
TODAY COSTA RICA – Hanging upside down with its mouth open ready to pounce is the modus operandi of the yellow subspecies of sea snake discovered in Costa Rica’s Golfo Dulce.
The petite, all-yellow snake hunts that night, when it shows off a unique trait that distinguishes it from its close-relative, the yellow-bellied sea snake, feeds on small fish at night by hanging upside down from the water surface. It assumes a wave-like posture with its head pointing down and mouth open.

Unlike its related species, the yellow-bellied sea snake, the new yellow sea snake subspecies lives in a more hostile environment with warmer, turbulent waters.
The new subspecies of sea snake, called Hydrophis platurus xanthos, was described by researchers based at Phoenix Zoo, Northwestern University and The Field Museum of Natural History in Chicago.
It floats at the sea surface at night in a sinusoidal (wave) shape with its head pointing downwards and mouth wide open.
The new subspecies has a smaller body size and has a more uniform yellow colorationĀ which contrasts with the black and yellow lines and tail spots or bands of the typical species, however, the new subspecies can have black spots along its back.
Unlike its related species, the yellow-bellied sea snake (Hydrophis platurus), the new yellow sea snake subspecies lives in a much more hostile environment.

It lives in waters in the gulf which are warmer, regularly turbulent and contain levels of dissolves oxygen that occasionally drop to extremely low levels.
According to the researchers, the territories of the two snakes are separated by some 22 kilometers.
The fact that the two species live in such close proximity to each other could be the reason why the new reptile has evolved at night.
In addition, its lighter color compared to its close relative helps the snake play a role in thermoregulation – a process that allows the body to maintain its core internal temperature.