A giant flesh-eating leech that is still a mystery to scientists has been filmed for the first time as it devours a huge earthworm like spaghetti. The glossy red eyeless creature resembles an alien from a horror film in the footage aired yesterday by the BBC. Filmed in the forests of Borneo, the yet-to-be-named animal is known by the tribes of Mount Kinabalu simply as the "giant red leech". It is one of the largest in the world, measuring about 30cm-long and believed to be able to grow larger, UK newspaper The Telegraph reports. In the footage captured by BBC filmmakers for the Wonders of the Monsoon documentary, the leech is seen creeping along a large earthworm more than double its own size, searching for an end to the worm's 78cm-long body before beginning to speedily suck it down. The worm puts up a fight but there is no escape from the leech's "crushing" muscular throat. Documentary director Paul Williams said the footage revealed the leech's predatory behaviour for the first time. "It was either searching for an end to grab, or was working out whether it was too big to eat," Williams told The Telegraph. "When it found an end it started to suck. It was incredible."