"You are about to enter the fourth dimension, time." "In nature, time is not always as we see it." "0n this journey, we explore nature´s hidden time warps." "Snails live in a time world where intervals less than a quarter of a second are too short for them to notice." "At a snail´s pace, minutes fly by." "Birds perceive smaller time intervals." "For a pigeon, the same moment passes more slowly than it does to us." "A fly has still quicker perception." "Its time world slows down even more." "(Siren blares )" "Although animals´ time perceptions vary, when facing an explosive event, the same seconds still count." "(Man, echoing) Stand by!" "Ten, nine, eight, seven, six, five, four, three, two, one," "Fire!" "Pigeons react fast enough to escape the flying debris." "A fly is even quicker off the mark." "But snails are too sluggish to even register the explosion." "It´s as if nothing had happened." "Mechanical clocks can help us keep track of the sun´s daily cycle." "But inside us and every organism, biological body clocks do the same." "But the same second is seen differently." "A fly´s basic eye reacts so fast, it stretches a second ten-fold." "Time-expanding vision matches a high- speed life." "(Woman screams in film )" "0ur complex vision works more slowly than the fly´s." "Cinema films exploit this by projecting 24 still frames each second." "We fuse the frames together to create the illusion of action." "Spiders share our slow speed perception." "Like us, they react to film images." "It has worked, hasn´t it?" "You´ll be all right now." "I know it´s workedI" "Flies don´t really see multiple images." "Instead, their vision is poorly defined." "But their eyes react so fast, they see each separate frame." "(Screaming broken up frame by frame )" "The eyes of the fly may stop-frame the film but it sees the movement that matters." "Its reflexes are ten times faster than ours as well." "Fast vision and reflexes are critical for a small, vulnerable insect." "(Very high-pitched) Help meI Please help meI" "PleaseI Please help meI" "Please help meI" "Spiders, with slow time perception, need traps to catch a fly." "Please help meI NoI Go awayI" "PleaseI NoI Please help meI PleaseI" "Go awayI Go awayI NoI noi" "No, no, noI noi" "No, no, no, noI noi" "Flying predators of insects need fast vision and fast reactions." "(Horn blares )" "The hobby needs to be fast too, especially to hunt dragonflies." "( # Rock on radio )" "In escape, fast reflexes are everything." "(Barking)" "The conflict between predators and prey is a conflict between time worlds." "The tortoise has a shell that protects it from predators living at a faster rate." "For a life spent serenely munching grass, quick reflexes aren´t needed." "There are so many varied perceptions, the same moment can be warped in many ways." "The hidden magic within a spray of water is seen only by those with the fastest perceptions, like the hobby." "Many fast actions have secrets hidden from our slow-reacting eyes." "The detail in this cascade would also pass the tortoise by." "Remarkably, an unexpected shower can make the tortoise´s perception even worse." "Cooled by the water, the tortoise sees even less detail." "Fast motion vanishes in a blur." "The cold slows down the eye´s visual chemicals until they no longer react quickly enough to register movement." "Dragonflies are also affected by falling temperatures that slow both vision and reaction times." "The warm-blooded hobby is unaffected." "It can now beat the dragonfly." "It´s no surprise that hobbies usually hunt dragonflies at the end of the day." "Heat affects the time perception of other predators too." "Like the tortoise, crocodiles are cold- blooded." "Their reflexes and visual reactions also vary with temperature." "While the crocodile is cold, wildebeest have little to fear." "Like the tortoise, the croc will see fast motion as a blur." "Its visual chemicals have the same problem forming an image." "By sunbathing, crocodiles accelerate the chemical reactions in their bodies." "And once the croc is up to speed, its prey materialises once more." "Reaction times also quicken to match its warm-blooded prey." "The prey´s vision reacts best to fast motion and can be fooled by slow movements." "The final strike pits reaction times against each other." "The great white shark is also a cold- blooded predator." "Its warm-blooded prey lives in cold water and so provides a challenge." "The seal´s vision and reflexes are unaffected by the cold." "The same applies to a more familiar mammal." "We also need to maintain a constant body temperature." "So our time perception, too, hardly varies." "Under stress, adrenaline can slow down the stopwatch in our brain creating the impression that time has stretched." "A surfer´s adrenaline rush may expand time but an encounter with a shark would warp it to the limit." "The great white hunts mainly by eye." "It can see in semi-darkness with its large, saucer-like eyes." "Prey can look surprisingly similar." "To avoid mistakes, the shark must maintain keen vision even in the cold." "Its solution is to shunt heat to muscles encircling the eyes." "The shark´s eye-warmers help check out a victim." "Super-heated vision makes the difference in the final attack." "Fortunately for surfers, sharks are choosy eaters." "They prefer their usual prey." "Great whites sometimes take people, but opportunities far exceed attacks." "Usually, surfers remain blissfully unaware that sharks are around." "As well as reflexes and visual speeds, an animal´s time world depends on its rate of living." "The universal guide to this metabolic rate is heartbeat." "The hummingbird´s heart beats 1,200 times each minute." "Its wings move so fast, to our eyes they almost vanish." "It shares the forest with a creature existing at the other end of the scale." "The sloth certainly lives up to its name." "It spends 80 per cent of its life asleep." "In a day, hummingbirds consume more fuel, size for size, than a jet fighter." "A sloth takes a month to digest a meal." "We would have to eat 45 kilos of sugar each day to match the hummingbird´s fuel consumption." "If we burnt energy at this bird´s rate, our large bodies would be unable to dissipate the heat." "0ur blood would boil four times over." "But even hummingbirds sometimes need to wind down." "A change in the weather causes problems." "Its energy needs can no longer be met." "Forced to shelter, it takes a tip from the sloth." "It drops its metabolism until the heart ticks 20 times slower." "(Thunderclap)" "At night, the sloth becomes active, but only relatively." "Its metabolic rate is still half that of other mammals of similar size." "The hummingbird enters a temporary state known as torpor." "Perpetual slothfulness is a way for the sloth to deal with tough forest leaves." "It gives time for digestion." "0ccasional torpor provides an opt-out clause to a high-speed life." "Danger periods just vanish." "(Flies buzzing)" "In Australia, other creatures have perfected the art of losing time." "In the summer, frilled lizards enter semi-torpor to escape the months when food is scarce." "They feed just once a week." "Predators such as black kites make the lizard´s foraging trips risky." "The lizard is only semi-active." "Its metabolism is operating two-thirds below normal." "To escape predators, it must switch into a higher gear." "It reacts in an unexpected way." "Trees provide a safe refuge both from predators and from the sun´s searing heat." "Dropping back into torpor, it reacts only to the sun´s movements, keeping itself in the shade." "It passes the summer in suspended animation, slowly waltzing to the sun´s rhythm." "There are far deeper states of suspended animation." "In cryonic suspension, bodies are actually frozen." "Some people dream that one day humans in this state can be revived." "0ther animals have already mastered the secrets of cryogenics." "In the spring thaw, they come back to life." "Young painted turtles of North America spend their first winter in cryonic suspension with up to half their body tissue turned to ice." "The wood frog also overwinters in a deep frozen state, and, like the turtle, uses sugars as antifreeze to protect its vital organs." "It thaws from the inside out, freeing the heart before defrosting the rest of the body." "While the animals were in suspension, their hearts had stopped as if they were dead." "The grey tree frog guarantees a heart- stopping winter by choosing an exposed site with a loose covering of leaves." "0nce defrosted, the animals are quick to exploit an active season of just six months." "Human cryonic suspension has so far been unsuccessful." "But occasionally, human corpses are exposed after thousands of years inside a glacier." "Although these bodies may never be revived, they do harbour the secrets of near- immortality." "Tucked into skin crevices, bacteria start to revive." "Some microbes have been resurrected after three million years in Siberian permafrost." "They are the true masters of time travel." "For ordinary mortals, life span depends mainly on size." "Elephant shrews rarely make their second birthday." "The elephant itself can live for 60 years, but at a pace of life 30 times slower than that of the elephant shrew." "Slowly ticking away the years, the elephant´s heart beats just 25 times a minute." "The heart of the elephant shrew whirs 800 times a minute." "At such different rates of living, they are hardly aware of each other´s existence." "0r the consequences of their actions." "The elephant shrew not only speeds through its time world 30 times faster than the elephant." "Its body processes are similarly accelerated." "Large, slow animals have longer lives than small, fast animals." "But they tend to have a similar number of heartbeats." "After 800 million, most will die." "Predators usually intervene long before the limits of life span are reached." "But predators face dangers too." "The stress of running ages their bodies." "Cycles of wear and repair take their toll." "Muscles can only be repaired so many times." "A lion faces its greatest stress once contact is made." "No lion runs unless it has to." "In the wild, a long life requires the conservation of body reserves." "Every jarring step potentially causes damage." "Many of us voluntarily subject ourselves to what lions try to avoid." "Although moderate exercise is good for us, even for the fit, a marathon is gruelling." "It can also be fun." "But damage results." "Some believe in a genetic cause of aging, others, that as we live, we create toxic by-products." "The evidence of nature points to the significance of wear and tear." "Birds fly from stressful situations." "This may help them live longer than land animals of a similar size." "A rat may match a pigeon in size, but lives just half as long." "Ravens at the Tower of London benefit from a protected life." "Like other captive animals, they often double their normal life span." "Some live for over 30 years." "Adult insects don´t even attempt repairs." "Bumblebees literally wear out." "The wing beats in their life are limited." "(Thunderclap)" "We can now live twice as long as other mammals of similar size." "But the rules of nature still affect us." "Cycles of damage and repair are finite when errors accumulate as cells are repaired." "A bumblebee expires after around four and a half million wing beats." "But before then, at three and a half, its aging body is vulnerable to predators." "In the wild, few animals reach old age." "Predators take out those weakened by accumulated damage." "We all live in different time worlds, but for many animals, life will end in a split second." "0n our next journey, Supernatural explores the near-paranormal powers of animals."