Extraordinary footage of a rarely seen giant deep sea fish. The Oarfish

Extraordinary footage of a rarely seen giant deep sea fish has been captured by scientists.

Using a remotely operated vehicle, they caught a rare glimpse of the huge oarfish, perhaps the first sighting of the fish in its natural setting.

The oarfish, which can reach 17m long, has previously only been seen on a few occasions dying at the sea surface, or dead washed ashore.

The scientists also filmed for the first time the behaviour of a manefish.

Mark Benfield from Louisiana State University, Baton Rouge, US was undertaking a survey as part of the Serpent project, a collaboration between marine scientists and energy companies such as BP, Shell, Chevron and Petrobras working in the Gulf of Mexico.

Using remotely operated vehicles (ROV) provided by the oil and gas companies, the scientists are able to explore the deep like never before.

During one of these surveys, the scientists glimpsed a giant oarfish.

Sea serpent

Oarfish (Regalecus glesne) are one of the world's longest fish reaching 17m.

Their strange appearance may have provided the basis for the sea serpent myths told by early ocean travellers.

Not only are they elongated, they also have a prominent dorsal fin which gives it an unusual "serpent" appearance.