Poor Knights Islands- New Zealand’s Volcanic Ocean Sanctuary - FD Ocean

The Poor Knights Islands rise off the coast of New Zealand's Northland. Nearly 2,000 hectares of world-renowned marine wonderland and protected island sanctuaries, Aorangi to the south, Tawhitirahi to the north, and the many craggy pinnacles around them. Isolated. Protected. Forbidding. The Poor Knights Islands have no beaches. Or so it seems. There are beaches here. White, sandy, and entirely underwater. The Poor Knights Marine Reserve is one of the world's most pristine underwater environments. The towering architecture of its reefs provides habitats for light lovers, bottom dwellers, and everything in between. All the residents know their place. But order can break down in an instant. A devoted father can lose everything when hungry neighbors raid his nest of eggs. A female will change sex if she has to. Nothing is what it seems. It's dawn, and a sand dagger's wrasse wakes from his secret sleeping place. His bold colors identify him clearly as a male. But he began life as a she. Wrasses are a family of fish which are almost all born female, and most remain female all their lives. But each carries inside her the potential to become male. The boldly striped male can grow to around 45 centimeters, while the females, like this one with her juvenile, are smaller, in muted brown and white. The juveniles display a gold stripe and black tail dot for several months until they become adults. Together they form the male's harem, and their morning is spent foraging on the ocean floor. The sand daggers live on small, invertebrate animals found on the sandy seabed and among the algae growing on the reef. They suck food in and spit sand out. Fishing has been banned in the poor knight's marine reserve since the 1990s, and yet this female sand dagger's wrasse, with an injured mouth, may have survived being hooked by a poacher or attacked by a predator. Nearby, a stingray unwittingly provides cover for one of the poor knight's most cunning ambush hunters. The powerful kingfish attempts to hide beneath some of its unsuspecting neighbors as it stalks prey, waiting until the very last second to strike. The reef is full of camouflaged predators, each with one thing on their mind. It's summer here, and the population has swelled with exotic visitors which come here to breed and feed. The sea surrounding the poor knight's is a couple of degrees warmer than mainland waters. Here, warm waters from the East Auckland Current mix with colder southern seas, attracting a dazzling diversity of marine creatures, rarely found in one place. From cold water loving species like these blue moki, to the exotic, colorful subtropical visitors, and this New Zealand native, the blue maumau. They congregate in the poor knight's arches by the thousands, feeding on the abundant zooplankton. As father and mate, this male sand dagger's wrasse supervises his harem closely, even controlling the female's food intake so they don't get big enough to threaten his authority. His neighbor, the demoiselle, has an entirely different approach to family life. Less than half the size of the sand daggers, demoiselles range from almost black to pale blue, but almost always display their distinctive white dorsal dots, two on each side. Like the sand daggers, this male demoiselle has a family to protect, only they are not born yet. Clinging to this rock, invisible amongst the furry brown algae, are hundreds of demoiselle eggs. In just a week, they will hatch, but only if the male maintains his vigil. There are plenty of fish in this neighborhood who will happily help themselves to a meal of juicy, defenseless demoiselle eggs. Between the sand daggers and the demoiselles, there's an uneasy coexistence. In just a moment, these tolerant neighbors can turn on each other, and social order can break down entirely. As recently as 18,000 years ago, a mere blink in geological time, the Poor Knights Islands were part of the New Zealand mainland. Since the last ice age, the sea has risen 120 meters, and now the Poor Knights are isolated 22 kilometers off the coast. The islands are the disintegrating remains of a once huge volcano, asleep now for 10 million years. As it slept, the pounding seas did their work, eating away at the rock, until all that is left of the once mighty volcano are the inhospitable, craggy tours of Tawhitirahi, Aorangi. The island's interiors are thick with native forests. Deep below, another kind of forest thrives. Lush Lasonia kelp, sargassum, and sea lettuce are both food and shelter for many marine animals. For the black angelfish, it's also a garden. In his handsome all-black outfit, with white lips and single white ear dot, this fastidious vegetarian doesn't just guard his chosen food source, he cultivates it. This male nibbles just enough algae to feed himself, leaving a neatly groomed lawn ready for a female to lay her eggs on, if he's lucky enough to find a mate. While a black angelfish can grow to 28 centimeters, just a couple of rocks away, his neighbor is a quarter of his size. The crested blenny is a cleaner fish. It's a dangerous world out there when you're no bigger than a finger. So the blenny finds himself a cozy hold in a rock, and lets the world come to it. These demazels have come to the blenny with a problem. They have lice, and blennies eat lice. With their sharp little teeth and even sharper reflexes, the blennies pick parasites off larger fish. It's a win-win situation. If the demazels seem nervous, it's because the blenny occasionally takes a bite, or fish. Parasite-free for now, the demazels move on to a far greater challenge. The turning tide brings fresh plankton into their domain, but the demazels must make a perilous journey to the surface to get it. It's a high-risk venture for these little fish, so they travel in a convoy for safety, never straying far from the reef. Demazels' eyes are close to their mouths, which helps them see their food, as their flexible lips scoop zooplankton from the water. The rewards of their journey are great, but so are the risks. At the surface, they have to hold their own with far bigger fish. A large predatory kingfish slips in among the silvery snapper and little demazels. It's also here to feed, but not on plankton. Demazels are more to its taste, although even greater danger comes from above. These deadly hunters are gannets, or takapu. The serrated cliffs of the smaller Poor Knights Islands make perfect nesting colonies for over 4,000 gannets. With no rivers on the islands to wash silt into the sea, the gannets can easily spot their prey in the clear water. They tuck their wings in and hit the water at up to 145 kilometres an hour. Inflatable air sacs around their necks absorb the impact, then deflate once they surface, allowing them to swallow their prey. Not all demazels make the dangerous migration to the surface. Summer is breeding season, and many males already have eggs in their rock nests to defend. But this doesn't stop them enticing new females into their territory. When a female is ready to breed, her egg duct, called an ovipositor, extends beneath her body, ready to release her eggs. But she needs a little encouragement. The male demazel nuzzles the female's belly and rubs his body against hers to stimulate her to lay. As she flutters her body, she is depositing microscopic eggs amongst the algae on the rock, and he quivers as he inseminates the eggs. From this moment on, he is committed, not to her, but to the nest, until the eggs hatch in a week's time. He begins an exhausting vigil, seeing off any fish that come too close. The female, on the other hand, is free to head off to find another male. It's the summer of love at the Poor Knights, and everyone's pairing up. Few fish actually mate. Instead, they spawn. But many perform courtship rituals or show colourful displays. This male pigfish signals his amorous intentions with dashing white eyeliner and a flashy dorsal dot. They'll fade once he's completed spawning. The sand dagger's approach to breeding is less colourful. Spawned in open water, the eggs are left to take their chances as part of the plankton soup. And plankton is what everyone round here eats. What family he has, the sand dagger supervises very carefully. This female, in drab brown and white, is just one of many in his harem. And he's pretty tough on all of them. It's not just to keep them in line. It's to keep them female. All female sand daggers carry the potential to become male. But he doesn't want another male in his territory. His domineering behaviour keeps the females stressed. And stress stimulates estrogen, the hormone that keeps the females female. But there's one aspect of life in his little rocky kingdom that even he cannot control. Poised in the Pacific, like a tuatara ready to pounce, the island of Tawhitirahi is a theatre of war. A feud has been rumbling around the poor knights for millions of years. Two ancient natives. One predator, one prey. New Zealand's largest reptile, the tuatara. And the giant weta. The tuatara family has been around for 250 million years. Extinct on the mainland except in captivity, tuatara can only survive on predator-free island sanctuaries. They are the poor knight's top land predator. They hunt lizards, frogs, chicks, eggs and giant weta. A species that's only been around a mere 190 million years. Weighing up to 50 grams, weta are one of the heaviest insects in the world. Rats, cats and stoats are kept at bay by the poor knight's forbidding cliffs and spires. And those 22 kilometres of ocean. Keeping tuatara safe. But not their prey. A hundred metres below them, another ancient creature patrols. Stingrays have been around for over 140 million years. Before the dinosaurs died out. Famous for the poison in their barbed tails. They only use these weapons in self-defence. Rays have no bones. They're all muscle and cartilage. Just like their close relatives, sharks. But they're not great predators. They just eat shellfish on the ocean floor. This female short-tailed stingray is looking for food. Only she's never going to see it. Her eyes sit on top of her head to watch for potential predators above. So she finds her food using sensory organs called ampullae of Lorenzini. Located around her mouth. They detect electrical charges emanating from creatures in the sand. She vacuums up great mouthfuls of seabed. Grinding up the good stuff with her teeth. And blowing the rest out through her gills. Every summer, large numbers of rays migrate to the poor knights from the open ocean. And gather in its towering underwater arches to breed. Sometimes, they exhibit a behaviour rarely seen anywhere else in the world. Long-tailed and short-tailed stingrays hover between the arches. One stacked above another. Riding the current flowing through these narrow passes. This behaviour might be connected with mating. But for now, it's a mystery these animals are keeping undercover. A pink female pigfish checks out a tiny yellow clown tado. But possibly knows not to get too close. Like the stingrays, it too has a venomous secret weapon. It's a kind of pufferfish, which have a poisonous gland inside them. Few fish eat a clown tado and live to do it again. The poor knight's reef abounds in gorgeous urchins, anemones, sponges and corals. They may look like plants, but they're all animals. In that they eat and even have mouths. Although some of the prettiest may turn out to be an animal of a different sort. A scorpionfish can mimic a coral-encrusted rock in the blink of an eye. These nudibranchs are animals. These two are even mating. Nudibranchs are soft-bodied mollusks and are highly toxic. In the visual language of the sea, bright colours spell poison and warn other animals to stay away. In among the garden-like colonies of sponges and corals, the demoiselles lay their precious eggs. For the guarding male, keeping his embryonic young alive means keeping them fresh. Every few minutes he fans them with his pectoral fins, which re-oxygenates the water. The much larger black angelfish chooses a smooth vertical face for his nest. This one has found an excellent niche, but its secluded location is no deterrent to prying neighbours. His white ear dot signals his defensiveness. He turns it on when guarding, off when courting. In every direction, devoted fathers are trying to protect their young. The demoiselle and the black angelfish have this in common. If either male takes his eye off his young, even for a moment, hungry neighbours will mob the nest and a whole generation becomes lunch. The Poor Knight's Islands are forever changing. The forces of tide, wind and salt smash these cliffs relentlessly, sculpting them into dramatic arches and caves, and sending great slabs of rock plunging into the ocean. Here on the seafloor, each fallen boulder hosts a miniature ecosystem, home to colonies of algae, anemones and demoiselle eggs. The devoted demoiselle dads continue their demanding vigil. While unattached demoiselles are free to forage for food, the nest-bound fathers have to get by on whatever planktonic scraps float past. He must keep the nest site free of obstacles and never drop his guard. As egg predation is common, the more aggressively he defends his patch, the more likely his young will make it to hatching. But with so many hungry neighbours around, there's only so much one fish can do. It only takes a second as he chases off one intruder, for another to sneak in and sniff out his eggs. Then others get the same idea. A female sandagger's wrasse starts to eat his eggs. Then more of her harem join in. Within seconds there's a feeding frenzy, and most of the culprits are other demoiselles. A sandagger's male pushes in, and two usually vegetarian black angelfish are part of the carnivorous throng. Somewhere in there is the father of all the disappearing eggs, helplessly trying to repel the mob. It's an exercise in futility. After all that work, clearing the space, attracting a mate, guarding and aerating the eggs and going without food, there's nothing for it but to start all over again. As night falls over the poor knight's islands, the tuatara is in his element. Its eyes have cells adapted for day and night vision, making it an invincible night hunter. The giant weta heads for the trees. But tuatara can climb trees too. While the adults hunt, the juveniles shelter in burrows. By day they swap places. It's safer that way, as tuatara adults are known to cannibalise their young. This young tuatara is not long hatched from its egg. Its gender was determined by temperature before it hatched. Eggs kept warmer produce male offspring. Cooler temperatures produce females. So global warming threatens the tuatara's very existence. As the day draws to an end beneath the ocean's surface, the daytime species either hide or adopt camouflage colours for the night. The sandagger's wrasse seek refuge, while their neighbours, the goatfish, sweep the floor for a final meal. Their lurid pink will dwindle to mottled sandy tones. The marblefish hunkers down in a crevice. And the fluorescent pink maumau turns it down a little, turning blotchy to blend in with the reef. The blennies retreat into their holes. And the demoiselles snooze in a cave with a sleepy porai. The most secretive sleepers of all are the sandaggers. For a long time, their resting place was a great unknown. At night, sandaggers couldn't be found. Not in caves, under rocks, or in the kelp. They just seemed to vanish. Until night divers uncovered their secret. Supervised by the male, the females and juveniles bury themselves just under the sand. Finally, when all his harem are hidden, the male burrows in too. Hidden, but still vulnerable. Now the night predators come out to hunt. The fierce but paper-thin John Dory flashes its evil eye to make predators think they're seeing the face of a huge creature. Several species of moray eel are also night hunters in the poor night's neighborhood. Small filaments in their nostrils detect the vibrations of approaching dinner. The largest is the speckled moray, which can live for up to 30 years. It takes little note of this scorpionfish as it heads out in search of more bite-sized prey. The mosaic moray has sharp fangs, even in the roof of its mouth, so it can't entirely close its jaws. The mosaic pattern on its skin continues inside its mouth to confuse prey. They can't tell if it's open or closed. The gray moray lies in wait like the others, but also ventures out to hunt. It can detect food buried in the sand. In their hiding place, the sand daggers sleep on, somehow keeping enough water flowing over their gills so they can breathe. Just above them on the reef wall, the reclusive scorpionfish bides its time. This master of disguise positions itself and waits for unsuspecting prey to swim by. But not all the creatures of the night are out to kill. Like most of the poor knights, stingrays mate in summer too. A female is easy to identify by her flat, fanned tail fins, whereas a male has modified fins called claspers, which serve as sexual organs. Stingray courtship is a risky business for the male. If the female is not interested, she may use that venomous tail barb to get her point across. If he does find a willing female, he sinks his teeth into her and hangs on tight. She may conceive straight away, but female rays are also known to sperm bank, holding the sperm in their bodies for months until they decide the time is right to conceive. Far below the rays, the sand daggers are buried and safe, so long as no predator discovers their hiding place. But a thin layer of sand offers only so much protection. First light pierces the clear waters around the poor knight's islands. In the dark, below the overhanging reef, the sand daggers are still asleep under the sand. Nothing stirs, but a grey moray eel. They have been known to kill and eat sand daggers. The creatures of the night now seek the darkness of the caves, and the daylight species stir. Pink Mau Mau take things pretty slowly, never burning up much energy, whereas from first light, the black angelfish seems to be in a state of constant agitation. He's got one priority, keeping his eggs safe until they hatch. The morning sun starts to hit the seafloor, but many corners of the reef remain in shadow. The stingrays slip into the sandy seabed to rest, just as the sand daggers are rising for the day. After a night breathing beneath the sand, the sand daggers are hungry and need to feed. But something is wrong. One of the females has been bitten right through her body. It's impossible to know what did this. Perhaps it was the grey moray eel. But the sand dagger's females have a far bigger problem. The male has disappeared. Whatever has happened to him, his harem is left without a leader. For most of the demazels, today is just another day. Undeterred by the destruction of their neighbor's nest, they continue to court, breed, and guard their eggs. By luck and good management, some have brought their brood to hatching. These minute demazels are three weeks old and already feeding in open water, where there's plankton small enough for their tiny mouths. Those which survive to breeding age will be guarding their own nests by the time they're four or five years old, and pestering their neighbors, the little blennies, to attend to those itchy parasites. The harem of female sand dagger's wrasse get on with their day without their leader. But one of the females is already taking over his role in an extraordinary way. The minute there's no male, the females have no stress. Without stress-promoting estrogen, the hormone which keeps them female, they start to become male. They grow bigger very quickly. And although a few females might begin the process, the biggest female has a head start. She immediately starts to behave like a dominant male, putting the other females under stress again, which increases their estrogen and stops them from going any further towards becoming male. But this biggest female doesn't just behave like a male, she becomes one. A radical physical transformation begins. Her ovaries will turn into testes. She will grow 10 centimeters longer, and her muted colors will morph into the bold and brassy uniform of a male. In only two weeks, the transformation will be complete. And she, now he, will be ready to father a new generation of sand dagger's wrasse, which will grow, breed, and establish their own little kingdoms in this beautiful corner of our big blue backyard.