Living World Archives | New Zealand Geographic

Baby boxers

The mantis shrimp subdues its prey by punching it with a blow that’s strong enough to crack a glass aquarium and generates enough heat to boil water. So when do baby mantis shrimp develop this super-smash prowess? To find out, Duke University researcher Jacob Harrison headed to Hawai‘i with a high-speed camera in search of Gonodactylaceus falcatus larvae—one of the world’s 450 species of mantis shrimp. First, he had to catch a four-millimetre-long larva. “It can be incredibly challenging to sift through a bucket teeming with larval crabs, shrimp, fish and worms to find the mantis shrimp,” says Harrison. Then he had to position the larva in front of his high-speed camera—a task that ended up taking a year to perfect (and involved supergluing the larva to a toothpick). But the effort was worth it. The high-speed footage revealed the mantis-shrimp punch in action: the limb bending back like a spring, before a tiny latch is released that flings the appendage forward with impressive acceleration and speed—around 38 centimetres per second. While the larva was slower than full-grown adults, the jabs were still five to ten times faster than the swimming speed of similar-sized organisms, and 150 times speedier than their prey. After raising some larvae from eggs, Harrison observed that they first began to hunt with their forelimbs between the ages of 9 and 15 days. Although young mantis shrimp go through six to seven transformations from hatching to fully grown, Harrison’s footage showed that the spring-and-latch mechanism is the same in young and old. And while the larva’s punch may be scaled down, the transparent exoskeleton of larvae revealed remarkable detail previously unseen: the tiny muscles contracting as the mantis shrimp wound up for another devastating blow.

Geo News

Not an alpine parrot after all

Kea are the mischief-makers of the mountains, but a genome study shows they are not tied to alpine areas. As rising temperatures shrink their habitat, they could return to lowlands—if they can find suitable places to live. Fossils suggest that kea once occupied low-lying areas throughout the South Island and even in the North Island. In fact, there’s nothing “to stop kea from living at lower altitudes”, says University of Otago evolutionary geneticist Michael Knapp. The research scoured the genomes of kea and its sister species kākā, which is adapted to life in the forest, for any genes known to be involved in adaptation to life in the mountains. The commonly held theory was that kea and kākā went their separate ways about two or three million years ago, when the Southern Alps were still rising and opening up new alpine habitats. But Knapp says an ice age was redrawing the landscape at the same time, reducing forests in its wake. “For the ancestors of kea and kākā, their forest habitat shrank, and that made it more likely that some populations ventured into new habitats. That’s what distinguishes them—the kea is the species that went into the open.” The kea’s later retreat to alpine altitudes may have had more to do with avoiding people—including a bounty-hunting scheme that lasted more than a century, from 1867 to 1970, and killed some 150,000 birds. Thankfully, the genome doesn’t show a genetic bottleneck, which suggests the bounty-hunting period was short enough to avoid denting the birds’ genetic diversity, says Knapp. But the study has found a significant difference between the two parrot species. Kākā respond quickly to improved living conditions. When forest cover expanded in the past, so did kākā populations. In contrast, the kea population remained relatively constant, regardless of habitat changes. “Is the kea better at buffering bad habitats, or not so good at responding to good conditions?” asks Knapp. Both species may struggle to adapt to a warming world, says University of Otago PhD candidate Denise Martini. “If native forests begin to suffer from warmer conditions, it is very likely that kākā will suffer, too. Kea might be able to adapt to new conditions, but that depends on whether new conditions are available in the first place. My recommendation for conservation programmes would be to focus on restoring and preserving as much of the existing habitat of both species as possible.”

Short - Better Ancestors

The call of the kōkako

Parininihi consists of 2,000 hectares of coastal and inland forest in Taranaki and Conrad O’Carroll has committed his life’s work to caring for it and its resident kōkako population by managing introduced predators and teaching the next generation of kaitiaki / guardians. Ngāti Tama are tangata whenua and kaitiaki of Parininihi and these lands hold great cultural, historic and spiritual significance to Ngāti Tama, who strive to maintain the health of Parininihi. Kōkako (Callaeas wilsoni) are of the genus Callaeidae, Wattle Birds, and very distant relatives of the crow. They were previously widespread in Aotearoa. However, populations have been decimated by the predations of mammals such as possums, stoats, cats and rats, and their range has contracted significantly. With their extraordinary haunting song, and obscure evolutionary relationships to other birds, they evoke the forests of ancient Aotearoa. And Conrad - and people like him - are trying to rescue taonga species, including kōkako, from the precipice of extinction. @betterancestorsnz

Short - Better Ancestors

Teaching green

Tania de Basin's mission to show primary students the link between responsibility and sustainability.

Short - Better Ancestors

The community saying no to waste

Inside Xtreme Zero Waste's collaborative success in Raglan.

Books

Life lessons from the animal penis

The penis of the leopard slug, Limax maximus, is translucent blue, frilly, and as long as its entire body—and it just gets weirder from there.

Geo News

Glow-in-the-dark sharks

In January 2020, Jérôme Mallefet went looking for glowing sharks on the Chatham Rise, off the east coast of the South Island. As researchers on the NIWA ship Tangaroa hauled up trawl nets full of hoki for their annual fisheries survey, Mallefet kept his eyes peeled for bycatch. He and colleagues collected more than 600 deep-sea sharks, representing three species, and transferred 24 into tanks in the wet lab. As the ship pitched and rolled, they photographed the sharks in the dark. They discovered that all three shark species had the ability to glow: two small lanternsharks, and the kitefin shark, Dalatias licha, which reaches up to 1.8 metres in length. That makes the kitefin shark the largest light-producing creature—with a spine—that has ever been found. Mallefet, an expert in bioluminescence from the Catholic University of Louvain in Belgium, says other studies suggest that around ten per cent of the Earth’s approximately 540 shark species can glow. So why do they do it? Partly to recognise each other in their deepwater home, as each species lights up in a particular way. It may help males and females align for reproduction. And glowing can also make the sharks invisible. “These guys are living in the twilight zone, where there is a bluish faint light coming from the surface,” says Mallefet. Seen from beneath, the animals’ bodies appear as silhouettes against the light. But when the kitefin shark illuminates its entire belly with a blue glow, it blends into the light from above. “Suddenly you disappear—that’s how counter-illumination works.” Their dorsal fin also glows—but why remains a mystery. Other recent studies have shown that as many as three-quarters of marine animals in the water column have the ability to make their own light. “Bioluminescence is so widespread, it must have a really critical role for the survival of these organisms down there,” says Mallefet. “The way they communicate, the way they reproduce—bioluminescence plays a role in it, and we are only just discovering that now. “It must be glowing Christmas trees everywhere down there, that’s for sure.”

Geo News

Fish dine by moonlight

The phases of the moon affect how fast baby fish grow, a new study has found. Ecologist Jeffrey Shima from Victoria University of Wellington and colleagues found sixbar wrasse larvae grew fastest during the last quarter of the moon—when the first half of the night is dark, and the second part is bright. That’s because when reef fish release their larvae, these float out into the open ocean to feed. There, they meet the mass migration that takes place every night as millions of fish and plankton rise from the deep to feed, then sink before dawn to hide in the dark. Baby sixbar wrasse feed on plankton, which rise more quickly than their predators. But when predators such as lanternfish arrive at the surface, they use their bioluminescent tummies to camouflage themselves against the moon’s light and sneak up on the wrasse. Shima’s hypothesis is that when the moon is full, it’s too bright for plankton to feel safe and for predators to properly conceal themselves, so neither rise all the way to the surface. That leaves the wrasse hungry, but safe. On dark nights, there’s plenty of food—and plenty of lanternfish. But during the last quarter, when the moon rises at midnight, the plankton have already reached the surface, and by the time the predators join them, it’s too bright for them to hunt successfully. The wrasse larvae feed freely and grow more quickly. “This has really big implications for explaining why we see a lot of variation in the survival rates of baby fishes,” says Shima. “If you have months that are more cloudy than average, that might have serious consequences.” Artificial lights from cities may also disrupt these natural cycles.

Geo News

Ears on the ocean

The ocean is awash with noise. The clicking of shrimp snapping their claws, the crunching of reef fish grazing, the rumble of a vessel passing overhead—sound travels fast underwater, and in all directions. For animals that rely on sound for communication, such as whales, a cluttered soundscape can be stressful, causing them to change their behaviour. To hear what whales hear—and map where they go—researchers deployed four acoustic recorders in the waters around central New Zealand, collecting soundwaves at various frequencies. The recorders detected the ethereal calls of four whale species: pygmy blue, Antarctic blue, humpback and Antarctic minke whales. Pygmy blue whales were abundant in the South Taranaki Bight, with some visiting Kaikōura in autumn. The other species passed by New Zealand on their annual migration between the tropics and Antarctica. The sound recorders also captured the whooshing ambient background of rain, tides, waves and wind, even earthquakes. Human-generated noises from seismic surveying and ships were also common, and at times overlapped with the whales’ calls. The researchers say this audio information helps identify places in the ocean where human noise might be limited for the whales’ benefit. Whales aren’t the only animals facing hearing problems. Growing up in acidic waters can cause hearing damage in snapper, according to a different study by New Zealand and Australian researchers. Young snapper raised in conditions with elevated carbon dioxide levels were significantly less sensitive to low-frequency sounds. This diminished ability was attributed to changes in the structure of their ear bones and brain chemistry resulting from increased acidity. Hearing is critical for many fish species, playing an important role across their lives: from larval fish deciding where to settle, to individuals synchronising for spawning, to making contact with others.

Geo News

Tracks of the tohorā

In issue #166, New Zealand Geographic covered a research project to track tohorā/southern right whales and learn where they swim over the summer. The results are in. As this issue went to print, only one whale’s transmitter was still functioning, that of Wiremu, the whale named after New Zealand Geographic journalist Bill Morris. Wiremu/Bill is the light blue line travelling along the coast of Antarctica.

Features

The occupation

Wallabies may have evolved in Australia, but they’re so well suited to life in New Zealand that they have reached plague numbers for the second time in a century, eating their way through the landscapes of Canterbury and the Bay of Plenty and escaping from the containment zones created to hold them back.

Short - Songs of the Sea

A song for the hāpuku

Pioneer diver and lifelong environmentalist Wade Doak laments the loss of the hāpuku, our behemoth groper that was once common even in shallow water in the Hauraki Gulf.

Short - Songs of the Sea

A song for the Noises

Sue Neureuter grew up visiting the Noises Islands which have been in her family since the 1930s. Having witnessed the decline in marine life and seabirds in the Hauraki Gulf first-hand she recalls her parents' stories. “When Mum first got to the Noises which was the late fifties, Dad used to make her row out and he’d put his rugby jersey on and plop over the side and pick crayfish up and dump them around her feet.” This personal account is the first of a New Zealand Geographic-produced web-series—made in association with Live Ocean and Pew Charitable Trusts—that examines the former abundance of the Hauraki Gulf through the memories of those who can still remember these Songs of the Sea.

Geo News

The kiwi’s sixth sense

When a kiwi probes soil with its long beak, it’s not only scenting for prey, it’s using an extra sense to detect the wriggling vibrations of a grub. Known as “remote touch”, this ability is due to a special organ on the tip of its bill. Some shorebirds, such as the royal spoonbill, also have these beak mechanoreceptors to help them locate their prey in mud. Emu and ostriches have similar remote-touch organs in their bills, although they don’t forage by probing, or have any other habits that rely on this sixth sense. These birds are part of the palaeognath family, which includes moa. Could their remote-touch sense be a remnant from a distant ancestor of both moa and kiwi? Scientists from South Africa traced the palaeognath family tree back to the extinct lithornithids—long-legged, beak-probing birds that evolved during the Cretaceous period, more than 66 million years ago. To figure out if these avian ancestors had the remote-touch sense, the researchers compared the skeletal structures of 353 living birds with and without bill-tip organs, looking for patterns that would allow them to decide whether a fossil had the organ. Remote-touch organs are embedded in bony pits in the beak, and analysis of fossil bones suggested that the ancient birds did have bony pits and the extra sense of wiggle detection. Moreover, the fossils had been found by lakebeds, suggesting the lithornithids had foraged in mud, too. The researchers speculate that the remote-touch sense may have evolved even earlier: in the sensitive snouts of dinosaurs.

Geo News

Newest family member

Emerald green with a distinctive yellow smile: meet Naultinus flavirictus, the newest addition to New Zealand’s treasure trove of more than 100 endemic lizard species. Found in the Far North, this gecko has been recognised as a distinct species since at least the late 1990s. It was finally described and named in a January 2021 paper published in Zootaxa, based on three specimens held at Te Papa Tongarewa. Its name refers to the yellow markings at the corner of its mouth. With its small home range and the ever-present threat of invasive mammals, the newly minted N. flavirictus is classified as “at risk” of extinction. The study’s authors speculate that these geckos once occupied tall, subtropical rainforest—which has dwindled to 3.2 per cent of its former extent since human arrival. The Te Paki area of Northland is a biodiversity hotspot, home to an array of unique and rare species, including 17 plants, 30 land snails, several stick insects and one skink found nowhere else. N. flavirictus is the ninth gecko in the Naultinus genus to be formally described. Its other eight family members are scattered around the country.

Geo News

Octopuses beat up fish

Scientists have filmed multiple instances of octopuses punching fish in the Red Sea during so-called collaborative hunting expeditions. An octopus may join forces with several species of fish to increase its chances of nabbing a meal. Groupers patrol the water column, using gestures to signal where prey is hiding. Octopuses can reach into tight cracks with their tentacles. Other species, like goatfishes, may scour the seafloor and join in a pursuit. To untangle the dynamics of these complex inter-species interactions, researchers filmed several cooperative hunting bouts using underwater cameras. They filmed eight instances of octopus-on-fish violence, finding a number of possible reasons for the octopus picking a fight. For example, if a fish partner failed to pull its weight or took more than its fair share, they might receive a jab. A sneaky parasitic fish might be shooed away with a tentacle. Sometimes, the octopus punched fish out of the way in order to take the prey for itself. Collaborative hunting also occurs between reef fish and moray eels—but, eels don’t have arms.

Geo News

Catchy songs

How do you trace the travels of a humpback whale? You listen to its song. Whales learn songs from each other, so their vocal patterns are clues to who they’ve been hanging out with—and where. Every winter, humpback whales leave their Antarctic feeding grounds and swim 5000 kilometres north to the tropics to breed. Some swim up the east coast of Australia, while others pass through New Zealand waters. Rochelle Constantine and Victoria Warren from the University of Auckland analysed acoustic recordings of humpback whale song to figure out the likely destination of individuals passing by New Zealand. They compared local whale recordings—captured off Kaikōura, the Wairarapa, in Taranaki Bight and Cook Strait—to audio samples from both eastern Australia and New Caledonia. The New Zealand songs shared more similarities with recordings from New Caledonia than from Australia, suggesting a stronger connection with the breeding grounds around the French archipelago. Eavesdropping on the whales also taught researchers about their preferred migratory routes. On their way north, most whales followed the east coast of the South Island, hung a left through Cook Strait, then powered north.

Geo News

Following petrels back home

Ornithologist Colin Miskelly was up before dawn, his face lit by the reflected glow of his laptop, entering data into a spreadsheet while his expedition boat lay at anchor in Doubtful Sound. At 5.35am, something soft—“like a feathered butterfly”—hit him in the chest. Miskelly grabbed it—and there, its heart beating against his hand, was a grey-backed storm petrel. You may not have heard of this New Zealand bird, and you probably haven’t seen one, either. That’s because they spend most of their lives at sea, and were thought to breed only in the country’s farthest outposts: the subantarctic and Chatham islands. None of New Zealand’s early naturalists recorded grey-backed storm petrels anywhere on the mainland. But one was collected in Preservation Inlet in 1889, and there have been occasional sightings in Fiordland over the past 50 years. Seabirds only really hang out near land when they’re breeding, says Miskelly, “because no bird has ever figured out how to incubate a floating egg”. So are they a mainland bird after all? Hoping to solve this mystery, Miskelly’s team had spent much of the November 2020 research trip looking for grey-backed storm petrels, shining the ship’s spotlight into the sky on dark nights to attract them onto the deck. They had caught five birds, and seen them at six different sites along a 120-kilometre stretch of Fiordland’s northern coastline—but this one had landed in Miskelly’s lap. And it had a bare brood patch. “That pretty much says this bird is caring for an egg or very young chick at this moment and therefore should be within a day or two’s flight of its nest or possibly even closer,” he says. In 2017, Miskelly—who is Te Papa’s vertebrates curator—had caught another storm petrel with a brood patch at Chalky Inlet at the far southern end of the fiords. Together, the signs point to the species “breeding throughout the length and breadth of Fiordland”, probably on steep cliffs that are inaccessible to rats and stoats (and researchers). To prove this, Miskelly would need to GPS-track the birds, but this would require tracking devices that are lighter and more powerful than existing ones. Or a storm-petrel feather could turn up in the nest lining of one of Fiordland’s alpine rock wrens—a method previously used to indicate the presence of kākāpō.

Features

The birds and the bees

Plant sex is the ultimate form of a long-distance relationship, with animals co-opted into carrying out the act. The result: much of life on Earth depends on the habits of hungry insects, bats, reptiles and birds. But we don’t know exactly who’s doing what to whom, and when—and what might happen if they disappear.

Geo News

Deep-sea sperm bank

Some female sharks and rays living in the deep ocean can store sperm inside their bodies for years at a time, until the moment is just right for conception. Adèle Dutilloy from the National Institute of Water and Atmospheric Research (NIWA) examined the reproductive organs of 147 female sharks and rays from nine species. Inside three of those species—the longnose velvet dogfish, the leafscale gulper shark, and the smooth deep-sea skate—were microscopic tubes of sperm, hidden in a tiny gland that produces the egg case. Dutilloy suspects most deep-sea sharks and rays have this feature, but the tubes are tricky to find. But why hoard sperm? It’s possible that in the dark, lonely depths of the sea, males and females don’t run into each other very often, so keeping some sperm for later allows females to reproduce more regularly. The second hypothesis is more disturbing. “Basically, there are gangs of male sharks, and when they encounter a solitary female, it’s all quite aggressive,” says Dutilloy. “When you see a female that’s been recently mated, she’ll have bite marks on the top of her back or on her fins. Females actually have more flesh on their backs than males do, to help account for that.” Dutilloy and study co-author Matt Dunn think that long-term sperm storage means female sharks don’t mate as often, and suffer less physical injury. Understanding the sex lives of these creatures gives scientists more insight into their life cycles—which in turn may shed light on whether they’re under threat from New Zealand’s trawl fisheries. “We know very little about them,” says Dutilloy.

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