- The islands that lie between Asia and Australia were forged by fire. Their great wealth of plants and animals the result of a violent birth. - (HOOTS) But there is a parallel world, where the moon holds sway. Here, fish live inside trees... and run away from water. Insects light up the darkest of nights. And crabs dance. The power of the moon is strongest along the coast and in the shallow seas. Here, the moon reigns over her shadowy subjects. (ETHEREAL MUSIC, WOMAN VOCALISES) Captions by Julie Taylor. Captions were made with the support of NZ On Air. www.able.co.nz Copyright Able 2021 (ETHEREAL MUSIC, WOMAN VOCALISES) - Every day, the moon pulls on the water of the oceans, creating the tides. Over millions of years, the plants and animals of the coast have evolved ways to survive the dramatic change from saltwater to dry land. The tide floods vast areas of the coastal mangrove forest. This is a world the moves to the rhythm of the moon. In places, saltwater infiltrates kilometres inland to the traditional sleeping trees of proboscis monkeys. (WATER LAPS SOFTLY) These monkeys of the moon must wait for the tide to fall before they can reach their favourite food. So they're in no hurry. (HAUNTING MUSIC, WOMAN VOCALISES) The moon recedes and slowly draws the waters from the mangroves. Fish are forced to leave, for within hours, water will be replaced by air. The morning's stretching and scratching over, the monkeys set off through the tops of the flooded forest. (BRANCHES RUSTLE) In places, the forest stretches for kilometres. The monkeys face a long journey, for their goal is the distant shoreline. Their forest may have as many as a dozen different kind of mangrove tree. Each species has had to find ways to survive in an extreme environment that would kill other trees. Rhizophora trunk doesn't reach the ground. Instead, a web of giant roots projects outwards to support the tree in the soft, gooey mud. That mud smells of rotten eggs and lacks oxygen. Avicennia grows strange pencil roots that stick up from the mud. The pores breathe in air to stop the buried roots suffocating. Only by extraordinary adaptations like these can the trees survive in this strange, amphibious world. All the fish are leaving with the tide, except, that is for these gobies. Just 2cm in length, they've found a surprising way of staying in the mangroves. Some tree trunks and logs are riddled with tunnels dug by a kind of sea snail. As the water level falls, the fish swim into the holes. The tide drops further, exposing the fallen tree trunk. But the gobies are safe in the water-filled passageways. Most fish may have left, but the forest is not deserted for long. A new cohort of air-breathing creatures is waiting for the tide to retreat. At the feet of the mangroves live tiny fiddler crabs that measure less than 3cm. They are dwarfed by the leaves and pencil roots of the mangrove trees. Like the trees, they've evolved over millions of years. There may be as many as 10 species on one mudflat,... each with its own particular way to survive between the tides. This red fiddler crab claims the top of the tide. He feeds at a leisurely pace, for the water will not return here for 10 hours. But to breathe, he must keep his gills wet. So he regularly returns to his burrow and his subterranean pool of water. But a tiny crab must always be alert for danger. Predators enter this ambiguous place... that is both sea and land. This skink is a hunter of crabs. The crabs are quick and stay close to their burrows. But if the skink sneaks close enough,... it can outrun them. High above the mud, the monkeys of the moon keep pace with the falling tide. (BRANCHES RUSTLE) They're after something tasty to eat. But it'll be hours before they reach their goal. So, for now, the monkeys chew on dry mangrove leaves. The most striking thing about an adult male is his spectacular schnozzle ` nothing to do with nutrition, but a lot to do with sex, for female proboscis prefer nasally well-endowed males. We have no idea why. The other obvious feature is the huge belly. Proboscis have two stomachs to help them break down the unpalatable fibrous leaves. The reason that some mangrove leaves taste bad is that they're full of saltwater that would kill other plants. But mangroves have evolved ways of surviving. (SOFT, WONDROUS MUSIC) Another kind of mangrove stores the salt in its old yellow leaves. It then discards them, ridding itself of the toxic salt. Extreme ways to survive between the moon-driven tides. The water is leaving the mangroves, and the proboscis follow the tide. (ETHEREAL MUSIC) (WOMAN VOCALISES) The tide left the fallen tree trunk behind long ago, but for now, water remains in the tunnels. And the gobies push ever further into the labyrinth. They're not completely safe even here, deep inside the log. A miniature octopus, its body less than 3cm, waits patiently. While the fish try to avoid the octopus in the dark of the fallen tree trunk, the moon continues to move away. At last, the tide departs the strange, shadowy forest and reaches the coast. As the mudflats are exposed, more strange creatures of the moon emerge. Blue-spotted mudskippers spend half their lives underwater in burrows in the mud. (INSECT BUZZES) (BUZZING STOPS) (BUZZING RESUMES) These bizarre fish spend the other half of their lives out of water, grazing microscopic algae on the muddy plains. They defend their patch of mud and microbes by a display of banner-like fins and bouts of jousting. (WATER SLOSHES) (WATER SLOSHES) The retreating tide has uncovered the mudskippers' beach. The monkeys can walk the final metres to their goal ` a tree that grows along the beach. And this is what they've travelled kilometres for ` the flowers of the sea hibiscus. After the dry leaves of the mangroves, the monkeys relish the sweet-tasting flowers. - (CALLS) - While the adults are tucking in, the youngsters take the opportunity to play. (BOTH SCREECH) - (CALLS) - The moon is far away, close to the horizon. As it recedes, the tide uncovers more and more fiddler crabs. They feed by sifting the fine sediments for tiny plants and animals. The female has a major advantage over males. She has two claws to feed her whirring mouth parts. The male, in contrast, has only one feeding claw. The other is monstrously enlarged, so males can only feed at half the speed of the females. They are handicapped by a claw that weighs half their bodyweight. Why have such an impediment? One function is to signal their possession of a small patch of beach, for their lives depend on the food in the mud around their burrows. Each species of crab has a different display of ownership, different gestures, claw size and colour. The displays are aimed at any intruder. It doesn't matter the species or size. In the majority of cases, a display is enough to resolve a conflict. But sometimes, the dispute escalates. Weapons are prepared,... warnings sent out. On guard... and fight. While these combative crabs fight, the tide slides further down the beach, uncovering yet more strange subjects of the moon. This species of fiddler crab lives in sticky clay and specialises in sifting the find particles. Even closer to the low water mark lives a fiddler crab with the most extreme tidal life. They have as little as two hours before the tide returns, so they feed twice as fast as the red crabs that live back amongst the mangroves. All these different kinds of crabs have evolved over millions of years under the tropical moon. The fiddler crabs are in such numbers that they attract a bearded pig. - (GRUNTS) - The tiny crabs are no more than a snack to the pig, but they must taste good for the pig to risk walking out on the soft mud. And it's not alone. Unlike the pig, they have delicate fingers so have to watch out for the crabs claws. - (SCREECHES) - For the crabs, it's not just the attentions of pig and monkey they must survive; the fierce sun can make the midday hours unbearable. Temperatures can reach 40 degrees Celsius. While the crabs suffer, the tiny gobies stay cool inside the fallen tree trunk. But the water is draining out. Soon the tunnels will be dry. It'll be hours before the sea returns to the fallen trunk. All the creatures of the moon are waiting for the tide to turn. As the Earth rotates, the moon pulls up the seas, and this bulge of water moves across the face of the Earth. (ETHEREAL MUSIC, WOMAN VOCALISES) At last, the tide changes direction. (MUSIC, VOCALISING CONTINUES) (MUSIC, VOCALISING CONTINUES) Fiddler crabs evolved to breathe air, but now they must prepare to spend time underwater. The crabs closest to the low tide are the first to disappear. They must keep very still. Water has little oxygen compared to air, and so they struggle to breathe. It'll be 10 long hours before the tide releases them from their watery prison. As the water forces its way back up the beach, the many different crabs disappear one after another. There's just enough time for a last display of ownership before the blue-spotted mudskippers disappear down their burrows. Another kind of mudskipper is more of a nomad. They were feeding on the low tide. Now they make the long march back up the beach, racing the tides, trying to keep out of the water. The tide slithers back towards the mangroves. The monkeys of the moon are forced to leave their sweet-tasting flowers. As soon as they are safely back in the trees, the youngsters start rumpusing again. But in doing so, they disturb a nest of weaver ants. These aggressive ants rush out to confront the commotion. As they search, they attack everything they encounter. (JARRING MUSIC) The dismembered body parts are taken back to the nest to feed their grubs. (ETHEREAL MUSIC, WOMAN VOCALISES) The tide pushes the nomadic mudskippers into the mangrove forest. To avoid the advancing water, they climb into the trees. Here, they will perch, safe from predatory fish, until the water starts to drop and they once again can become nomads of the moon-driven tides. The water pushes on into the mangroves and flows back into the tunnels of the fallen tree trunk. The tiny gobies stir. Amazingly, these tough little fish have survived six hours out of water. They leave the safety of their labyrinth to feed on the microscopic plankton carried on the tide. The other fish that were driven out hours ago now return on the rising waters. The strength of the tropical sun begins to fade. But the power of the moon remains,... undiminished day or night. 12 hours and 25 minutes after it left, the saltwater returns to its highest point. A cycle of tides is complete. Strange fish swim in on the high tide. Weaver ants patrol the mangrove branches looking for prey. But now the hunters are the hunted. The high water brings the ants within range. These archer fish estimate the distance, and then shoot. Though, at first, some fine-tuning is required. The fish correct for the effect of gravity on their watery missiles. They can shoot a bullet of water powerful enough to dislodge the most tenacious grip. The fish alter the speed of the stream of liquid as they spit. So, later, faster water catches up with slower, creating a silvery bullet. (PLOP!) (WOMAN VOCALISES) The saltwater retreats from the dark forest, leaving small, isolated pools. Any fish trapped in the puddles are in great danger. A fishing owl. Its sharp vision pierces the gloom of the forest. Its talons are huge; the skin on its feet hard and ridged ` all adaptations for grasping slippery fish. (WATER LAPS SOFTLY) The influence of the moon is felt wherever there is water. (ETHEREAL MUSIC, WOMAN VOCALISES) The tides have as much impact on the seas as they do on the mangroves and beaches. Every day, tidal currents convey nutrient-rich waters. This, in turn, produces a profusion of plankton. These tiny creatures are at the mercy of the tides and are the prey of the largest fish in the world. Whale sharks can grow over 10m long and weigh 20 tons. (ETHEREAL MUSIC, VOCALISING CONTINUES) They feed by forcing plankton-rich water into their huge mouths. In places, there is so much food in these seas that whale sharks can remain here all year, simply swimming from one cloud of plankton to another. It's the plankton that supports a wealth of life amongst the countless islands that lie between Asia and Australia. They're surrounded by warm, shallow water that is ideal for the growth of coral. These are the richest reefs in the world. There are over 1400 species of fish, more than the whole of the North Atlantic. And many ` anthias, damsels and fusiliers ` feed directly on the plankton. It's not just small fish that join the feast. Oceanic and reef manta rays filter the plankton as they fly through the water on 7m wings. The giants visit the reef for a very specific reason. As the ray hovers, moon wrasse race up from the reef to pick off parasites and nibble at old or damaged skin. The reef is a kind of maintenance station, where the mysterious giants can stop and be cleaned and serviced before they resume their long-distance flights through the plankton-rich seas. It takes a lot of fish to clean a manta ray. And in trying to help, one or two fish can get a little too intimate. The moon-driven tides bring the plankton that supports fish big and small and, in places, in vast numbers. The anchovies attract hunters ` swifter, sleeker mobula rays. These rays hunt in packs, herding the small fish and pressing them against the reef. (WATER RUSHES) (WATER BURBLES) (WATER RUSHES) Once the anchovies are confined, the rays attack. The anchovies are seized as the rays plunge through the shoals. After the frenzy of attacks, the anchovies regroup, and the sinister shepherding starts all over again. As the moon goes through her monthly phases, so the tides wax and wane. (ETHEREAL MUSIC, WOMAN VOCALISES) They are strongest at the full and new moon. The phase of the moon affects all her subjects, both on the reefs and in the coastal forests. The profound dark of the new moon enhances the display of fireflies in the mangrove trees. The males synchronously flash their desire. It was thought that the males were cooperating to make a bigger, better display. But why would they do such a thing? They are competing with each other. It turns out that the females have a preference for the male that displays first. In trying to make the initial flash, all the males end up displaying in near-perfect synchrony. The effect is mesmeric. The fireflies are miniscule ` less than 6mm ` yet they're so bright they can be seen from hundreds of metres away. (ETHEREAL MUSIC, WOMAN VOCALISES SOFTLY) (MUSIC, VOCALISING CONTINUES) Two weeks later, the moon is full and the tide is once again at its highest. The bright moonlight has a dramatic effect on many fish. All over the reef, bohar snappers are congregating. They swim towards a place where the tidal current is especially strong. The fish form ever-tighter shoals and move up towards the surface. There, they spawn in a mass orgiastic event. Eggs and sperm are expelled and mix in the water as they're swept away by the current. Black snappers race in to eat the eggs. But the sheer number of bohar snappers means most eggs will drift safely away from the reef and its many hungry mouths. They will join the plankton, and after a few months, some will return to the reef as baby fish. (ETHEREAL MUSIC, WOMAN VOCALISES) The impact of the full moon is felt all along the coast. It makes fiddler crabs frisky. The power of female choice is such that the male's claw is the largest sexual adornment relative to body size of any animal in the world. A female sets out to select her mate. She's spoilt for choice. The males display in synchrony. (GENTLE MUSIC) (MUSIC CONTINUES) (MUSIC CONTINUES) (MUSIC CONTINUES) It may be that, like the fireflies, females have a preference for the male that displays first. The female picks her male and goes down a burrow to mate. (ETHEREAL MUSIC, WOMAN VOCALISES) The moon has a mysterious power. It rules the animals of the mangrove forests and the reefs. It stirs the oceans and creates plankton-laden currents. And for many creatures, it is the key that unlocks their sexual lives. While the moon is an enigmatic force, it is the mighty tropical sun that dictates the lives of the plants and animals of the greatest forests on Earth. - (HOOTS) - And that is where Islands In Time goes next. Captions by Julie Taylor. Captions were made with the support of NZ On Air. www.able.co.nz Copyright Able 2021