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    Dazzling underwater photos capture new views and scientific detail of fish larvae

    The open ocean is a veritable soup of tiny critters, including newborn fishes. It’s hard to learn about them, though, because they are mere millimeters long and semitransparent. When netted from research vessels, their delicate body parts may get mashed or removed. Now, a partnership between scientists and scuba divers is giving researchers fresh perspectives on the secrets of larval fishes.

    Underwater photos taken at night — when larval fishes migrate to within 200 meters of the ocean surface — reveal colors, body structures and behaviors that could never be seen in preserved specimens. Examining those same fishes back in the lab lets ichthyologists match the photographed larval fishes to known species, researchers report March 30 in Ichthyology & Herpetology.

    Scientists at the Smithsonian Institution and the National Oceanic and Atmospheric Administration hatched a collaboration in 2016 with blackwater divers — who enter the ocean in the dark of night — to photograph larval fishes and collect them as specimens. With lights in hand, divers Jeff Milisen and Sarah Mayte snapped up-close photos of nearly 80 larval fishes, then gingerly captured and shipped them to scientists to be studied alongside their mugshots.

    “Fish larvae that looked utterly drab as specimens have turned out to have brilliantly colored markings and fantastic structures,” says Ai Nonaka, a larval fish expert at the Smithsonian’s National Museum of Natural History in Washington, D.C.

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    Fragile appendages

    Specialists like Nonaka sort out larval fish identities by looking at body shapes and minuscule features through microscopes and by analyzing DNA of larval tissue. Unlike their swimming parents, fish larvae drift on currents, and their strange body parts — adaptations for a drifting lifestyle — make larvae look nothing like adults. 

    “Larval fishes are extremely difficult to identify,” says Dave Johnson, an ichthyologist also at the Smithsonian. Scientists have mistakenly given larval fishes new scientific names, not recognizing them as early life stages of known species.

    Because larval fishes are soft and fragile, they don’t travel well. Larvae lose fins and other delicate structures that evoke their behavior. The scalloped ribbonfish (Zu cristatus) larva, for example, has spaghetti-like ornamental fins sprinkled with white spots that get broken off on specimens. The way these ornamental structures appear to flow out like tentacles in the images of wild larvae suggests the larvae could be jellyfish mimics, say the study authors.

    Scalloped ribbonfish (Zu cristatus) larva in the oceanJ. Milisen

    Scalloped ribbonfish (Z. cristatus) larva specimenA. Nonaka/Smithsonian NMNH

    The trailing guts of a barbeled dragonfish (Aristostomias sp.) larva get mashed or broken off altogether, but the undersea photo reveals it coiled up into a tight corkscrew. Nonaka and Johnson confess that scientists don’t yet understand the function of the trailing guts seen in some larval fishes. One theory is that exposed innards might somehow increase digestion efficiency, while another suggests they could confuse predators.

    Barbeled dragonfish (Aristostomias sp.) larva in the oceanJ. Milisen

    Barbeled dragonfish (Aristostomias sp.) larva specimenA. Nonaka/Smithsonian NMNH

    Hidden colors

    Ethanol preservation of specimens repels bacteria and fungi, but leaches out colors. The three-spot righteye flounder (Samariscus triocellatus) larva, bone white as a specimen, is bright blue. Its dorsal and anal fins are fringed with white, and rows of yellow spots dot the base of the fin rays. While their function has yet to be studied, it’s possible that these borders create a flickering visual effect to help the fish escape from predators, suggests Geoff Moser, a retired NOAA fisheries biologist not involved with the study. Called “flicker fusion,” it’s been examined in other animals such as striped snakes as a form of camouflage on the go.

    Three-spot righteye flounder (Samariscus triocellatus) larva in the oceanJ. Milisen

    Three-spot righteye flounder (S. triocellatus) larva specimenA. Nonaka/Smithsonian NMNH

    The deep-sea tripodfish (Bathymicrops sp.) is plain and pale when prepared as a specimen and uniform brown as an adult fish — not exactly a looker. But the larva appears to have donned a clown costume with large white and orange polka dots flecked on its otherwise blue-hued body. In an ethanol specimen, its pectoral fins look soft and ghostly, whereas the living larva sports flamboyant, spiky and spotted fins. The function of the coloration is unknown. says Nonaka, but it could also be a flicker fusion trick.

    Deep-sea tripodfish (Bathymicrops sp.) larva in the oceanJ. Milisen

    Deep-sea tripodfish (Bathymicrops sp.) larva specimenA. Nonaka/Smithsonian NMNH

    Fishy behavior

    In larval specimens, scientists can observe some structures as evidence of behaviors. But undersea observations of wild larval fishes can show what they’re really up to when they are alive. The larva of the barred conger (Ariosoma fasciatum) is super flat, quite unlike the cylindrical adult. Yet a photo shows that it swims like an adult barred conger, by undulating its long body laterally. So, while it’s more svelte as a larva, it’s got some of the adult movements down.

    Barred conger (Ariosoma fasciatum) larva in the oceanJ. Milisen

    Barred conger (A. fasciatum) larva specimenA. Nonaka/Smithsonian NMNH

    Undersea observations can also reveal associations larvae have with other marine animals, including other tiny critters that also ride the currents. For example, a petite Pacific pomfret (Brama japonica) larva was caught on camera riding on a jellyfish. That’s a discovery that the study authors were unwilling to even speculate about. Although larval fishes have been seen taking shelter in the tentacles of jellies, hitching a ride on top of a jellyfish seems like an odd twist on that behavior.

    A pacific pomfret (Brama japonica) larva (pictured from three angles) in the ocean, riding a jellyfishJ. Milisen (photos); E. Otwell/Science News (collage)

    Pacific pomfret (Brama japonica) larva specimenA. Nonaka/Smithsonian NMNH

    Each larval fish that gets identified by scientists sets the stage for conservation. By knowing where larval fishes of particular species live, researchers can better advise on how to manage the ocean ecosystems the fishes depend on for survival.

    Conservation planning also requires knowledge of behavior (SN: 12/30/10). So photographing larval fishes and making their specimens available for identification means researchers get a handle on fishes’ behavioral adaptations for survival in the wild.

    “I’ve been working with fish larvae for over 40 years,” says Moser. “The chance to see these larvae in their environment was a wonderful advance in our scientific endeavors.” More

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    A year after Australia’s wildfires, extinction threatens hundreds of species

    When Isabel Hyman heads out in coming weeks to the wilds of northern New South Wales, she’s worried about what she won’t find. Fifteen years ago, the malacologist — or mollusk scientist — with the Australian Museum made an incredible discovery among the limestone outcrops there: a tiny, 3-millimeter-long snail, with a ribbed, dark golden-brown shell, that was new to science.
    Subsequently named after her husband, Hugh Palethorpe, Palethorpe’s pinwheel snail (Rophodon palethorpei) “is only known from a single location, at the Kunderang Brook limestone outcrops in Werrikimbe National Park,” she says. Now it may become known for a different, more devastating distinction: It is one of hundreds of species that experts fear have been pushed close to, or right over, the precipice of extinction by the wildfires that blazed across more than 10 million hectares of southeastern Australia in the summer of 2019–2020.
    “This location was completely burnt,” says Hyman, who is based in Sydney. “We expect the mortality at this site could be very high and … there is a possibility this species is extinct.”
    A year after the last of the fires were doused, their toll on species is becoming increasingly clear.  Flames devoured more than 20 percent of Australia’s entire forest cover, according to a February 2020 analysis in Nature Climate Change. Even if plants and animals survived the flames, their habitats may have been so changed that their survival is at risk (SN: 2/11/20). As a result of the scale of the disaster, experts say that more than 500 species of plants and animals may now be endangered — or even completely gone. 
    A wallaby licks its burnt paws after escaping a bushfire near Nana Glen in New South Wales on November 12, 2019.Wolter Peeters/The Sydney Morning Herald via Getty Image
    Australia’s iconic koala became the poster child of the crisis as images of rescuers carrying these singed marsupials out of the flames went global: As many as 60,000 of the nation’s estimated population of 330,000 koalas perished in the fires, ecologists concluded in December in a report for World Wildlife Fund Australia. While there’s no doubt that such charismatic megafauna suffered enormously, the greatest toll is likely to have been in other groups of species, such as invertebrates and plants, which often escape the public’s attention.
    As Kingsley Dixon, an ecologist at Curtin University in Perth told the Associated Press last year: “I don’t think we’ve seen a single event in Australia that has destroyed so much habitat and pushed so many creatures to the very brink of extinction.”

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    Koala charisma
    Even before the fires, many vertebrate species were already on downward trends, says John Woinarski, an ecologist at Charles Darwin University in Darwin. The blazes have “exacerbated the threats that were driving the declines,” he says.
    For example, fluffy arboreal marsupials called greater gliders (Petauroides volans) had already experienced a 50 percent population decline in recent decades. The fires then burned a third of their remaining habitat along Australia’s eastern coastline. An ongoing assessment may lead to the gliders being recategorized from vulnerable to endangered.
    Overall, 49 vertebrates that previously were not endangered now qualify for being listed as threatened under Australia’s guidelines for that designation, researchers reported in July in Nature Ecology and Evolution. That shift alone would increase the tally of nationally protected nonmarine vertebrate species by about 15 percent, from 324 to 373.
    Another 21 already threatened vertebrates had more than 30 percent of their ranges burned, and some may now qualify for being reassessed to higher categories of threat, the authors found. One species that may need to be recategorized is the koala (Phascolarctos cinereas), with some state’s populations that were hardest hit under consideration to be upgraded from vulnerable to endangered. 
    A koala named Paul recovers from his burns at an ICU in November 2019 after being rescued by volunteers following weeks of bushfires across New South Wales and Queensland.Edwards/Getty Image
    Besides the impact on koalas, the WWF Australia report suggests that as many as 3 billion individual mammals, birds, reptiles and frogs died or were displaced during the crisis. Though those figures are astounding, the impacts on lesser-studied groups such as invertebrates and plants may have been even greater.
    “Many of those have much smaller ranges [than vertebrates], which means they are going to be even more impacted when a big fire goes through,” says James Watson, a conservation scientist at the University of Queensland in Brisbane and an author of the Nature Ecology and Evolution paper on vertebrates. “I am willing to bet that there’s many species … that may disappear forever.”
    Invertebrate impact
    In February, more than 100 biologists convened the first of several online workshops to assess whether 234 Australian invertebrates now need to be added to the International Union for the Conservation of Nature’s Red List — a global who’s who of threatened species. 
    Snails, similar to many invertebrates, are particularly susceptible to wildfires, as they are unable to outrun flames and can’t survive intense heat, Hyman notes. Many also have small ranges that were completely incinerated, leaving no survivors that can recolonize the burned area.
    “A snail can’t do much to escape,” she says. “You could expect more than 90 percent mortality in a high-intensity bushfire.” In October, Hyman’s team published one of the first papers quantifying the impacts on invertebrates in New South Wales in the Technical Reports of the Australian Museum Online.
    The Palethorpe’s pinwheel snail (Rophodon palethorpei) has not yet turned up in searches following the wildfires, but other snail species did survive.Vince Railton, Queensland Museum
    Their surveys showed that 29 species in the state — including dung beetles, freshwater crayfish, flies, snails and spiders — had their entire ranges burned. Another 46 species had at least half their known habitat within the fire zones. These 75 species were among the 234 under consideration for adding to the IUCN Red List during the biologists’ first online workshop.
    “We’ve gathered together 230-odd species that are believed to now be of concern. These include a range of different taxa from land snails to millipedes to arachnids to insects, and this 230 is growing rapidly,” says Jess Marsh, an arachnologist at Charles Darwin University who was one of the conveners of the workshop. “I expect it will massively increase.”
    Some of the spiders she studies were the first to be added to that list. She’s already spent several months on South Australia’s Kangaroo Island hunting without luck for the Kangaroo Island assassin spider (Zephyrarchaea austini). Dependent on leaf litter suspended in the understory, and restricted to just a few locations that were razed in early 2020, she suspects that the species may be extinct.
    Spiders on Kangaroo Island such as this assassin spider (Zephyrarchaea austini) may now be extinct after most of their habitat was razed in early 2020.M.G. Rix and M.S. Harvey/ZooKeys 2012
    “There’s no understory vegetation left, let alone any leaf litter suspended in it, so that species is really hanging in the balance,” says Marsh.
    Generally, the species being considered for recognition as endangered had more than 50 percent of their ranges burned, lived in flammable parts of the habitat and have little ability to disperse to other areas. More than 150 of the 234 species being urgently assessed had their entire range burned. And it’s not just the flames themselves that are problematic; so is the reshaped environment following fires. Millipedes, for example, are very vulnerable not only to fire but also to drying out in the reduced shade and shelter of the post-fire environment.
    “A lot of invertebrates are very susceptible to desiccation, and need cover and humidity to survive a hot summer, which are obviously lacking following the fire,” Marsh says. “Taking into account all of the threats … we could be looking at significant numbers going extinct.”
    Rooted in place
    Lost vegetation hasn’t just put animals in danger. Many plants themselves may also be at risk, though experts have yet to compile an official list.
    Rachael Gallagher, a plant ecologist at Macquarie University in Sydney, has been prioritizing endemic plant species — those found nowhere else on Earth — that are in most urgent need of conservation for the Australian government. Perhaps surprisingly, she’s particularly worried about some trees that actually depend on fire to survive. Eucalypts known as alpine ash (Eucalyptus delegatensis) and mountain ash (E. regnans), for instance, are typically killed by fire and then regenerate from surviving seeds in the aftermath. Australia has many trees that must complete their entire life cycle from germination through to reproductively mature adult before the next major bushfire passes through (SN: 2/11/20). For some species, this may take 15 to 20 years.
    Some trees in Australia, such as this mountain ash (Eucalyptus regnans), depend on fire for their lifecycle, but recent wildfires may have been too much too soon.station96/iStock/Getty Images Plus
    The problem now is that climate change has increased the frequency of fires to the degree that many of these plants are unable to reach adulthood and set seed before the next fire passes through, meaning they may be lost from these ecosystems (SN: 3/4/20).
    The fires burned 25–100 percent of the ranges of 257 species of plants for which “the historical intervals between fire events across their range are likely to be too short to allow them to effectively regenerate,” Gallagher says. These species, which have some degree of fire tolerance, are at “increased risk of extinction.” These include shrubs and trees such as the granite boronia (Boronia granitica), Forrester’s bottlebrush (Callistemon forresterae), dwarf cypress pine (Callitris oblonga) and the Wolgan snow gum (Eucalyptus gregsoniana).
    Found, not lost
    Nevertheless, as researchers head out into the field to assess what’s lost, what they are sometimes finding are glimmers of hope. “Australian plants are remarkably resilient and there’s been regeneration in places where nobody thought there would be,” Gallagher says.
    One species that survived against all the odds is the Gibraltar Range waratah (Telopea aspera), a drought-resistant shrub with leathery leaves and bright red flowers. “This species has a very small range, being specialized to granite outcrops in one mountain range, which was burnt during the fires,” she says. “However, it has been noted as resprouting after the fires by park rangers and, in the absence of another fire in coming years, is likely to be able to recover.”
    Several animal species that were thought to be in grave peril following the fires that burned nearly half of the 4,400-square-kilometer Kangaroo Island have survived better than expected too (SN: 1/13/20). In the particularly badly burned reserves of the western end of the island, tiny marsupial carnivores called Kangaroo Island dunnarts (Sminthopsis aitkeni) are frequently appearing on camera traps. Swiftly erected predator-exclusion fences now protect survivors from feral cats.
    Tiny marsupials known as Kangaroo Island dunnarts (Sminthopsis aitkeni) have fared much better than other animals, appearing frequently on camera traps.Australian Wildlife Conservancy
    Similarly, large flocks of the glossy black-cockatoo (Calyptorhynchus lathami) have adapted by moving to unburned areas with food trees, says Karleah Berris of Natural Resources Kangaroo Island, who heads the crew that manages the endangered birds. Better news yet, a surprising number of birds bred and fledged young in mid-2020. “The important thing now is to protect what is left from fire until the burnt areas regenerate,” she says. “But I think, at present, all signs are that they are coping.”
    Hyman says that, hearteningly, her team found handfuls of survivors of some snail species during several surveys in New South Wales in late 2020. The snails turned up in small patches of unburned habitat, sometimes at the bottom of gullies or in deep leaf litter around the bases of large trees. And that gives her hope that other snail species may have held on in other, larger unburned patches with greater numbers of survivors.
    “But the question then becomes, what sort of recovery can they make from that?” she says. “Whether they can recover and breed up and start to move back into surviving areas again perhaps depends on how dry the weather is in coming years and if there are more fires.”
    She’s still hoping that a handful of Palethorpe’s pinwheel snails may have clung on against all the odds. “My husband is on tenterhooks wondering if his snail is still there or not,” she says. More

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    Some bacteria are suffocating sea stars, turning the animals to goo

    The mysterious culprit behind a deadly sea star disease is not an infection, as scientists once thought.
    Instead, multiple types of bacteria living within millimeters of sea stars’ skin deplete oxygen from the water and effectively suffocate the animals, researchers report January 6 in Frontiers in Microbiology. Such microbes thrive when there are high levels of organic matter in warm water and create a low oxygen environment that can make sea stars melt in a puddle of slime.
    Sea star wasting disease — which causes lethal symptoms like decaying tissue and loss of limbs — first gained notoriety in 2013 when sea stars living off the U.S. Pacific Coast died in massive numbers. Outbreaks of the disease had also occurred before 2013, but never at such a large scale.
    Scientists suspected that a virus or bacterium might be making sea stars sick. That hypothesis was supported in a 2014 study that found unhealthy animals may have been infected by a virus (SN: 11/19/14). But the link vanished when subsequent studies found no relationship between the virus and dying sea stars, leaving researchers perplexed (SN: 5/5/16). 

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    The new finding that a boom of nutrient-loving bacteria can drain oxygen from the water and cause wasting disease “challenges us to think that there might not always be a single pathogen or a smoking gun,” says Melissa Pespeni, a biologist at the University of Vermont in Burlington who was not involved in the work. Such a complex environmental scenario for killing sea stars “is a new kind of idea for [disease] transmission.”  
    There were certainly many red herrings during the hunt for why sea stars along North America’s Pacific Coast were melting into goo, says Ian Hewson, a marine biologist at Cornell University. In addition to the original hypothesis of a viral cause for sea star wasting disease — which Hewson’s team reported in 2014 in Proceedings of the National Academy of Sciences but later disproved — he and colleagues analyzed a range of other explanations, from differences in water temperature to exposing the animals to bacteria. But nothing reliably triggered wasting.   
    Then the researchers examined the types of bacteria living with healthy sea stars compared with those living among the animals with wasting disease. “That was when we had our aha moment,” says Hewson.
    Not all sea stars are susceptible to sea star wasting disease. Species that have more structures on their surface, and therefore more surface area for bacteria to deplete oxygen, appear more likely to get severely sick compared with flatter sea stars. In this photo, an ochre sea star (Pisaster ochraceus) succumbs to the disease in Davenport, Calif., in June 2018.Ian Hewson
    Types of bacteria known as copiotrophs, which thrive in environments with lots of nutrients, were present around the sea stars at higher levels than normal either shortly before the animals developed lesions or as they did so, Hewson and colleagues found. Bacterial species that survive only in environments with little to no oxygen were also thriving. In the lab, the sea stars began wasting when the researchers added phytoplankton or a common bacterial-growth ingredient to the warm water tubs those microbes and sea stars were living in.  
    Experimentally depleting oxygen from the water had a similar effect, causing lesions in 75 percent of the animals, while none succumbed in the control group. Sea stars breathe by diffusing oxygen over small external projections called skin gills, so the lack of oxygen in the wake of flourishing copiotrophs leaves sea stars struggling for air, the data show. It’s unclear how the animals degrade in low oxygen conditions, but it could be due to massive cell death.
    Although the disease isn’t caused by a contagious pathogen, it is transmissible in the sense that dying sea stars generate more organic matter that spur bacteria to grow on healthy animals nearby. “It’s a bit of a snowball effect,” Hewson says.
    The team also analyzed tissues from sea stars that had succumbed in the 2013 mass die-off — which followed a large algal bloom on the U.S. West Coast — to see if such environmental conditions might explain that outbreak. In fast-growing appendages that help them move, the sea stars that perished had high amounts of a form of nitrogen found in low oxygen conditions — a sign that those animals may have died from a lack of oxygen.
    The problem may get worse with climate change, Hewson says. “Warmer waters can’t have as much oxygen [compared with colder water] just by physics alone.” Bacteria, including copiotrophs, also flourish in warm water.  
    But pinpointing the likely cause could help experts better treat sick sea stars in the lab, Hewson says. Some techniques include increasing the oxygen levels in a water tank to make the gas more easily available to sea stars or getting rid of extra organic matter with ultraviolet light or water exchange.
    “There’s still a lot to figure out with this disease, but I think [this new study] gets us a long way to understanding how it comes about,” Pespeni says. More

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    Plastic waste forms huge, deadly masses in camel guts

    Marcus Eriksen was studying plastic pollution in the Arabian Gulf when he met camel expert Ulrich Wernery. “[Ulrich] said, ‘You want to see plastic? Come with me.’ So we went deep into the desert,” Eriksen recalls. Before long, they spotted a camel skeleton and began to dig through sand and bones.
    “We unearthed this mass of plastic, and I was just appalled. I couldn’t believe that — almost did not believe that — a mass as big as a medium-sized suitcase, all plastic bags, could be inside the rib cage of this [camel] carcass,” says Eriksen, an environmental scientist at the 5 Gyres Institute, a plastic pollution research and education organization in Santa Monica, Calif.
    “We hear about marine mammals, sea lions, whales, turtles and seabirds impacted” by plastic waste, Eriksen says (SN: 6/6/19). But “this is not just an ocean issue. It’s a land issue, too. It’s everywhere.”
    About 390,000 dromedary camels (Camelus dromedarius) live in the United Arab Emirates. Now in a study in the February 2021 Journal of Arid Environments, Eriksen, Wernery and colleagues estimate that plastic kills around 1 percent of these culturally important animals.
    Of 30,000 dead camels that Wernery, a veterinary microbiologist at the Central Veterinary Research Laboratory in Dubai, and his team have examined since 2008, 300 had guts packed with plastic ranging from three to 64 kilograms. The researchers dubbed these plastic masses “polybezoars” to distinguish them from naturally occurring hair and plant fiber bezoars.
    When camels eat plastic, it accumulates into enormous, stomach-clogging masses called polybezoars. Researchers found these polybezoars — the biggest of which weighs almost 64 kilograms — inside dead camels in the desert near Dubai.M. Eriksen et al/J. Arid Enviro. 2021
    When camels eat plastic, it accumulates into enormous, stomach-clogging masses called polybezoars. Researchers found these polybezoars — the biggest of which weighs almost 64 kilograms — inside dead camels in the desert near Dubai.M. Eriksen et al/J. Arid Enviro. 2021
    As dromedaries roam the desert looking for food, they munch on plastic bags and other trash that drift into trees and pile up along roadsides. “From the camel’s perspective … if it’s not sand, it’s food,” Eriksen says.
    With a stomach full of plastic, camels don’t eat because they don’t feel hungry, and they starve to death. Plastic can also leach toxins and introduce bacteria that poison the one-humped mammals, Wernery says.

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    “If 1 percent mortality due to plastic is verified by future and more detailed studies, then plastic pollution will certainly represent a reason of concern for [camels],” says Luca Nizzetto, an environmental scientist at the Norwegian Institute for Water Research in Oslo, who was not involved with the research. “These types of studies are relevant to raise social awareness about this pollution.”
    Banning plastic bags and single-use plastics is crucial for protecting camels and other wildlife, Eriksen says. “Plastic bags are escape artists. They blow out of garbage cans, out of landfills, out of trucks and out of people’s hands. They travel for hundreds of miles.” More

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    How frigid lizards falling from trees revealed the reptiles’ growing cold tolerance

    After the coldest night in south Florida in a decade, lizards were dropping out of palm trees, landing legs up. The scientists who raced to investigate the fallen reptiles have now found that, despite such graceless falls, some of these tropical, cold-blooded creatures are actually more resilient to cold than previously thought.
    The finding sheds light on how some species might respond to extreme weather events caused by human-caused climate change (SN: 12/10/19). Although climate change is expected to include gradual warming globally, scientists think that extreme events such as heat waves, cold snaps, droughts and torrential downpours could also grow in number and strength over time.
    The idea for the new study was born after evolutionary ecologist James Stroud received a photo of a roughly 60-centimeter-long iguana prone on its back on a sidewalk from a friend in Key Biscayne, an island town south of Miami. The previous night, temperatures dropped to just under 4.4° Celsius (40° Fahrenheit).
    “When air temperatures drop below a critical limit, lizards lose the ability to move,” says Stroud, of Washington University in St. Louis. Lizards that sleep in trees “may lose their grip.” Stunned lizards on the ground are likely easy prey for predators, he notes.

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    Realizing that the cold snap could be used to study how future instances of extreme weather might affect such animals in the wild, Stroud and colleagues rushed to collect live specimens of as many different kinds of lizards as they could in the Miami area (SN: 8/27/20). The researchers then tested how well the six reptile species they captured tolerated cold by sticking thermometers on the animals, placing them in a large cooler of ice and observing how cold they got before becoming too stunned to right themselves after getting flipped on their backs.
    Stroud and colleagues had previously run similar tests on these lizard species as part of research on invasive species. That work in 2016 suggested that the reptiles might not easily withstand cold snaps like the recent one — cold tolerances ranged from as low as about 7.7° C for the Puerto Rican crested anole (Anolis cristatellus) to roughly 11.1° C for the brown basilisk (Basiliscus vittatus).
    Some tropical, cold-blooded lizards, such as this brown basilisk (Basiliscus vittatus), are more resilient to cold than previously thought, a new study finds.John Sullivan/iNaturalist (CC BY-NC 4.0)
    The new study, however, revealed that the reptiles now could withstand temperatures roughly 1 to 4 degrees C colder. Oddly, the lizards, on average, could all endure cold down to the same lowest temperature, about 5.5° C, the researchers report in the October Biology Letters. Given the great variation in size, ecology and physiology between these species, “this was a really unexpected result,” and one that the researchers don’t have an explanation for, Stroud says.
    Natural selection may be behind the change, meaning that abnormally cold temperatures are killing off those individuals that could not survive and leaving behind those that happen to be better able to tolerate cold. Alternatively, the reptiles’ bodies could have changed in some way to acclimate to the colder temperatures. Stroud hopes in the future to measure the cold tolerance of lizards immediately before a forecasted cold snap and then examine the same reptiles immediately afterward to look for signs of acclimation.
    Scientists have long thought that tropical species, which have typically evolved in thermally stable environments, might prove especially vulnerable to major shifts in temperature (SN: 5/20/15). This new study reveals a way in which species can either rapidly evolve or acclimate, which “may provide ecosystems with some resilience to extreme climate events,” says Alex Pigot, an ecologist at University College London who did not take part in the research.
    One remaining question “is whether this resilience also applies to extreme heating events,” Pigot adds. “Previous evidence has suggested that species’ upper thermal limits may be less flexible than their lower thermal limits.” More

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    The diabolical ironclad beetle can survive getting run over by a car. Here’s how

    The diabolical ironclad beetle is like a tiny tank on six legs.
    This insect’s rugged exoskeleton is so tough that the beetle can survive getting run over by cars, and many would-be predators don’t stand a chance of cracking one open. Phloeodes diabolicus is basically nature’s jawbreaker.
    Analyses of microscope images, 3-D printed models and computer simulations of the beetle’s armor have now revealed the secrets to its strength. Tightly interlocked and impact-absorbing structures that connect pieces of the beetle’s exoskeleton help it survive enormous crushing forces, researchers report in the Oct. 22 Nature. Those features could inspire new, sturdier designs for things such as body armor, buildings, bridges and vehicles.
    The diabolical ironclad beetle, which dwells in desert regions of western North America, has a distinctly hard-to-squish shape. “Unlike a stink beetle, or a Namibian beetle, which is more rounded … it’s low to the ground [and] it’s flat on top,” says David Kisailus, a materials scientist at the University of California, Irvine. In compression experiments, Kisailus and colleagues found that the beetle could withstand around 39,000 times its own body weight. That would be like a person shouldering a stack of about 40 M1 Abrams battle tanks.
    Within the diabolical ironclad beetle’s own tanklike physique, two key microscopic features help it withstand crushing forces. The first is a series of connections between the top and bottom halves of the exoskeleton. “You can imagine the beetle’s exoskeleton almost like two halves of a clamshell sitting on top of each other,” Kisailus says. Ridges along the outer edges of the top and bottom latch together.
    This slice of a diabolical ironclad beetle’s back shows the jigsaw-shaped links that connect the left and right sides of its exoskeleton. These protrusions are tightly interlocked and highly damage-resistant, helping give the beetle its incredible durability.David Kisailus
    But those ridged connections have different shapes across the beetle’s body. Near the front of the beetle, around its vital organs, the ridges are highly interconnected — almost like zipper teeth. Those connections are stiff and resist bending under pressure.
    The connective ridges near the back of the beetle, on the other hand, are not as intricately interlocked, allowing the top and bottom halves of the exoskeleton to slide past each other slightly. That flexibility helps the beetle absorb compression in a region of its body that is safer to squish.
    The second key feature is a rigid joint, or suture, that runs the length of the beetle’s back and connects its left and right sides. A series of protrusions, called blades, fit together like jigsaw puzzle pieces to join the two sides. These blades contain layers of tissue glued together by proteins, and are highly damage-resistant. When the beetle is squashed, tiny cracks form in the protein glue between the layers of each blade. Those small, healable fractures allow the blades to absorb impacts without completely snapping, explains Jesus Rivera, an engineer at UC Irvine.

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    This toughness makes the diabolical ironclad beetle pretty predator-proof. An animal might be able to make a meal out of the beetle by swallowing it whole, Kisailus says. “But the way it’s built, in terms of other predation — let’s say like a bird that’s pecking at it, or a lizard that’s trying to chew on it — the exoskeleton would be really hard” to crack.
    That hard exterior is also a nuisance for insect collectors. The diabolical ironclad beetle is notorious among entomologists for being so fantastically durable that it bends the steel pins usually used to mount insects for display, says entomologist Michael Caterino of Clemson University in South Carolina. But “the basic biology of this thing is not particularly well-known,” he says. “I found it fascinating” to learn what makes the beetle so indestructible.
    The possibility of using beetle-inspired designs for sturdier airplanes and other structures is intriguing, Caterino adds. And with the splendid variety of insects all over the world, who knows what other critters might someday inspire clever engineering designs. More

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    Penguin poop spotted from space ups the tally of emperor penguin colonies

    Patches of penguin poop spotted in new high-resolution satellite images of Antarctica reveal a handful of small, previously overlooked emperor penguin colonies.
    Eight new colonies, plus three newly confirmed, brings the total to 61 — about 20 percent more colonies than thought, researchers report August 5 in Remote Sensing in Ecology and Conservation. That’s the good news, says Peter Fretwell, a geographer at the British Antarctic Survey in Cambridge, England.
    The bad news, he says, is that the new colonies tend to be in regions highly vulnerable to climate change, including a few out on the sea ice. One newly discovered group lives about 180 kilometers from shore, on sea ice ringing a shoaled iceberg. The study is the first to describe such offshore breeding sites for the penguins.

    Penguin guano shows up as a reddish-brown stain against white snow and ice (SN: 3/2/18). Before 2016, Fretwell and BAS penguin biologist Phil Trathan hunted for the telltale stains in images from NASA’s Landsat satellites, which have a resolution of 30 meters by 30 meters.
    Emperor penguins turned a ring of sea ice around an iceberg into a breeding site. The previously unknown colony was found near Ninnis Bank, a spot 180 kilometers offshore, thanks to a brown smudge (arrow) left by penguin poop.P.T. Fretwell and P.N. Trathan/Remote Sensing in Ecology and Conservation 2020
    The launch of the European Space Agency’s Sentinel satellites, with a much finer resolution of 10 meters by 10 meters, “makes us able to see things in much greater detail, and pick out much smaller things,” such as tinier patches of guano representing smaller colonies, Fretwell says. The new colony tally therefore ups the estimated emperor penguin population by only about 10 percent at most, or 55,000 birds.
    Unlike other penguins, emperors (Aptenodytes forsteri) live their entire lives at sea, foraging and breeding on the sea ice. That increases their vulnerability to future warming: Even moderate greenhouse gas emissions scenarios are projected to melt much of the fringing ice around Antarctica (SN: 4/30/20). Previous work has suggested this ice loss could decrease emperor penguin populations by about 31 percent over the next 60 years, an assessment that is shifting the birds’ conservation status from near threatened to vulnerable. More