A new species of boa constrictor with silver scales has been discovered on a remote Caribbean island.

Scientists identified 20 of the 3ft-longĀ Silver Boa snakes during two expeditions to Conception Island Bank and neighbouring islets in the Bahamas.

The snakes – Chilabothrus argentum – have a distinctive silver colour. They were given the name Silver Boa after the first specimen was found climbing a Silver Palm tree.

A US research team, led by Dr Graham Reynolds from Harvard University, determined it was a previously unknown species after analysis of tissue samples.

Dr Reynolds discovered the snake after it slithered on to his head as he slept on a beach.

Robert Henderson, an expert on boa constrictors from the Milwaukee Museum of Natural History, said: “Worldwide, new species of frogs and lizards are being discovered and described with some regularity.

“New species of snakes, however, are much rarer.

“The beautiful Bahamian Silver Boa, already possibly critically endangered, reminds us that important discoveries are still waiting to be made.”

The Silver Boas were electronically tagged before being released back into the forest on the island.

They are said to be critically endangered, according to the International Union for Conservation of Nature, and are under threat from feral cats on the island.

Boa constrictors wrap their bodies around their prey, causing them to suffocate. Boas in the Bahamas eat frogs, birds and rats.