Planet Earth III episode 2 – Ocean – The vast majority of our planet remains an enigma, hidden beneath the waters of the ocean, which envelopes two-thirds of the Earth and shelters 80% of all animal species. Yet, our knowledge of this realm remains superficial. Sir David Attenborough’s latest film takes us on an enthralling voyage across this expansive marine landscape, unveiling the captivating behaviors and adaptabilities essential for aquatic survival.
Tropical waters, though appearing idyllic, are treacherous battlegrounds. Here, even menacing predators like the lionfish tread cautiously. The clown frogfish, an unparalleled hunter of the reef, boasts a fishing rod on its head, its bait – a shrimp-like creature, is irresistibly deceptive. Moving away from the warmth, the chilly waters off North America nurture expansive forests of kelp, a habitat perilous for the young horn sharks. Within these green walls, giant sea bass lurk, but the most formidable threat lies hidden below. A naive horn shark might fall prey to the lurking angel shark, consumed in a blink, yet it’s armed with an unforeseen defense.
The open ocean’s expanse thrives on floating seaweed islands. However, plastics, with an annual influx of 12 million tonnes, are replacing these natural sanctuaries. Enter the Columbus crab. Despite being poor swimmers, these crabs ingeniously hitch rides on turtles, offering grooming in exchange for shelter, exemplifying nature’s ingenious mutualism.
Venturing deeper into the ocean uncovers an enigmatic world. Special vessels are essential to navigate these profound depths where sunlight is a mere memory. The wonders here include the colossal siphonophore, dwarfing even the blue whale, and the gulper eel, capable of consuming prey bigger than itself. Deep down, near the ocean floor, the chilling waters house the pearl octopus. Mothers journey to thermal spas, warm zones where they lay eggs. Despite the faster egg development in these areas, the nurturing lasts two years, during which the mother’s unwavering vigilance leads to her ultimate sacrifice.
Today’s marine life faces competition from humanity, and their adaptability will determine their future alongside us.
Planet Earth III episode 2 – Ocean
A groundbreaking journey from tropical shallow seas to the mysterious depths. Sir David Attenborough reveals extraordinary new worlds and unique animal behaviours in the ocean.
The Tropical Shallows: An Arena of Deception and Surprise
The turquoise waters of the tropical shallows may seem like paradise, but they are in fact a competitive arena where only the most cunning survive. Here we find masters of camouflage and deception, each with their own ingenious tactics.
The lionfish is one such cunning inhabitant, using its venomous spines and camouflage to navigate the reefs with caution. Potential predators quickly learn to avoid this master of disguise. However, the lionfish does face one unlikely foe – the clownfish. While no match in size, clownfish have evolved immunity to lionfish venom. They can fearlessly nip at the fins of bigger lionfish that encroach on their territory. Their colourful bands also serve as a warning. This reveals how even the mighty lionfish treads carefully in the treacherous shallows.
Meanwhile, the peculiar clown frogfish has developed an entirely different survival strategy. Using a lure shaped like a shrimp on its head, it can angle and dangle the “bait” to draw in prey. With lightning quickness, it then sucks unsuspecting fish into its oversized mouth. This astonishing and unique hunting mechanism enables the relatively small clown frogfish to take on much larger prey.
The tropical shallows are full of such tricksters and deceivers. It is here we truly understand the lengths some creatures will evolve to in order to survive in an environment where danger lurks behind every corner.
The Forests of Giant Kelp: Refuge and Risk
Along the rocky coastlines of California arises the magnificent giant kelp forests. These golden brown fronds provide vital nursery habitat for juvenile species like sea otters and sharks. But even in this sun-kissed landscape, risk is ever present.
The young horn shark is one timid inhabitant navigating the kelp stalks. While its camouflage offers some defense, it faces threats from all sides – from giant sea bass ambushing from the depths, to even bigger adult sharks patrolling the peripheries. However, an even greater menace lurks unseen in the shadows of the kelp – the stealthy angel shark.
With its flattened shape and sandy coloration, the angel shark is almost invisible as it lies buried in the sediment. When unsuspecting prey draws near, in an explosive burst it arches its body to ambush the victim, sucking it into its jaws within seconds. This lightning fast reaction makes it a formidable predator. Young horn sharks must tread softly to avoid becoming a surprise meal.
Yet the horn shark has an ingenious survival adaptation when caught by the angel shark. Its spine is lined with sharp hooks that anchor into the predator’s throat, choking the angel shark into releasing its prey. The tables quickly turn through this surprising defense mechanism.
As seasons change, strong storms batter the kelp forests, ripping up stalks and scattering rafts of floating kelp offshore. But even uprooted, the kelp provides a lifeline to species seeking refuge.
Open Ocean Oases: Shelter in a Sea of Blue
When enormous rafts of kelp get swept out from coastal habitats, they become literal and figurative oases in the open ocean. Adrift on the currents, these floating islands provide rare shelter and food for creatures brave enough to explore the vast blue.
Schools of predatory blue sharks often follow the floating kelp mats, hunting for oblivious fish drawn to the cover. But some species have adapted to turn the sharks’ hunting ground into their own refuge.
The aptly named flying fish launches itself nearly 30 feet in single gliding leaps to escape predators below. At night they seek the shelter of floating kelp to lay their adhesive eggs safely out of reach of patrolling sharks. Their remarkable gliding ability enables them to exploit the open ocean, avoiding dangers lurking in the water column.
While fluttering through the air, flying fish often lay eggs on the underside of the drifting kelp, hidden from predatory eyes. These oases of vegetation provide rare havens of opportunity far from shore, for those bold enough to survive in the pelagic realm.
The Allure and Acrobatics of Courtship
Gathering along coastlines, male humpback whales burst into song, serenading mates in a timeless ritual. But beneath the waves, courtship takes on even more extraordinary forms.
In the crystalline waters of Mexico’s Sea of Cortez, a supersized gathering occurs each winter. Thousands of mobula rays converge in a spectacular courtship display as suitors compete to mate. It begins with the males riding females, waiting for the moment they release eggs. At the pivotal moment, multiple males rush in to fertilize them.
To attract the discerning female, competing mobula perform jaw-dropping acrobatic leaps, cartwheeling up to six meters out of the water. Their pectoral fins have evolved to enable such graceful maneuvers. This daring display comes at a cost however, as it attracts the attention of their most feared predator.
The Perils of Attraction
The slap of mobula wings on the surface signals a feeding opportunity for the specialized ray-hunting orca. Like wolves separating sheep from the herd, the orcas isolate a single mobula. They then take turns slapping it from below with their powerful tail flukes, stunning the ray and preventing it from fleeing. Finally, they flip the ray upside down into a catatonic state known as tonic immobility, allowing the orca to easily devour its prey.
This reveals the often tragic duality of courtship in the natural world. The very displays intended to awe potential mates can also expose suitors to intense danger. But so strong is the evolutionary drive to reproduce that the mobula rays accept this mortal tradeoff.
Descending into Blackness: The Twilight and Midnight Zones
As sunlight dims, descending into the ocean’s twilight zone, life takes on even more alien forms. Here in the midwaters, 800 to 3300 feet down, creatures seem perpetually suspended in the gloaming dimness.
One of the largest animals found here is the elusive giant siphonophore, reaching lengths of up to 130 feet. Resembling a string of glowing light bulbs, this stinging predator is not actually one creature, but a chain of thousands of individual zooids working together. Each tiny zooid has a specialized role, be it swimming, reproducing, feeding or preying on passing animals.
Deeper still, down to about 13,000 feet is the midnight zone, where light totally disappears. Here the gulper eel is one of the strangest residents. With a mouth many times larger than its body, it can swallow prey nearly whole. Its flexible jaw and expandable stomach let it consume creatures much bigger than itself. To attract prey, it even uses a bioluminescent lure waving from its tail.
At this crushing depth, such adaptions are critical to survive in permanent darkness. But the challenges continue for those venturing even deeper.
The Ocean’s Plastic Predicament
Of all the dangers facing ocean life today, none is more pervasive than plastic pollution. Over 8 million metric tons of plastic waste enters the oceans each year. Plastic bags, bottles and microplastics broken down from larger debris now circulate through even the most remote waters. This slow-motion catastrophe is upending aquatic food chains.
Seabirds often mistake floating plastics for food. A staggering 90% of all seabirds now have plastic in their guts, with many dying of starvation and poisoning. The problem cascades down the food chain as prey species like fish consume microplastics, which then bioaccumulate in predator species. BP’s Deepwater Horizon oil spill showed how even one environmental disaster can impact ocean life for decades. Now the world faces a deluge of plastics every single year.
For some opportunistic creatures, however, the proliferation of plastics has offered novel chances for survival.
Hitching a Ride
The sedate Columbus crab is typically found clinging to the safety of floating mangrove roots and sea grasses along Central American coasts. Being awkward swimmers, their ability to disperse to new habitats is limited. However, they have discovered an ingenious new mode of travel by hitching rides on the backs of sea turtles.
In exchange for transport, they perform a housekeeping service by removing algae and parasitic barnacles from the turtle’s shell. This mutualistic relationship gives access to food scraps and protection, benefitting both species.
Today, plastics allow Columbus crabs to occupy habitats they otherwise could not reach. By latching onto drifting debris, from plastics to abandoned fishing gear, these resourceful crabs can now catch rides on ocean currents far from shore. Their adaptability provides a silver lining to the toxic problem of plastic pollution.
Tactics of Deception
For other species, the explosion of ocean plastics necessitates new tactics of deception. Male cuttlefish establish territories around underwater rocky reefs, finding crevices to conceal their eggs. But with plastic debris now littering the seafloor, cuttlefish face a dilemma.
Their first instinct is to avoid plastic entirely. However, rival males seeing vacant plastics quickly claim them as decoy spawning sites. This ensures competitors waste time guarding false sites, while they conceal their real eggs elsewhere.
Yet female cuttlefish have grown wise to the tactic. They ignore males associated with plastics, forcing deception-minded males to evolve yet more cunning tricks. This ever-escalating arms race reveals how ocean life is adapting not just to thrive, but to deceive in new plastic-dominated environments.
Thermal Havens Heat Up Competition
While shallow reefs and kelp forests teem with life, the deeper ocean is often presumed barren. But around hydrothermal vents on the seafloor, heat-loving bacteria form the basis of entire ecosystems. These oases attract vent endemic species uniquely adapted to extreme temperatures and toxic gases.
Octopuses typically brood their eggs for months on end to protect their young. The deep-sea pearl octopus is one dedicated mother. She seeks out thermal vents to lay her eggs, where the warmth accelerates their development. This allows her to reproduce faster than shallow water relatives.
But competition for these prime vent real estate is fierce. The octopuses have been witnessed wrenching each other off rocks, and squirting clouds of obscuring ink when vents are contested. Their normally solitary nature is overridden by the evolutionary drive to reproduce.
By 2016, sonar surveys detected hundreds of pearl octopuses aggregating around a vent system called The Cauldron. This represents the largest gathering of octopuses ever recorded on Earth. From barren darkness emerges an oasis of activity surrounding life-giving thermal energy from below.
Yet with many mining firms now eager to extract rare minerals from hydrothermal vents, these fragile ecosystems urgently require protection. The wondrous species found here have evolved over eons to exploit these extreme conditions. But they may not survive an onslaught of human activity in this last great frontier on Earth.
Opportunistic Survival in Human-Dominated Seas
Coastlines around the globe now bear the clear footprint of humanity. While pollution, habitat loss and overfishing threaten many aquatic species, some animals display opportunistic behavior to exploit human activities.
On the Pacific shores of Chile, South American sea lions have developed a behavior not documented in wild animals before. They have learned to steal fish directly from fishermen’s nets. After trawlers haul nets aboard, the sea lions move in, rocking small fishing boats back and forth. Eventually this tips fish onto the deck, allowing the clever sea lions to snatch an easy meal.
However, many bold sea lions fall victim to their own daring. Their narrow ribcages get wedged inside the fishing nets, where they become entangled and drown. Conservation groups now work to rescue trapped sea lions, minimizing unnecessary fatalities. But the intuitively intelligent mammals show no signs of halting their brazen fish burglaries.
This reveals how human dominance is forcing ocean species to make difficult tradeoffs for survival. Those flexible enough to seize opportunities may benefit. But interactions with human activities often prove perilous. How we manage and conserve marine habitats will determine the fate of species making gambles to survive in tomorrow’s oceans.
Giants of the Deep: Spectacle and Concern
In the open ocean, far from shore, the largest animal on Earth plies the waves. The blue whale reaches up to 100 feet long and 200 tons, equal to about 33 elephants. Despite its enormous size, many mysteries remain about its life in the pelagic realm.
Blue whales are solitary creatures, making them challenging to study. However new technologies have granted thrilling insights into their underwater behavior. Drones and critter-cams attached with suction cups reveal the giants’ acrobatics as they lunge through swarms of krill, mouths agape. The footage exposes a glimpse of their feeding, playing and courting, unseen by human eyes before.
Yet they also expose an unsettling reality. Many whales now bear scars from ship collisions, some nearly sheared in half yet still alive. Other whales become entangled in fishing lines for years, gear slowly slicing into their flesh. The new view into their world is both awe-inspiring and chilling.
While the days of commercial whaling have largely passed, human impacts on cetaceans continue. Ocean noise pollution interferes with their communication. Plastics fill their stomachs and taint their milk. Toxins accumulate in their blubber. Even emerging industries like deep sea mining and offshore wind now encroach into whale habitats.
Their persistence despite these threats is a testament to whale’s resilient spirit. But if they are to thrive for generations to come, we must take responsibility as stewards of the ocean to protect their world, as they have no choice but to share it with ours.
Conclusion: An Ocean of Wonder, An Ocean in Peril
The oceans of our blue planet contain endless mysteries, from sun-dappled shallows to the darkest depths where sunlight never reaches. Within this expansive underwater realm, Earth’s aquatic denizens employ ingenious adaptations to carve out their niches in a competitive and ever-changing environment.
Shapeshifting masters of camouflage patrol the coral reefs. Denizens of the deep have evolved bioluminescent lures and expandable jaws to survive in the crushing blackness. Opportunistic surfers latch onto fellow species for protection and transport, finding ways to exploit a sea of challenges. The vast diversity of life exhibited here underscores how much is yet to be discovered in Earth’s oceans.
But many newly uncovered marine behaviors and ecosystems are now critically threatened by human activities. Overfishing, plastic pollution, and climate change have proven catastrophic to fragile aquatic life. Mining, oil drilling, ocean noise, and rampant coastal development continue to industrialize formerly wild underwater frontiers.
As the expanse of unexplored habitat dwindles, so may species and survival strategies that evolved over eons be lost before we ever documented them. There is an urgent need for expanded marine reserves, pollution regulation, and sustainable fishing practices to prevent a silent extinction of the weird, wonderful, and yet unknown creatures beneath the waves. Our own fate is intertwined with the oceans and all they contain. Only by pursuing coexistence can we protect their future, and our own.
Frequently Asked Questions
How do pearl octopuses reproduce?
Pearl octopuses seek out thermal vents on the seafloor to brood eggs. The warm vents speed up egg development. In 2016, the largest gathering of octopuses was found congregating around a vent system.
Why do South American sea lions raid fishing nets?
Intelligent South American sea lions in Chile have learned to steal fish directly from fishermen’s nets by rocking their small boats. However, many bold sea lions get trapped in nets and drown.
What is a siphonophore?
The giant siphonophore is a deep sea predator reaching up to 130 feet long. It is a string of thousands of individual zooids, each with specialized functions like swimming, eating, and reproducing.
What are mobula rays known for?
Mobula rays are known for their spectacular vertical leaps, cartwheeling up to 2-6 meters out of the water during courtship. Their acrobatics help attract mates but also attract the attention of predatory orcas.
How do Columbus crabs hitch a ride on turtles?
Columbus crabs climb aboard sea turtles and eat algae and parasites on their shells. In return, the crabs gain free transport to new feeding areas. They now also use drifting plastic debris for catch rides on ocean currents.
What is the impact of plastic pollution on the ocean?
Over 8 million metric tons of plastic waste enter the oceans yearly. Plastics are consumed by marine life, leach toxins, and accumulate up the food chain. Seabirds often mistake plastics for food, with 90% now containing plastics in their guts.
How do clownfish protect themselves from lionfish?
Despite being small, clownfish have evolved an immunity to the venomous lionfish. They can fearlessly nip and chase away lionfishes that invade their territory. Their bright coloration also serves as a warning sign to lionfish.
