荒野世界 第 1 集：亞馬遜雨林

Nature is not a place to visit. It's our home. Nature is all that we see. Animals, insects disappearing into their surroundings. Using deceptions, disguises, lures. Nature is all that we hear. The call of an eagle. The hiss of ocean spray. The rumble of thunder. The doings of a cricket. Wonderful beauty of nature. The crucial, fragile affinity between animal life and their environment. All of this is World of the Wild. The Amazon. Spread over nine countries and five and a half million square kilometers. This is the world's largest rainforest and one of the most bio-device places on the planet. Teeming with life, much of which is still unknown to science. This episode examines some of the Amazon's most iconic inhabitants. The colossal anaconda. The easy-going sloth. The cold-blooded caiman. The hair-raising tarantula. And the mysterious Amazon River dolphin. In a place filled with legends. None have gripped the human imagination quite like the anaconda. With a stranglehold over the twisting morass of swamps, marshes and streams. That comprise the Amazonian wetlands. The anaconda family consists of five species. Among them, the largest snake in the world. While the gargantuan proportions of a green anaconda are subject to wild speculation. What is certain is that all anacondas are perfectly adapted to the waterways of their rainforest home. Relatively slow and cumbersome on the land. The anaconda utilizes the murky river system to travel effortlessly and to hunt with ruthless efficiency. Able to remain submerged for over ten minutes. They are expert hunters of the fish, turtles and caiman that inhabit the abundant waters of the Amazon. But that's not all. The entire jungle ecosystem is dependent on its waterways. And here, the waterways give the anaconda license to rule. High-set eyes and nostrils allow it to remain almost entirely hidden in the water. While laying in wait for the land-based prey. Anacondas will eat anything they can overpower. And for a snake this big, few in the Amazon are safe. Like all reptiles, anacondas are ectothermic. Obtaining their body heat from their environment. The Amazon rainforest's year-round average temperature of 27 degrees Celsius makes this paradise for big snakes. Beneath the thick jungle canopy of the Amazon, darkness comes quickly. But the anaconda has adapted to hunt without light. Specialized sense organs around the lips detect body heat. The flickering forked tongue takes chemical cues from the air. And sensitive skin detects sounds and vibrations on land and in water. Latching onto its prey with hundreds of razor-sharp teeth, it's not the anaconda's bite that kills. A non-venomous snake, the anaconda employs its long muscular body to coil around its jungle prey and patiently suffocate them. Meals are swallowed whole. Disengaging the lower jaw, the snake can stretch its mouth around food far bigger than its head. With a menu as wide as its gape, the anaconda preys on all that the Amazon has to offer. A top order predator of the Amazon, the greatest threat to the deadly anaconda is from man. Prized for their legendary status, as well as their magnificent skin, the surprisingly shy and elusive nature of these snakes has so far kept them safe, allowing the legend to continue to grow. From the waters to the trees, the Amazon rainforest is a densely interwoven ecosystem, and one humble creature is the true embodiment of this. Sloths are the most prevalent tree-dwelling mammals in South America. They are also the least conspicuous. Concealed within the rainforest canopy, sloths display a distinctive preference for the widely distributed Cecropia tree, also known as the sloth tree. Sloths coexist as one with the jungle, to the point where their coat is a jungle in microcosm. Considered walking ecosystems, sloths' bodies are covered in thick coats that harbor their own animal and plant life. With the Amazon's almost daily rainfall and high humidity, the sloth provides a hairy habitat for moisture-seeking moths, beetles, cockroaches, and a specialized form of algae. Found nowhere else in the world, this host-specific microorganism has evolved with the sloth and is passed on to infants as they cling to their mother's fur. While the algae aids in camouflage, this symbiotic relationship also extends to the sloth's diet. As folivores, the sloth's main food source is leaves, which are not only tough to digest, but provide little energy. By growing and consuming their own algae gardens, sloths are able to boost their nutritionally poor diet. But even with a boost to their diets, sloths carry around 20% less muscle tissue than most mammals. Lacking the ability to make a quick getaway, sloths are at the mercy of Amazon's many predators, predators like the jaguar. An expert climber, sloths can do little to defend themselves from this feline foe, but little is exactly what they do. Inactive for great parts of the day, sloths only move when necessary, hence the name, sloth. Often remaining in the same tree for years, when sloths do move, they are quiet, gentle, and slow, minimizing disturbance to the foliage, and never calling attention to themselves. In this way, a lack of speed is advantageous, the sloth's economy of movement leaving predators completely oblivious to their presence. In their own effortless style, sloths are masters of the Amazon, but their success in the rainforest has come at a cost, with sloths unable to survive outside their specific habitat, as the embodiment of the interconnectivity of the jungle to preserve the Amazon is to preserve the sloth. The vast expanse of the jungle, its rainforest and river systems, its mangroves and marshes, has fostered a diversity of life, and a diversity of caiman. Members of the ancient order of crocodilians, caiman are another apex predator of the Amazon's waterways. With six species, from the diminutive dwarf caiman to the mighty 5-meter long black caiman, all are found in the Amazon. Once covering most of South America, the Amazon rainforest is over 55 million years old. Perfectly in tune with this ancient environment, the caiman's lineage is even more prehistoric, and they are considered among the most perfectly adapted creatures on the planet. Propelling themselves through the water with their thick powerful tails and webbed feet, caiman are excellent swimmers, with dominion over the Amazon's rivers and lakes. Hunting primarily by sight, their large eyes have vertical pupils, allowing for excellent night vision. An additional transparent eyelid grants protection and clearer vision while stalking beneath the surface of the Amazon's waterways. Snatching prey in their powerful toothy jaws, they are opportunistic predators, taking advantage of whatever food source is most abundant. With a wide diet including fish,amphibians, insects and snails, as well as other reptiles and large mammals, for caiman,the Amazon is a smorgasbord. But the Amazon also knows privation. During the annual dry season, the waters recede and ecosystems once connected by floodplains and streams become cut off, reducing the caiman's hunting grounds. But caiman are equipped to wait the dry season out, able to go for months without food. Conserving energy, they reduce their hunting activity. Being cold-blooded, no energy is wasted on producing heat, instead drawing it from the environment. When times get really tough, caimans can resort to cannibalism. Climate change poses a more existential threat, the sex of crocodilians is determined by temperature while incubating in their eggs. When held at around 30 degrees Celsius, hatchlings tend to be female, just 4 degrees higher and the hatchlings are predominantly male. With global warming, scientists are concerned about the possibility of an overpopulation of male caiman. Will this ancient species be able to adapt to a rapidly changing world? Caiman have bounced back before. Once hunted to near extinction for their valuable leather hide, this led to an imbalance in the Amazon ecosystem. Strict anti-hunting laws and protected habitats have made the caiman a conservation success story in the Amazon. And their return to the top of the food chain has played an important role in maintaining the balance of the Amazon's fragile ecosystem. In the dark of the Amazon undergrowth, a whole other world exists. With sunlight blocked out by the thick rainforest canopy above, this shady,humid environment is littered with decomposing plant and animal matter, returning nutrients to the jungle ecosystem. But the rainforest floor is also home to a surprising abundance of life. A staggering 90% of all the creatures that live in the Amazon are arthropods, a group of invertebrates with external skeletons. Arthropods include insects, centipedes, scorpions and spiders. With an estimated 3,600 species of spider in the Amazon, one species is arachnophobia personified, the tarantula. Inhabiting the planet since the age of the dinosaurs, there are over 800 species of tarantula spread over most of the world. Tarantulas are the biggest of the spiders and the biggest of the big are found in the Amazon. Here tarantulas can grow to the size of dinner plates. Occupying underground burrows or tree hollows, unlike many spiders, tarantulas do not use their web to catch prey, preferring instead to ambush them. Laying in wait in their burrow entrances, tarantulas are coated in sensitive hair that helps them detect prey called seta. These fine sensory organs are used to pick up on vibration, identify chemical signatures akin to smell and possibly even detect sound. This coating of seta allows tarantulas to determine the location and size of approaching quarry before they see it. The typical tarantula diet consists mainly of insects, frogs, small lizards and even mice. The enhanced proportions of Amazonian tarantulas means that they are capable of tackling larger preys. When the victim is within range, the tarantula launches its attack, using its legs to grab hold of its quarry and paralyzing it with venom. Once the victim is dead, tarantulas administer an injection of digestive enzymes, liquefying their meals and sucking them up through straw-like mouths. Despite the tarantulas' fearsome appearance, they pose little threat to man. Man, on the other hand, poses a threat to tarantulas through habitat destruction and the pet trade. Fortunately, in the case of the Amazon, all indications are that the tarantula population is continuing to thrive, draining 40% of South America each year the waters of the Amazon River burst their banks, transforming lowland jungles into enormous floodplains. Amazon River Dolphins, also known as Boto Dolphins, are the largest freshwater dolphin in the world and a mystery of the animal kingdom. While much remains unknown about these unique creatures, they are the unlikely specialists of the Amazon River. Boto's live their entire lives in the turbid waters of the Amazon and its tributaries, leading to a set of very specific adaptations. The Boto's long, broad flippers and low dorsal fin grant it extreme maneuverability even in shallow water. Unfused neck vertebrae allow river dolphins to turn their heads 180 degrees to either side, a vital adaptation in navigating a choked maze of submerged obstacles. Sweeping their heads from side to side, the Boto's employ an advanced echolocation system to navigate and to locate prey with pinpoint accuracy. With small eyes, there is uncertainty as to how well Boto's can see. But hunting fish, turtles and crustaceans in the dark, muddy waters of the Amazon, it is certain that they do not rely on eyesight. An enlarged hump on their heads helps focus their sonar and an elongated snout enables a dolphin to extract food from hiding places in hollow logs or submerged thickets of vegetation. However, these specialized adaptations have come at a cost. Speed. River dolphins are far slower than their distant relatives in the oceans, but being slow does not disadvantage the Boto because within the Amazon, it has no natural predators. No predators, that is, except for man. Traditionally, Amazonian tribes protected the Boto, believing them to be semi-divine beings capable of shape-shifting into human form. Today, industry and fishing threaten the Boto's habitat and the food source they depend on to survive. Climate change is another threat, placing an additional strain on fish stocks and bringing unpredictability to the Amazon's annual floods. Unable to survive in salt water, the Amazon river dolphin has nowhere else to go With the population of this mysterious species difficult to determine, the only sure way of protecting them is the preservation of the Amazon's precious river ecosystems. Rainforests are believed to contain more than half of all the plant and animal species on Earth, as well as countless others waiting to be discovered. In the case of the Amazon, we have seen the anaconda, the sloth, the caiman, the tarantula and the Boto dolphin. Yet the influence of the Amazon stretches far beyond its borders. Considered the lungs of the planet, it produces around 20% of the world's oxygen and stops greenhouse gases from entering the atmosphere. But at current rates of deforestation, in as little as 50 years, the vast wilderness of the Amazon may no longer exist. Conservation efforts have been successful in reducing deforestation, but the Amazon is still shrinking. The planet needs its lungs, now more than ever. And greater protection is required to sustain the Amazon in order for it to continue sustaining us.