- 20 minutes ago
Category
📺
TVTranscript
00:00Where land meets sea.
00:08Shaped into different habitats over time.
00:15Each a stage telling its own story.
00:20It was here waves washed the very first creatures onto the shore.
00:32Since then, this boundary joining two realms has given rise to a profusion of life.
00:40And by harnessing nature's most powerful forces, our coast continues to write new chapters in the story of life.
00:53Take a dive into our planet's mesmerizing world of water.
01:10From the monumental open ocean to the rugged coasts that serve as the dividing line between two worlds.
01:26From the changing rivers that carve through continents.
01:33To mysterious lakes and swamps.
01:36Immerse yourself in the magic that unfolds.
01:46As we reveal...
01:49The secrets of our enchanted waters.
01:53The coast can offer a variety of opportunities to many different creatures.
02:12A refuge.
02:14A source of food.
02:15Or for those smart enough.
02:19It can even be deployed...
02:21As a trap.
02:24Beneath the waves.
02:28A silent shadow glides through the waters of the North Atlantic.
02:32Sleek.
02:36Powerful.
02:38And clever.
02:40Orca are one of the animal kingdom's most intelligent hunters.
02:52With a playbook of tactics they can call upon in any eventuality.
02:57This female is heading towards the coast.
03:09She knows this world intimately.
03:12Every twist of shoreline.
03:14Even the contours of the shallow seabed have been committed to memory.
03:24She and her pod have been visiting this area for years.
03:28For years.
03:31They've devised a well-rehearsed strategy to hunt their favourite prey.
03:39The harbour seal.
03:48Everyone in the pod knows the plan.
03:51The changing tide is going to offer the best odds.
04:08As the water level rises, the seal's sanctuary of rocks starts to disappear.
04:15And the deeper water allows the orca to get much closer to the coastline.
04:22As she approaches, the seals instinctively head to the refuge of land.
04:29But it's all part of the orca's plan.
04:32Subtly driving one seal into a channel of deeper water, flanked by rocks.
04:38Then the pod splits up, making sure every escape route out of the channel is sealed off.
04:46Except one.
04:48The youngest orca shadows his mum.
04:51Go too shallow, and they risk getting stranded.
04:55But she knows from experience exactly how far she can push it.
05:05The seal is fooled into thinking it has found a way out of the channel.
05:11But its escape is blocked by the waiting pod.
05:14Who drive it from the safety of land, out into the open sea.
05:24It's now a game of cat and mouse.
05:33The seal may be fast, but the orca are faster.
05:37The strike is swift.
05:44And lethal.
05:47Teamwork, shared knowledge, and a deep understanding of every patch of this coastline.
05:51Have elevated the orcopod into formidable hunters.
05:55Learn how to use its powers, and the coast can be a very accommodating ally.
06:01An ever-changing state of the sea.
06:03The sea.
06:04The sea.
06:06The sea.
06:07The sea.
06:08The sea.
06:09The sea.
06:11The sea.
06:12The sea.
06:13The sea.
06:14The sea.
06:15The sea.
06:16The sea.
06:17The sea.
06:18The sea.
06:19The sea.
06:20The sea.
06:21The sea.
06:22The sea.
06:23The sea.
06:24The sea.
06:25The sea.
06:26The sea.
06:27The sea.
06:28The sea.
06:29The sea.
06:30The sea.
06:31The sea.
06:32The sea.
06:33The sea.
06:34The sea.
06:35The sea.
06:36The sea.
06:37The sea.
06:38The sea.
06:39The sea.
06:40The sea.
06:41The sea.
06:42The sea.
06:43The sea.
06:44The sea.
06:45The sea.
06:46The sea.
06:47first step into a new world.
06:54These guillemots are perennial seabirds, but this summer they are compelled to seek out
07:01a clifftop home so they can raise a chick, alongside tens of thousands of others.
07:17It's the only time the birds ever spend on land, but it's not a pleasant stay.
07:27Each family is perched on a ledge only a couple of inches wide.
07:33As guillemots raise just one chick a year, there's no room for error.
07:43Their eggs are even pear-shaped to prevent them from rolling off into the sea.
07:50Nope, this one's not going anywhere.
07:56And once the eggs hatch, the ledge becomes even more cramped.
08:03But as uncomfortable as their coastal home is, Dad still has access to food.
08:09It's just a bit further away.
08:14He takes turns with his partner, fishing these abundant coastal waters to satisfy the chick's
08:20ever-growing appetite.
08:25But every trip to the sea leaves the chick vulnerable, with just one parent to stand guard.
08:32Their nest is surrounded by neighbors, equally protective of their young.
08:45And hungry gulls threaten from the air, and closer to home.
08:54They too have been lured here by the coast's opportunities.
09:01It's time for the young guillemot to move on.
09:11The ocean is calling below them.
09:24Dad fights his way to a jumping-off point.
09:31It's just a short flight for an adult.
09:35But it's a giant leap for his chick.
09:40Only a few weeks old, and without fully developed wings, the chick can't yet fly.
09:52But he can fall.
10:08And Dad is right behind him.
10:22The escape plan pays off.
10:32These coastal seas are teeming with food, allowing Dad to dive around the clock, delivering twice
10:43as much fish than if they'd remained on land.
10:49Every summer, thousands of young guillemots take this leap of faith, some reluctantly.
10:58Plunging into the depths to join the others in this more welcoming world, free from the confines
11:07of the land.
11:08From now on, it's the Dad that takes on soul-parenting duties, ushering the chicks into the next chapter
11:18of their lives, as a real sea bird.
11:26Here, the chick will mature into a skilled swimmer, even before he learns to fly.
11:31He'll grow faster in the water, and will spend as many as five years constantly out at sea.
11:44Only returning to these cliffs when it's his turn to become a dad.
12:00These towering sentinels of the coastline have been sculpted by the onslaught of waves.
12:08But the ocean has another power it can harness to drive the movement of its waters.
12:21The rhythmic ebb and flow of every coastline is motivated by its tides, high and low.
12:32This pulse is driven by a force far beyond our world.
12:42The moon wields a secret power over our seas.
12:50Its gravitational pull causes the oceans to bulge out on the side closest to the moon.
12:58But also, it leaves a second bulge on the opposite side, farthest away from it.
13:06It's these bulges that create high tides.
13:11As the earth spins, the oceans rise and fall in an eternal cycle.
13:21The position of the sun and the earth's orbit also exert their influence, magnifying the
13:26seasonal push and pull.
13:31As the incoming water plays one of the most important roles in the coastal ecosystem.
13:40It's this constant motion that brings a wealth of goodness from the deep ocean to the shallows.
13:53Mix this marine fertility with sunlight, and a share of the land's rich nutrients.
14:01And coastal waters are transformed into some of the most productive areas of the world's oceans.
14:14All our shorelines are brimming with life.
14:25All sustained by the tidal waters.
14:31All our shorelines are bringing a gateway for creatures to switch their allegiance between land and sea.
14:38All our shorelines are brimming with life.
14:50Scotland's intricate coastline of jagged cliffs and rocky bays work with the strong tidal currents to make sure deep sea nutrients are delivered directly to their shores.
15:01Making the coast so bountiful, it has converted one staunch river dweller into an ocean expert.
15:08This otter mum and her three-month-old pups are waiting for the low tide.
15:17They are officially river otters, but the bounty of food here is too good to ignore.
15:33If you know how to find it.
15:40And mum is ready to deliver a lesson in coastal living.
15:54First, see what the tide left behind.
16:00Stranded amongst the heaps of seaweed by a whole host of creatures.
16:15Looks like the female pup has cracked it.
16:27Just beyond the land, the intertidal zone is packed with even more crabs, mollusks, and fish.
16:37But that means braving the sea.
16:42River otters are used to hunting in water.
16:45But these pups must get to grips with salt water, strong currents, and powerful waves.
16:52As they dive to scour the seabed for food, the growing swell proves too much for the female pup.
17:10But this is a great spot to watch and learn from the best teacher.
17:26It's octopus for dinner.
17:39And mum has her own way of, quite literally, disarming it.
17:44While the female pup prefers to study from afar, her brother is fast getting familiar with the seafood.
17:57As fruitful as these waters are, the otters are not designed for swimming in the sea.
18:17And their fur requires some aftercare to keep it in the best condition.
18:24So mum encourages them to rub themselves in the seaweed.
18:28This sloughs off any salt residue, helping keep their coats waterproof to insulate them from the cold seas.
18:36It's a minor inconvenience when the living here is this good.
18:48So good, that half of Scotland's river otters have now adapted to live on the coast.
18:55And they're a valuable addition to the area.
19:04As top predators, the otters will help maintain the balance of this tidal ecosystem.
19:12Just as they would in a river.
19:17By preying on the most abundant species, they keep populations in check, helping to maintain the diversity in these waters.
19:40Away from the strong tides and crashing waves.
19:46A tranquil, sandy beach offers a more welcoming side of the coastline.
19:57Setting the scene for a special appearance from a so-called living fossil.
20:03This female horseshoe crab is carrying thousands of eggs beneath her shell.
20:16She's one of hundreds of females that are coming inshore to find a mate and lay their eggs.
20:24More closely related to spiders than modern crabs,
20:29these tiny tanks predate the dinosaurs and have survived multiple mass extinctions,
20:38remaining unchanged for over 450 million years.
20:44So they know what they like when it comes to finding a suitable coastline.
20:50First, these ladies like to take life easy when they're carrying eggs.
20:57So they want a sheltered shoreline, free from powerful waves that might bowl them over.
21:06And they prefer a gentle slope to the beach.
21:09No hiking up the soft sand for them.
21:13The type of sand is also important.
21:16It must be coarse enough to allow proper drainage.
21:20And create pockets of air to oxygenate the eggs once she's laid them.
21:27There is one bit of coastline that fits all these criteria.
21:33Delaware Bay in North America.
21:42Which is why horseshoe crabs have been using this area as their spawning grounds
21:47since it became a tidal bay over 4,000 years ago.
21:54It's the right location.
21:57Now she needs to reach the actual beach.
22:02But in her way are a gamut of males, eager to fertilize those eggs of hers.
22:12She doesn't get to pick who.
22:15It's more a case of who gets there first.
22:21As she tries to battle through, the males attempt to sabotage each other's efforts.
22:29It's slow motion, armor-plated, chaos.
22:43Finally, she emerges, with one determined male clasped onto her shell.
23:04Once out of the water, she digs a hollow in the grainy sand and releases her eggs.
23:12And her hanger-on gets his reward.
23:17To fertilize them.
23:23Over the coming nights, as the tides rise and fall,
23:27this ancient act will play out again and again.
23:34Over 30 million horseshoe crabs visit this special bay during breeding season.
23:41With each female laying up to 100,000 eggs.
23:46But as she heads back out to the open sea, her precious offspring are already being devoured.
24:04The trillions of crab eggs serve a purpose far beyond their species.
24:17Thousands of migratory shorebirds time their arrival specifically to coincide with this spawning event.
24:29A stopover at this bay holds enough food for these sandpipers to fuel the next leg of their migration across the globe.
24:46And high tide delivers a share of the banquet to the fish and crabs waiting in the shallows.
24:59An intricate food web creating a bond between land, sea and sky that has lasted for eons.
25:10Fortunately, the sheer abundance of eggs ensures plenty will still develop safely beneath the sand.
25:18To guarantee the next generation of one of Earth's oldest survivors.
25:27The horseshoe crabs have found a specific beach that works for them.
25:37But there are countless different types out there.
25:46Sand's colour depends on its origin.
25:50Black sand comes from volcanic rocks or cooled lava that shatters into tiny fragments.
25:56Pink beaches get their attractive hue from the crushed up shells of tiny marine creatures washed ashore.
26:07But for most sandy beaches, their journey starts high in the peaks millions of years ago.
26:15As mountains slowly crumble under the persistent work of wind and rain, great shards of rock break free and tumble into rivers below.
26:35Carried downstream by churning currents, they break into fragments and are slowly ground into smaller pieces.
26:50Once at the coast, powerful ocean waves and shifting tides take over, grinding the once mighty stones down even further.
27:03The more energetic waves create pebble beaches as the power of the water throws rocks up the slope before they have the chance to be worn down.
27:15While more sheltered beaches create waves with less energy that repeatedly smooth over the same areas, breaking pebbles down into fine grains of sand.
27:31But in tropical waters, most of the fine white sand that looks so idyllic comes from a more surprising source.
27:40Parrot fish.
27:44Blessed with teeth harder than iron, they chew up chunks of coral as they graze algae off the reef.
27:54Each parrot fish can produce up to 1,000 pounds of this fine white sand each year.
28:19In the Caribbean, it's estimated that 70% of that beautiful, pristine sand has been pooped out by a parrot fish.
28:28When sea and sand work together, they can create a special magic to help determine the future of an entire species.
28:37The ocean is home to this green turtle.
28:50She's traversed its deep waters in search of food.
29:09But now she's heading inshore.
29:18Where better to lay her eggs than the exact beach that first welcomed her into the world?
29:28She has navigated her way over 1,000 miles to return to this one spot, using the sea floor as her compass.
29:40From the moment she was born, she's been creating a magnetic field map, starting with her birthplace, and then all across the ocean.
29:52A mental map that now guides her back to the coast.
30:06She is built for elegance in the water.
30:12But a sandy beach is the perfect terrain to lay her eggs, as long as she picks the right spot.
30:22For sea turtles, it's not chromosomes that'll determine the sex of their offspring.
30:28It's the sand.
30:32If the sand is too cool and moist, the clutch will all be male.
30:39Too dry and hot, and all females will emerge.
30:45A mix of sexes is the ideal, so she needs to judge the position of her nest just right.
30:53And let the sand work its sorcery.
30:58She scoops out a sandy vault nearly three feet deep.
31:08Fit for a hundred precious eggs.
31:15But she won't stay to look after them.
31:22She leaves that job to the beach.
31:28For the following two months, the sand protects and incubates the eggs.
31:44Then the tiny hatchlings finally break through the sand.
31:56These newborns, barely two inches long, are swimming machines.
32:04Programmed to just...keep...going.
32:11They instinctively head down the beach toward the light reflected off the ocean.
32:17But even under the cloak of darkness, their 300-foot dash to the sea is not easy.
32:32An army of ghost crabs block their route.
32:39They might not be much bigger in size.
32:44But these guys carry weapons.
32:47And they have been waiting for this moment.
32:56The late developers hope a daylight escape might offer better chances.
33:13But they too must navigate past the waiting crabs.
33:28The survivors are greeted by the surf, but they're not out of danger quite yet.
33:38Despite never having seen water before, instinctively, their ocean compass kicks in.
33:45At just a few minutes old, the tiny swimmers can read the push and pull of the water as the waves pass overhead.
33:58Using its direction, they orient themselves to swim straight out to sea.
34:04To escape the shoreline and the predators that might lurk in the shallows.
34:11Only one in a thousand green turtles make it to adulthood.
34:17Where they'll disappear into the deep.
34:23With such low survival rates, these turtles rely on protected natal grounds to give hatchlings the best start.
34:33But with the loss of these vital beaches, many sea turtle populations face an uncertain future.
34:51The coast is the final stop on the sea's journey.
34:57While tides and waves are instrumental in delivering nutrients to the shorelines,
35:02they also leave behind any unwanted ocean detritus.
35:09But there's no such thing as waste in nature.
35:20This bubbler crab is very pleased with his setup.
35:24He has fought off the competition to secure his own piece of beach territory.
35:31He just needs to dig himself a burrow and his home will be complete.
35:36Not bad for a creature the size of a little fingernail.
35:40And as the high tide starts to creep in, his food is delivered right to his door.
35:49Once the water has gone, he gets stuck straight in.
35:55But it's not the sand itself he's after.
35:58Each grain is coated in a thin layer of organic matter.
36:04A delicious mixture of decomposing plants and rotten plankton.
36:10Which are scraped off each grain as they pass through his mouth.
36:23Then the clean, indigestible sand is formed into neat little balls by his pincers.
36:32But he's not the only one emerging to feed.
36:37He shares the shore with other hungry bubbler crabs.
36:43Each one sticks within its territory, creating its own sandball galaxy.
36:50Which help to define boundaries and guarantee no time is wasted filtering the same patch of beach twice.
37:05But this legion of busy bubbler crabs aren't just insatiable gluttons.
37:10They're also inadvertently helping to maintain this coastline.
37:14Their appetite for rotting matter means they're actually cleaning every single grain of sand as they eat.
37:24Leaving behind a healthier beach.
37:29And as they work the sand into their signature bubbles, they aerate it.
37:34And help distribute nutrients throughout the entire beach ecosystem.
37:40Once again, the changing tide signals feeding time is over.
37:45Better retreat back to his burrow and wait for this new high tide to deliver a fresh coating of food across the sand.
37:58Every coastal creature, however tiny or giant, works with the ocean to help maintain their shoreline ecosystem.
38:08But the ocean can be an unpredictable partner.
38:13Its immense force means the coast is often required to take on yet another role.
38:20That of protector.
38:29Our coasts are the last line of defense against the power of the ocean.
38:34Natural coastlines have built-in fortifications that protect land against flooding, erosion, and storms.
38:49But only 15% of the world's coastlines remain in their native state.
38:55And one of the most threatened is the mangrove forest.
39:00Here, these remarkable salt-tolerant trees temper the water's energy by slowing its flow.
39:11Filter contaminants from the water, and anchor the coastline firmly in place.
39:18These super trees are also among the planet's most important carbon sinks.
39:30They remove more carbon dioxide from the atmosphere than terrestrial trees.
39:38And store it away in the surrounding soil.
39:41But for the wildlife that live amongst the mangrove trees, they serve an even more immediate purpose.
39:49A much-needed refuge.
40:02Hidden amidst the mangrove roots lies a world of growth and learning.
40:08And a secret school for cold-blooded killers.
40:18As the mangrove trees stretch their gnarled fingers into the shallows, they form a natural barricade to keep out large predators.
40:27Creating a safe place to cradle the fragile beginnings of countless tropical fish.
40:38However, this nursery is also home to baby sharks.
40:48They may be natural-born killers.
40:53But right now, like all the others here, they're just inexperienced young fish.
41:02For the juvenile lemon sharks, this is a sanctuary and a school.
41:15Born in these clear and calm coastal waters, they were left alone to fend for themselves.
41:22But without a parent around to guide them, how do these lemon sharks mature into an apex predator?
41:31By learning from one another.
41:35The youngest pups join up with slightly older juveniles, where they can observe the basics.
41:42Where to find food.
41:44Where to hide.
41:46And any dangers to avoid.
41:49With that groundwork complete, they then form peer groups of the same age, size and similar level of expertise.
41:58Essentially, these young sharks are making friends and hanging out together.
42:05Learning through adventure and mistakes.
42:12But this shark school is only possible because of the mangrove forest they're born into.
42:18This protective enclave provides them with plenty of food.
42:26Warm waters to help them grow.
42:28And a safe learning ground to practice their hunting skills.
42:39And if one shark learns a new trick, like how to stir up the seabed to flush out buried crustaceans.
42:47He'll show his friends how to do it too.
42:54After years, the group is ready to leave the sanctuary of the mangroves.
42:59And together, they venture out into the big wide ocean.
43:04Unlike most sharks, their species is surprisingly social.
43:09And learns through shared knowledge, showcasing a higher intelligence.
43:16The bonds they form in these coastal shallows set them up for life.
43:21It's not known if the friendships made in their youth remain throughout adulthood.
43:27But the lessons they learn there certainly do.
43:32Every part of our coast is different.
43:37And so too are the needs it caters for.
43:42Offering support, food and sanctuary.
43:47These precious habitats are essential to the future of life along the water's edge.
Be the first to comment