Incredible Scenes of Wild Animals Battling to Survive ｜ BBC Earth

Northern Australia has the highest tides in the tropics, which expose vast areas of shoreline. And here lives a truly extraordinary species of octopus. Octopuses are marine animals. They live and breathe underwater. At low tide, most octopuses will be imprisoned in their rocky pools. But this is no ordinary octopus. It's the only one specially adapted to walk on land. It pulls itself along using the hundreds of tiny suckers that line its arms. Hunting for crabs, it walks from pool to pool. Apart from a rather startled fish. This one is empty. So, the octopus moves on. Pool may seem like a safe refuge. But the octopus's suckers enable it to move just as stealthily in water as out of it. Nowhere is safe when this octopus is around. Christmas Island in the Indian Ocean. For millions of years, this remote speck of land has been ruled by crabs. Their ancestors came from the sea, but most have now adopted a land-based existence. Given there are so many of them, they get along relatively harmoniously. They're the gardeners and caretakers of a tiny crab utopia. Once a year, they must all return to the sea to breed, and the March of the Red Crabs is one of the greatest natural spectacles on Earth. There are 50 million of them. It's an event that has brought the island worldwide fame. But in recent years, millions of red crabs haven't managed to reach the sea. An invader has occupied this island. Yellow crazy ants. They escaped from visiting ships, and with no predators to control them, they have now created vast supercolonies in the forest. When migrating red crabs march into their territory, the ants attack, squirting acid into the crabs' eyes and mouths. The crabs have no defence. Blinded and confused, they're doomed. Humans brought these ant invaders here, and now humans are having to control them. Isolated communities may evolve for millions of years in relative peace, but when new challenges arrive, they can struggle to cope. Of all the species that have become extinct in recent years, around 80% have been islanders. Hunting is only possible for three hours around low tide when the mud banks are exposed. Razor-sharp oysters cover much of the shore. Beaching here could be lethal. The hunters need to find a stretch of shoreline with just the right slope. Too level, and the dolphins risk stranding. Too steep, and they can't force their prey from the water. Working as a team, the dolphins surround the fish, driving them towards the shore. Perfect synchrony, the dolphins create a bow wave. It carries their prey onto the muddy banks. Other fish-eaters profit from their daring. Hermes and Gulls follow every hunt. To get to the fish first, the dolphins drive themselves high up the bank. But if they go too far, they risk stranding. To prevent fish escaping between them, the dolphins all beach themselves on the same side. Always the right. But this has a cost. Each time they grab a fish, they also take in a mouthful of mud. The grit gradually wears down their teeth. But on one side only. In time, these teeth get so worn down that older dolphins can no longer hunt like this and must find other ways to catch fish. Sixty million tonnes of snow now blanket this herd's territory. Pushing through deep snow is exhausting work, and the bison are now slowly starving. Just keeping warm saps huge amounts of energy. Their thick coats can insulate them down to minus 30 Celsius. It's now minus 40. The only thing that will keep them alive is buried beneath a metre of snow. And that's a problem shared with a surprising neighbour. The food the fox seeks is also deep beneath the snow. The survival of both creatures depends on getting through to the ground. For the bison, it will be a matter of brute strength. Massive neck muscles enable them to shovel five tonnes of snow a day. Their lightweight neighbour needs more precision. The bison have reached their goal. A mouthful of withered grass. And where the bison have dug, the fox now spots an opportunity. Every footstep counts, but he mustn't break through. Yet, he listens carefully to pinpoint his target. It's moving. A vole. Small, but a hundred times more nutritious than a mouthful of dried grass. To get through the winter on these prairies, sometimes brain beats brawn. And leopards are the most versatile of all the big cats, adept at finding cover in the most unpromising places. The steep walls of the gully are now her cover for an ambush. The male puku is close enough, but he's too big to tackle. She needs to slip past him without being seen. If he spots her, he'll blow her cover. Slowly does it. To succeed here, she needs to find prey grazing close to the edge. Or better still, in the gully itself. Frustration. Success would have staved off hunger for a week. But while there's prey around, there's hope. Peeking over the top is a risk, but it's the quickest way to find a new target. A burst of speed of 65 kilometres an hour, and it's all over in less than six seconds. Except, it isn't. Dazed and disorientated, the impala makes a miraculous escape. The struggle to survive in our green seas can have far-reaching consequences. Once a year, one particular meadow in Australia is transformed. Around the first full moon of winter, an army materialises. Spider crabs. For the past year, they've been feeding in deeper waters. Now, they march across the seagrass plains. Hundreds of thousands of them. They clamber over one another, creating great mounds nearly a hundred metres long. They're not seeking mates, neither are they laying eggs. They have come here in order to grow. Like all crabs, their bodies are enclosed in a hard, unexpandable shell. So, to grow, they have to break out of it. And that allows the soft one that has developed belief to expand. It will take days for the new shell to harden. Its legs are so limp that they won't work properly. The crab is unprotected and in great danger. A smooth stingray. It's huge, about four metres long. It wants a soft, freshly-molted crab that will be easier to eat. The crabs try to stick together. Disturbed by the ray, they're scattering. A newly-molted crab is too weak to keep up with the crowd. The safest place is right in the middle of the pile. That is why they have all assembled here. There is safety in numbers. But the vast majority of the crabs escape. And within the next few days, they will be ready to return to the depths and resume their lonely wanderings in search of food. This is no graveyard, but the triumph of 100,000 crabs successfully molted. At this time of year, polar bears, on average, succeed only once in 20 hunts. If the hunter is skinny, like this one, that may not be often enough. All she can do is keep trying. To prevent her scent betraying her, she makes a wide sweep to get downwind of the seal. Getting close, she's now right behind the seal. Incredibly, she caught the seal underwater. It's only small, but even so, its blubber alone will contain 100,000 calories, enough to sustain this bear for a week. And in that time, she might even catch another. But this can't go on forever. As summer continues, temperatures are rising. Each hunt requires more energy, draining the bears of their reserves. It's July in the deserts of Nevada in the western United States, the hottest time of the year. Bands of wild horses, mustang, are converging on one of the last remaining waterholes around. Now, water not only offers them the chance to drink, it can also bring power. If a stallion can control access to water, he will have secured mating rights to the entire herd. So, stallions try to dominate these pools, fighting off rivals who venture too close. A stranger. He's traveled 15 kilometers to be here because the pools where he's come from have already dried up. With him come his females. If he can't provide them with water, they will leave him for the white stallion, who already dominates this pool. So, he will have to fight. There is everything to lose. A broken leg or a shattered jaw would mean a slow and painful death. A missed kick, and it's all over. The new arrival has won. And his prize is more than just a chance to drink. He has provided for his herd, and in the process, stolen his rival's females. The white stallion's rule is over. Desert life is not only shaped by the scarcity of water, but also by the relentless power of the sun. Lions will normally avoid hunting in such heat. But they're also opportunists. The lions will need to bring him down quickly before they overheat. Even away from the herd, a bull is a formidable opponent. It could gore and kill a lion. Close to overheating, they finally succeed in bringing him to the ground. But the massive bull is not giving up. Against the odds and the full weight of the lions, he regains his feet. And it is now that the tables turn. Lions are exhausted. After a 20-minute struggle, only the bull has the energy to finish the fight. In such exposed and extreme conditions, the challenge for predators and their prey is at its most intense. To see a tiger hunting bull is extremely rare. To capture it on camera is virtually impossible. But Bagani takes me by surprise. She's taking a terrible risk. But as I watch, I see a new Bagani, a changed tiger. This one is the master hunter I knew at Rantambol. She carefully moves her tail round the grass stems to ensure she makes no noise. Surely, nothing can stop her now. The fact that Bagani leaves her kill shows her confidence. There is no one who would dare take it. This really is her territory now. It's called Darwin's bark spider, and the female has a remarkable strategy. Like a real-life spider woman, she sprays strands of silk in one long, continuous flow. The threads fan out like a sail and drift on air currents blowing across the water. Every few seconds, she crimps the strands together to stop them spreading too widely. The breeze will do the rest, blowing the threads into a single line and a 25-metre bridge. Now, she must reinforce her bridge because her web will hang from it. But there's something bouncing the line at the other end. Another Darwin's spider is trying to take advantage of her hard work. She must deal with the intruder head-on. The cut line is an inconvenience, but no more than that. With hooks on the tips of each leg, she gathers in the thread. It won't go to waste, as she'll eat it later. When it's all reeled in, she sprays again. Out streams another 25-metre bridging line. How a spider no bigger than a thumbnail can produce so much silk so quickly has baffled scientists. And it's no ordinary silk. It's the toughest natural fibre on the planet, tougher than steel. And it needs to be tough to span the wide river. With the bridge taut and the ground anchor in place, it's time to construct her trap. These spiders can build the world's largest orb webs, up to two metres wide. A few hours from the first spray of bridging line, the job is done. Now, her strategy is simple. Sit and wait. And there's one final bout of silk production, shrink-wrapping her food for later. The Nile crocodile, a creature older than Africa itself. Its hunting skills honed over 200 million years. Using extreme stealth, the crocodile needs to get within a metre of its prey. Desperate to drink, the buffalo seem blind to the danger. Just too much for a croc out of water. But there'll be another chance. The army ant. This may look like a ball of a million individuals, but make no mistake, the colony acts as one. A superorganism with a sensory system of two million antennae. A skeleton made from the living bodies of workers. A defence system of soldier ants, ready to act at any sign of danger. A digestive system, processing piles of food deep inside. Even a coordinated system for dealing with all the waste. These are insects that, by working together, transcend individual size. The colony can search the entire jungle and flush out its wildlife. Each day, it sends out a silent probe into the forest, in quest of food. It doesn't use scouts like other ants. Instead, a vast search party pushes into virgin territory, seeking out the signs of anything alive. They spread out along a ten-metre front, sweeping across the forest floor. To find prey, the ants must first touch it. The irony is that this, the most successful hide-and-seek player in the forest, is almost completely blind. It distinguishes the living only by their movement. As long as an animal remains still, it is safe. But the slightest twitch will give it away. Within seconds, the prey is pinned down. Within minutes, it's torn apart at its joints. The more the prey struggles, the more the ants engage. Right across the raid front, prey of all sizes are driven from their hiding places. Even wasps must abandon their homes when the ants arrive. Everything alive in the path of the raiders, overwhelmed by sheer numbers. The differences are only in the animals themselves, their strategies and their settings. In the sky, there's no place for a stalking predator to hide. So, for the element of surprise, the peregrine falcon has to resort to sheer speed. In a dive, it's the fastest bird in the world. So fast, it's breathtaking. It stalks by flying high and relying on eyes that are as good as telescopes. The fat, slow-looking pigeon might seem to be doomed, but it evolved as peregrines evolved and is equipped to watch for them. Eyes on the side of its head enable the pigeon to forage for seed and scan the sky at the same time. It spies the peregrine, and once it's in the air, it becomes a racer. Lightness, streamlining, speed. The pigeon, strength, endurance, enough speed, and a head start. The peregrine is more manoeuvrable. The pigeon has a wider field of vision, though, and plenty of manoeuvres of its own. It's also flying for its life. This time, the pigeon outflies its pursuer. This peregrine is still young and just learning that speed by itself isn't always enough. It must race its game. Food is so hard to find this far north that a wolf pack must search hundreds of square kilometres if it's to be successful. And success means raising the next generation. To do that here, the wolves must work together. So, the young are raised not only by their parents, but by their aunts and uncles as well. Together, they try to ensure that each pup reaches near adult size before the snow returns. A growing pup needs more than just a few leverets. The wolves need bigger prey, and to catch that... ...they must hunt as a pack. Adult hares may be easy to spot, but they're far from easy to catch. They run at 60 kilometres an hour. To catch one, the wolves work as a team. One of them gets close enough to bite the hare's tail. But a hare can change direction in an instant. If it can continue to sidestep and jink, it may ultimately outlast them. Finally, it gets away. For the next hare, the whole pack gives chase. Numbers count. The lead wolves keep up the pace. Others run on either side, so the hare can't change direction. A tiny meal for the whole pack.