Episode two of Blue Planet II could be one of Sir David Attenborough's scariest shows yet - giving us a glimpse of life in total darkness that we are only just starting to explore. The episode also looks at peculiar gardens that are thriving in the pitch black as well as species of coral that have never been seen in shallower waters. The fangtooth (pictured) has the largest teeth relative to body size for any fish in the entire ocean. The filming of Blue Planet involved around 1,000 people from producers to deep sea divers, researchers to scientists, camera crews to helicopter pilots and drone operators. Some 125 expeditions were undertaken across every ocean, with 1,500 days spent at sea and 6,000 hours underwater.

A transgender fish fought a brutal stand-off with a rival male during the compelling first episode of David Attenborough's eagerly anticipated Blue Planet II. The award winning series returned to BBC One this evening, 16 years after its first season wowed viewers in 2001. After the shocking scenes in Sir David's Planet Earth II, which included a snow leopard being'raped' and a lizard making a seemingly impossible escape from an army of snakes, the broadcasting legend set a high bar. While the opening episode of his new series did not measure up for drama, it certainly delivered on the unexpected. Whisking viewers off to the coast of northern Japan, Blue Planet II revealed the bizarre mating ritual of the Asian Sheepshead Wrasse - a transgender fish.