A diagram of the main features of an area of ocean floor
Just like the Earth's landmasses, the oceans contain canyons, mountain ranges, and other formations. Learn about the different habitats for life they provide.
Sea floor sediments
The sea floor is carpeted with muddy sediment, made up of the remains of tiny plants and animals. They sank to the bottom of the sea after they died, along with volcanic ash and other materials carried from the land by rivers and winds. The sediment has built up over millions of years, so most of the sea floor is smothered by it to a depth of hundreds or even thousands of metres.
Large animals move over the sea floor, churning up the sediment, and water currents move it around. The carcasses of large animals from high up in the pile sink to the bottom, producing food hotspots for other creatures. From time to time, slumps and slides of sediment like avalanches sweep everything away.
Deep sea canyons
Canyons are breaks in the sea floor, like the Grand Canyon but in the ocean. Each one is very different. They can be difficult places to live because there are a lot of water currents that move the mud around. But this also means that they are home to animals like sponges, which don’t usually live in the slow-moving water of the deep sea. At the edges of the canyon there are terraces of mud, a gentler habitat where there are many worms that are unique to these canyon habitats.
Mid-oceanic ridge
In the middle of the abyssal plain (the deep sea floor) is a vast mountain chain - the mid-oceanic ridge system. It extends over 45,000km and crosses all the major oceans except the North Pacific.
In some places the ridge rises above the surface of the sea as oceanic islands like Iceland or the Azores.
Deep sea vents
Deep sea vents are springs of hot water flowing into the cold waters deep in the Pacific. The water was heated up by rocks deeper in the Earth before rising up into the oceans. It is full of chemicals that would kill many types of organisms. However, life has found a way to survive even in this hot and poisonous environment. Tubeworms and giant mussels are the main life forms in vents in the eastern Pacific, while in the Atlantic, shrimp are common. Due to the rich nutrients and warm temperatures, the creatures grow quickly. But if the vent stops producing its sulphide-rich waters then the animals must leave if they can or die.
