WEIRD CREATURES OF THE DEEP

Meet the strange and wonderful animals living thousands of metres below the surface of our oceans

- SCOTT DUTFIELD

More than 80 per cent of the world's oceans are yet to be explored and mapped, meaning there's a lot we don't know about what lies beneath the surface. To say that the world's oceans are vast would be an understatement. Around 79 per cent of the entire biosphere of our planet is made of water that's 1,000 metres deep, and the place where the ocean reaches its deepest point is seven miles from the surface. Known as the Mariana Trench, this is a crescent-shaped trough that runs for more than 1,550 miles along the length of the Western Pacific Ocean.

It was first discovered in 1875 by HMS Challenger after sailors dropped a weighted rope about five miles into the ocean. In 1951, HMS Challenger II returned to the same spot and determined that there were two more miles to go before reaching the bottom. In 2012, Titanic director James Cameron descended to the Mariana Trench in a one-person submarine called Deepsea Challenger and spent four hours at a depth of seven miles below the surface, witnessing the deepest waters on Earth.

Life in the deep ocean exists in one of two places: the benthic zone or the pelagic zone. The benthic zone refers to the sedimented bottom or seafloor, whereas the pelagic zone is everywhere else - the open water of the ocean. These two general zones have subzones within them that describe the layers of the ocean moving down towards the deepest point on the planet, the Mariana Trench. Beyond the uppermost layer of the ocean, known as the epipelagic or sunlight zone, life has evolved to adapt to life in the cold, dark extremes of the deep sea.