxygen through its skin, yet spends 99.9 percent of its time at a depth of 20 to 50 meters (65 to 164 feet), remaining submerged for up to 213 minutes per dive. Since the levels of oxygen are so low in Golfo Dulce, the researchers are pretty amazed it appears to be so comfortable in the water.
Its closest living relative, Hydrophis platurus, is a yellow sea snake that lives about 22 kilometers (14 miles) away in cooler waters. Since it’s so different to this sea snake, the researchers say their discovery might eventually turn out to be a new species altogether. However, the researchers say they need more data about the sea snakes before jumping to any conclusions.
As if this sea snake's life wasn’t hard enough, its geographic range – a mere 320 square kilometers (123 square miles) – is a currently unprotected, meaning the subspecies is at risk of extinction despite only just being recognized by science.
"Hopefully this globally unique population can continue to offer both scientists and conservation-conscious tourists a worthy subject of observation and study," say the authors.