This captivating footage shows an endangered blue-coloured tarantula - considered such a mystery even scientists are scratching their heads.
Bizarre video shows the hairy spider with its distinct navy-blue tint crawling up and down a man's hand before climbing his arm.
According to reports, the creature is a young female Poecilotheria metallica - a critically endangered species of tarantula.
Mystery surrounds why the tarantulas have a blue-coloured hue.
In November 2015, National Geographic reported a team of US researchers set out to solve the puzzle but were left empty handed.
The creature is a young female Poecilotheria metallica - a critically endangered species of tarantula
Biology graduate Bor-Kai Hsiung, from the University of Akron in Ohio, concluded blue colouration in tarantulas probably evolved at least eight times.
Blue-coloured spiders are not believed to be uncommon with at least 40 species in different shades, according to The Verge .
But the reasons behind their bright colouring has yet to be explained.
The bright-coloured spider was filmed crawling up a man's arm
Mr Hsiung said: "The blue color definitely has a major function, and it's very specific why they need this color.
"We just don't know what that function is yet.
"We didn't find the answer to that question."
The video was provided by Barcelona resident Daniel Valcarcel and was uploaded to ViralHog.