A Perfect Planet

Episode
Episode 4 - Oceans
Broadcast Info
2021 (58 mins)
Description
Oceans are the largest ecosystem on Earth, covering 2/3rds of the surface of our world and providing half the oxygen in our atmosphere. It’s thought that they’re home to as much as 80% of all life on Earth, and nearly 3 billion people rely on them for their primary source of food. But if it weres not for one simple factor, our planet’s oceans would be little more than stagnant wastelands, and life on Earth - not just in the oceans - would cease to exist. So what is it about our Perfect Planet’s oceans that brings about so much life? The answer is that all the world’s oceans are connected - dip your toe in the sea off Cornwall, and you are connected to every ocean and sea on our planet. There are not five, separate oceans, but one, linked by a network of powerful currents that are forever on the move. Every drop of seawater on Earth rides these currents, taking a thousand years to complete a single circuit. All marine life depends on this continuous movement of water - from vast super-pods of dolphins and the flocks of gannets that follow them as they scour the oceans searching for a meal, to the tiny yet dazzling flamboyant cuttlefish that’s looking for a mate. All rely on currents to carry vital nutrients across the ocean - but currents are just part of the story. Other forces bring nutrients to our planet’s coastal regions, the most productive parts of our seas. Winds blowing across the open ocean create rolling swells that travel thousands of miles towards the coast. When these swells hit the shallows, massive waves are spawned that crash against the shore, stirring up nutrients to be exploited by countless species. For some, like blacktip sharks and trevally, waves create rich hunting grounds - but for others like rockhopper penguins, the massive swells that crash into their island home make returning back to their colony a potentially deadly commute. Our oceans are also driven by another force - the gravitational pull of the moon which causes the ocean to bulge at two points. Twice a day - every day - tides (timelapse)mix up the waters of our shallow seas creating new opportunities for huge amounts of life on both land and sea: the fast-flowing tides of Norway provide the perfect condition for filter feeding mussels, which are the favourite food of eider ducks, whilst more gentle tides like those seen in the Bahamas create the ideal opportunity for lemon sharks to give birth in the relative safety of flooded mangrove forests. Without this constant mixing from currents, tides and waves, our oceans would stop supporting life - and a healthy ocean is vital to a healthy planet.
Genre
Natural History; Oceanography

How to cite this record

The Open University, "A Perfect Planet". https://learningonscreen.ac.uk/ou/search/index.php/prog/238091 (Accessed 11 Jan 2025)