Wild Isles

Episode
Ep5 - Ocean
Broadcast Info
2023 (58 mins)
Description
Sir David Attenborough explores the surprisingly vibrant seas that surround the British Isles. The vast watery wilderness around us is over three times the size of our land mass, and yet to many, our oceans remain a mystery. Full of colour and teeming with life, the seas of Britain and Ireland are crucially important to a range of wildlife. This episode will take viewers beneath the waves to uncover the thriving habitats that exist along our 22,000-mile coastline. In winter, clear evidence of the ocean’s abundance can be seen on a beach in Norfolk. Thousands of grey seals congregate on the shoreline to give birth. Britain and Ireland are home to 40% of the world’s population of grey seals, and the number being born on our shore rises every year. The newly-born pups depend on their mothers for the first few weeks of their lives, but once weaned, the females are ready to breed again. This is the moment the males have been waiting for. Heavy-weight males enter violent, bloody fights to win a stretch of beach, and the females along with it. Beyond the beach, the vibrant shallows contain several important habitats. Rich beds of sea grass are nurseries for a range of animals, while also acting as very important carbon storage areas. They are also home to one of the strangest fish in our waters - the sea horse. We follow a male and female as they perform a balletic mating dance in the water, delicately entwining their tails. The stakes are high, as these animals mate for life. In deeper water, patterned cuttlefish prowl the water on the hunt for food. When night falls, tiny algae floating in the water alert the cuttlefish to nearby prey. Producing bright flashes of light when disturbed, the bioluminescence allows the cuttlefish to snatch their victims, even in the dead of night. Some animals, like the spider crab, undergo a mass migration along the shallow seabed. For just a few days every year, thousands of crabs march together forming a huge mass of bodies. Others, like the slow-moving royal flush sea slug have a more mesmerising way of migrating. They use the water currents to carry them to new and food-rich areas, using their bodies like wings to swim upwards and drift. At the most northerly point of the British Isles are the Shetland Islands. The undisturbed coastline here is a stronghold for more than a thousand otters. We follow a fearless young otter as it dives to the sea floor, turning up rocks in search of fish and crabs. They need to catch enough prey to keep warm in the frigid northern water. Thankfully, the pickings here are rich. The seas around the British Isles are constantly moving, in part due to the warm Gulf Stream and its massive tides. The Severn Estuary experiences the third largest tidal difference in the world, with water that rises and falls by as much as 14 meters, twice a day. Where the water is forced through narrow gaps along the coast, powerful currents are created. The most awe-inspiring is the Corryvreckan Whirlpool on the Scottish west coast - the third largest whirlpool on the planet. The currents mix the water, recycling nutrients which travel up to the surface. Here, the penetrating sunbeams fuel fresh life, and our waters become a rich soup of tiny floating algae. They serve as food for a group of alien-looking animals called the zooplankton, which are in turn a crucial food for our largest fish, the Basking shark. Growing up to the length of a double decker bus, this gentle giant filters the water open-mouthed, feeding exclusively on the tiny zooplankton. Herring and mackerel form huge swirling shoals as they too feed on plankton, and this attracts the attention of aerial hunters. Gannets plunge dive at speeds of more than sixty miles an hour to snap up the fish. As they hit the surface, they fold their wings back to avoid them breaking on impact. Our seas support 65% of the world’s population of gannets, as well as another important sea bird - the Manx shearwater. Almost the entire world population of Manx shearwater comes to the British Isles every summer to nest and feed. In a touching piece to camera, Sir David Attenborough bids a fledging chick farewell as it embarks on its six-thousand-mile journey across the oceans to South America. There is no better example of how important the British Isles and its abundant seas are to the survival of wildlife worldwide.
Genre
Natural History

How to cite this record

The Open University, "Wild Isles". https://learningonscreen.ac.uk/ou/search/index.php/prog/244769 (Accessed 10 Jan 2025)