CT scan of the front of a skate, showing the hard, tooth-like denticles (orange) on its skinYara Haridy Teeth first evolved as sensory organs, not for chewing, according to a new analysis of animal fossils. The first tooth-like structures seem to have been sensitive nodules on the skin of early fish that could detect changes in the surrounding water. The finding supports a long-standing idea that teeth first evolved outside the mouth, says Yara Haridy at the University of Chicago. Advertisement While there was some evidence to back this up, there was an obvious question. “What good is having all these teeth on the outside?” says Haridy. One possibility was that they served as defensive armour, but Haridy thinks there was more to it. “It’s great to cover yourself in hard things, but what if those hard things could also help you sense your environment?” True teeth are only found in backboned vertebrates, like fish and mammals. Some invertebrates have tooth-like structures, but the underlying tissues are completely different. This means teeth originated during the evolution of the earliest vertebrates: fish. Haridy and her team re-examined fossils that have been claimed to be the oldest examples of fish teeth, using a synchrotron to scan them in unprecedented detail. Unmissable news about our planet delivered straight to your inbox every month. Sign up to newsletter They focused first on fragmentary fossils of animals called Anatolepis, which date from the later part of the Cambrian Period, which ran from 539 million to 487 million years ago, and early in the Ordovician Period, which ran from 487 million to 443 million years ago. These animals had a hard exoskeleton, dotted with tubules. These had been interpreted as being tubules of dentine, one of the hard tissues that make up teeth. In human teeth, dentine is the yellow layer under the hard white enamel and it performs many functions, including sensing pressure, temperature and pain. This led to the idea that the tubules are precursors to teeth called odontodes and that Anatolepis is an early fish. That isn’t what Haridy and her team found. “We saw that the internal anatomy [of the tubules] didn’t actually look like a vertebrate at all,” she says. After examining structures from a range of animals, they found that the tubules were most similar to features called sensilla found on the exoskeletons of arthropods like insects and spiders. These look like pegs or small hairs and detect a range of phenomena. “It can be everything from taste to vibration to changes in air currents,” says Haridy. This means Anatolepis is an arthropod, not a fish, and its tubules aren’t the direct precursors to teeth. “Dentine is likely a vertebrate novelty, yet the sensory capabilities of a hardened external surface were present much earlier in invertebrates,” says Gareth Fraser at the University of Florida in Gainesville, who wasn’t involved in the study. With Anatolepis out of the picture, the team says, the oldest known teeth are those of Eriptychius, which is only known from the Ordovician Period. These do have true dentine – in odontodes on their skin. Haridy says invertebrates like Anatolepis and early vertebrates like Eriptychius independently evolved hard, sensory nodules on their skin. “These two very different animals needed to sense their way through the muck of ancient seas,” she says. In line with this, the team found that the odontodes on the skin of some modern fish still have nerves – suggesting a sensory function. Once some fish became active predators, they needed a way to hold onto their prey, so the hard odontodes made their way to the mouth, where they could be used to bite. “Based on the available data, tooth-like structures likely first evolved in the skin of early vertebrates, prior to the oral invasion of these structures that became teeth,” says Fraser. Journal reference:Nature DOI: 10.1038/s41586-025-08944-w Topics:

Teeth are sensitive because they evolved from sensory tissue in both ancient vertebrates and ancient arthropods.

shrinking Nemo Incredible shrinking clownfish beats the heat Shrinking down to size boosted clownfish survival rates up to 78 percent during heat waves. Jennifer Ouellette – May 21, 2025 2:00 pm | 7 Credit: Morgan Bennett-Smith Credit: Morgan Bennett-Smith Story text Size Small Standard Large Width * Standard Wide Links Standard Orange * Subscribers only   Learn more Pixar's Finding Nemo immortalized the colorful clownfish, with its distinctive orange body and white stripes, in the popular imagination. Clownfish, like many other species, are feeling the stress of rising temperatures and other environmental stressors. Fortunately, they have a superpower to cope: They can shrink their body size during dangerous heat waves to substantially boost their odds of survival, according to a new paper published in the journal Science Advances. “This is not just about getting skinnier under stressful conditions; these fish are actually getting shorter," said co-author Melissa Versteeg, a graduate student at Newcastle University. "We don’t know yet exactly how they do it, but we do know that a few other animals can do this too." Many vertebrates have shown growth decline in response to environmental stressors, especially higher temperatures. Marine iguanas, for example, reabsorb some of their bone material to shrink when their watery habitat gets warmer, while young salmon have been known to shrink at winter's onset. This can also happen when there is less food available. And social factors can also influence growth. When female meerkats, for example, are dominant, they have growth spurts, while a disruption in their social status can cause stunted growth in male cichlids What has been lacking in prior research is an investigation into how environmental and social factors interact to influence growth rates, according to Versteeg et al. They thought clownfish were the best species to study to fill that gap, since they've been extensively studied and are well understood. The fish live on Indo-Pacific coral reefs where heat stress has been increasing and has become more severe—an environment that is close to the thermal tolerance limits of clownfish. Clownfish also live in social groups: They form breeding pairs with a dominant female and subdominant male, sometimes adding subordinate non-breeding fish. The dominants tend to grow to match the size of the host anemone, while the subordinates only grow to a size that ensures there are sufficient resources—otherwise they risk being evicted and likely dying. Let’s get small The team observed 67 breeding pairs of wild clownfish—briefly caught and photographed for distinctive markings and measured before being returned to the water—living on single anemones in Kimbe Bay, Papua New Guinea, between February and August 2023. This happened to coincide with the world's fourth global bleaching event. They measured the body size of the fish once a month and measured the temperature around the individual anemones every four to six days. Then the team analyzed the collected data. "Individual fish can shrink in response to heat stress." Credit: Morgan Bennett-Smith The results: Over the course of those months, 101 of the 134 clownfish shrank at least once in response to heat stress, and doing so boosted their likelihood of survival up to 78 percent compared to the 33 fish that did not shrink. And between breeding pairs, there were distinctive growth ratios between the dominant and subordinate fish; those pairs that shrank together were also more likely to survive the heat waves. “We were so surprised to see shrinking in these fish that, to be sure, we measured each fish individual repeatedly over a period of five months," said Versteeg. "In the end, we discovered it was very common in this population. It was a surprise to see how rapidly clownfish can adapt to a changing environment, and we witnessed how flexibly they regulated their size, as individuals and as breeding pairs, in response to heat stress as a successful technique to help them survive.” Versteeg et al. have not yet identified a possible mechanism for the shrinkage, but suggest the triggering of neuroendocrine pathways via thyroid hormones might play a role, since those hormones regulate growth. The adaptive strategy could also be a means of adjusting to changing metabolic needs. But there are trade-offs: While shrinking in response to heat waves ensures greater survivability, there can also be a corresponding decrease in birth rates. "Our findings show that individual fish can shrink in response to heat stress, which is further impacted by social conflict, and that shrinking can lead to improving their chances of survival," said senior author Theresa Rueger, also of Newcastle University. "If individual shrinking were widespread and happening among different species of fish, it could provide a plausible alternative hypothesis for why the size of many fish species is declining, and further studies are needed in this area.” Science Advances, 2025. DOI: 10.1126/sciadv.adt7079  (About DOIs). Jennifer Ouellette Senior Writer Jennifer Ouellette Senior Writer Jennifer is a senior writer at Ars Technica with a particular focus on where science meets culture, covering everything from physics and related interdisciplinary topics to her favorite films and TV series. Jennifer lives in Baltimore with her spouse, physicist Sean M. Carroll, and their two cats, Ariel and Caliban. 7 Comments

I find it so ridiculous that there are still people who don’t believe in climate change. The effect on our environment has been so obvious the past few decades. We’re seeing so many unnatural weather conditions as well as the devastating impact it has had on natural coral reefs and vulnerable coastlines. This and natural disasters have affected the life and livelihood of people who live in areas near water. Miami is taking an innovative approach to combat climate change and protect its coastline: 3D-printed coral reefs. These artificial reefs are not just aesthetically interesting; they serve a crucial purpose in creating micro environments for marine life and acting as natural seawalls. The initiative, called the BIOCAP project, recognizes the significant threat climate change poses to natural coral reefs through rising sea temperatures and ocean acidification. These factors lead to coral bleaching and the degradation of vital marine ecosystems. To counter this, Florida International University (FIU) researchers led by Sara Pezeshk and Shahin Vassigh are designing and deploying intricate 3D-printed structures that mimic the complexity of natural reefs. Designer: Florida International University These artificial reefs are created using environmentally friendly materials and are carefully designed to provide the nooks and crannies that various marine species need for shelter, feeding, and reproduction. By offering a stable and suitable habitat, the 3D-printed reefs aim to attract and support a thriving community of fish, invertebrates, and other marine organisms. Beyond creating essential habitats, the artificial reefs also function as a form of natural coastal protection. Their complex structure helps to dissipate wave energy, acting as a buffer against erosion and storm surges. This is particularly important for low-lying coastal areas like Miami, which are increasingly vulnerable to the impacts of rising sea levels and more intense weather events. This project is a collaborative effort, bringing together expertise in marine biology, materials science, and 3D printing technology. This interdisciplinary approach is crucial for developing effective and sustainable solutions to the challenges posed by climate change. While 3D-printed reefs are not a complete replacement for natural coral reefs, which are incredibly complex and have evolved over millennia, they offer a promising tool for reef restoration and coastal protection in the face of environmental change. The project in Miami serves as an inspiring example of how human ingenuity and technology can be harnessed to address the urgent challenges of our time and contribute to the resilience of our planet’s vital ecosystems. As the project progresses, it will be crucial to monitor the long-term effectiveness of these artificial reefs and continue to refine their design and deployment for maximum ecological benefit. The post 3D-printed coral reefs can help protect coastline first appeared on Yanko Design.

Going for a stroll Carnivorous crocodile-like monsters used to terrorize the Caribbean While low sea levels helped sebecids spread, rising waters left them isolated. Elizabeth Rayne – May 16, 2025 1:10 pm | 21 Credit: By Ghedoghedo, CC BY-SA 3.0 Credit: By Ghedoghedo, CC BY-SA 3.0 Story text Size Small Standard Large Width * Standard Wide Links Standard Orange * Subscribers only   Learn more How did reptilian things that looked something like crocodiles get to the Caribbean islands from South America millions of years ago? They probably walked. The existence of any prehistoric apex predators in the islands of the Caribbean used to be doubted. While their absence would have probably made it even more of a paradise for prey animals, fossils unearthed in Cuba, Puerto Rico, and the Dominican Republic have revealed that these islands were crawling with monster crocodyliform species called sebecids, ancient relatives of crocodiles. While sebecids first emerged during the Cretaceous, this is the first evidence of them lurking outside South America during the Cenozoic epoch, which began 66 million years ago. An international team of researchers has found that these creatures would stalk and hunt in the Caribbean islands millions of years after similar predators went extinct on the South American mainland. Lower sea levels back then could have exposed enough land to walk across. “Adaptations to a terrestrial lifestyle documented for sebecids and the chronology of West Indian fossils strongly suggest that they reached the islands in the Eocene-Oligocene through transient land connections with South America or island hopping,” researchers said in a study recently published in Proceedings of the Royal Society B. Origin story During the late Eocene to early Oligocene periods of the mid-Cenozoic, about 34 million years ago, many terrestrial carnivores already roamed South America. Along with crocodyliform sebecids, these included enormous snakes, terror birds, and metatherians, which were monster marsupials. At this time, the sea levels were low, and the islands of the Eastern Caribbean are thought to have been connected to South America via a land bridge called GAARlandia (Greater Antilles and Aves Ridge). This is not the first land bridge to potentially provide a migration opportunity. Fragments of a single tooth unearthed in Seven Rivers, Jamaica, in 1999 are the oldest fossil evidence of a ziphodont crocodyliform (a group that includes sebecids) in the Caribbean. It was dated to about 47 million years ago, when Jamaica was connected to an extension of the North American continent known as the Nicaragua Rise. While the tooth from Seven Rivers is thought to have belonged to a ziphodont other than a sebacid, that and other vertebrate fossils found in Jamaica suggest parallels with ecosystems excavated from sites in the American South. The fossils found in areas like the US South that the ocean would otherwise separate suggest more than just related life forms. It's possible that the Nicaragua Rise provided a pathway for migration similar to the one sebecids probably used when they arrived in the Caribbean islands. Walking the walk So how did sebecids get from one land mass to the other on foot? They were made for it. Sebecids evolutionarily diverged from crocodiles during the Jurassic period. They had skulls similar to those of theropod dinosaurs, with a high rostrum (which holds the teeth along with the palate and nasal cavity) that was long and narrow. Their mouths were full of ziphodont teeth, which are compressed along the sides and have a serrated edge made for tearing flesh. Most important among the adaptations that made sebecids terrestrial animals were legs longer than their crocodilian brethren—legs made for walking on land. “Considering their terrestrial adaptations, their dispersal may have been either facilitated by some ephemeral terrestrial connection or string of large and closely spaced islands or occurred on a natural raft,” the research team said in the same study. Though they have been found across South America, earlier specimens of sebecids are best documented in the south of the continent, while later specimens surfaced in the north and tropical zones. Both the ziphodont teeth and concave vertebrae are found among the fossils found in the Dominican Republic, Cuba, and Puerto Rico, giving them away as sebecids. The locations of the fossils are consistent with the types of environments these carnivores were thought to inhabit as the Eocene gave way to the Oligocene. After they ended up in the Caribbean, the original population of sebecids eventually became isolated as sea levels rose, leaving the sub-populations on islands surrounded by water. The sebecids were apex predators in South America and are thought to have stayed at the top of the food chain in their new hunting grounds. Some sebecid remains have been found with fossils of terrestrial and semiaquatic vertebrates, such as sloths and turtles, that supposedly were their prey. Not only did sebecids get around, but they also lasted 5 million years longer in the Caribbean than they did in South America. This might have been because certain plant and animal species that died out on the mainland continued to survive on the islands. Crocodiles and predatory birds took over as apex predators after the sebecids died out. Even with a mouth full of knives, you can’t be at the top forever. Proceedings of the Royal Society B, 2025.  DOI: 10.1098/rspb.2024.2891 Elizabeth Rayne Elizabeth Rayne is a creature who writes. Her work has appeared on SYFY WIRE, Space.com, Live Science, Grunge, Den of Geek, and Forbidden Futures. She lurks right outside New York City with her parrot, Lestat. When not writing, she is either shapeshifting, drawing, or cosplaying as a character nobody has ever heard of. Follow her on Threads and Instagram @quothravenrayne. 21 Comments

May 15, 20253 min readNewly Discovered Fossil Tracks May Rewrite Early History of ReptilesFossilized claw tracks discovered in Australia show that the animal group that includes reptiles, mammals and birds formed earlier than expectedBy Rita Aksenfeld & Nature magazine Illustration of an amniote animal thought to have left fossilized claw prints in Victoria, Australia. Marcin AmbrozikFossil claw prints found in Australia were probably made by the earliest known members of the group that includes reptiles, birds and mammals, according to a study published in Nature today. The findings suggest that this group — the amniotes — originated at least 35 million years earlier than previously thought.Early amniotes evolved to lay eggs on land, because they were encased in an amniotic membrane that stopped them drying out. Before this study, the earliest known amniote fossils had been found in Nova Scotia, Canada, and were dated to the mid-Carboniferous period, about 319 million years ago. The latest findings suggest that amniotes also existed in the early Carboniferous period, around 355 million years ago.“This discovery is exciting, and if the tracks have been interpreted the right way, the findings have important implications for our understanding of tetrapod evolution,” says Steven Salisbury, a palaeontologist at the University of Queensland in Brisbane, Australia.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.The tracksThe claw tracks were found in a sandstone block on the bank of the Broken River at Barjarg in the state of Victoria, by two co-authors of the paper who are not professional scientists. This area of the river is known as Berrepit to the Indigenous Taungurung people who own the land.The sandstone block is part of a larger structure that had already been dated to the early Carboniferous on the basis of radiometric and tectonic evidence. Fossilized tracks of aquatic invertebrates and fish found in the same layer were also dated to this time period.The Snowy Plains Formation trackway slab with footprints and trackways highlighted. Manus (front foot) prints are shown in yellow; pes (hind foot) prints are shown in blue.Grzegorz NiedzwiedzkiThe three sets of tracks in the study have clear footprints with indentations from claws, a feature of reptiles but not of amphibians. “Having these hooked claws on the trackways indicates they’re definitely a reptile-like animal,” says John Long, a palaeontologist at Flinders University in Adelaide, Australia.There are no marks of dragging bellies or tails, and the authors suggest that the amniotes that left the tracks were able to keep their bodies and tails off the ground while they walked on land. But Salisbury questions that interpretation, because it would mean the animals had developed sophisticated structures for complex locomotion, which would be surprising given how early they are. “It seems more likely that the tracks were made by an animal that was ‘punting’ in shallow water, rather than walking on land,” he says.Common ancestorUntil now, evidence suggested that the last common ancestor of modern amphibians and amniotes lived around 352 million years ago. But if the ancestors of reptiles existed during the early Carboniferous, their split from amphibians must have occurred even earlier, says Long. Dating by the team suggests that the groups diverged in the Devonian period, about 380 million years ago.To estimate the probable time of divergence, Long and his colleagues used several dating methods. One included geological evidence from radioactive decay in volcanic rock layers above and below the fossil tracks. They also used molecular phylogenetics, which compares similarities and differences in the DNA of living species to estimate their evolutionary relationships and how recently their last common ancestor lived.The discovery could also shift the origin of amniotes to the Gondwana landmass. This formed the southern portion of the Pangaea supercontinent and gave rise to multiple current landmasses, including Africa and Australia. Previously, the earliest known amniotes were found in North America, leading palaeontologists to think that the group originated in the Northern Hemisphere. But more evidence from Australian fossils is needed before definitively shifting their origin site, says Long. “Australia is a vast area with fewer palaeontologists on the ground,” Long says. “We’ve got a lot more unexplored fossil sites where new things like this keep turning up.”This article is reproduced with permission and was first published on May 14, 2025.

Should you care about the suffering of bugs? For most people, it’s a laughable question. But for those who really, really care about animal welfare, there’s a certain intellectual journey that might lead them to take it seriously. It goes something like this: First, they learn that the vast majority of the 84 billion birds and mammals raised for food are kept on factory farms, where animals are routinely mutilated and intensively confined. They become passionate advocates for these neglected and abused creatures. Then they learn that over 90 percent of those land animals are poultry birds — chickens and turkeys raised for meat, and hens raised for eggs — who are treated worse than pigs and cows, and have even fewer legal protections. They become, more or less, advocates for chickens. But then they might learn that fish and shrimp are farmed (or caught from the ocean) on an even greater scale — trillions annually compared to a measly 76 billion chickens. If their compassion for animals extends equally to marine life, they might come to advocate primarily for these sea creatures. Go even further, and they’ll discover the emerging industry of insect farming, which works much like chicken, pig, or fish factory farming, with the aim of producing as many animals as possible as cheaply as possible. On these insect factory farms, vast numbers of bugs are confined in trays or other containers until, at several weeks old, they’re frozen, cooked, shredded, or suffocated alive. Most are then sold as feed for farmed fish, poultry, and pigs, as food for pets, or to a lesser degree, direct human consumption. For the animal advocates who take this journey and wind up at the bottom of this animal suffering rabbit hole, a new report from the research organization Rethink Priorities will be pure nightmare fuel. According to the group, humanity is on track to farm and kill nearly 6 trillion animals annually by 2033, a near-quadrupling from 2023. And almost all of the growth in animal farming will come from tiny animals: shrimp, fish, and most of all, two insect species (mealworms and black soldier fly larvae). While humans farm and slaughter an astonishing 3 billion pigs, sheep, goats, and cattle each year, these animals are so dwarfed in numbers by farmed chicken, fish, and bugs that Rethink Priorities didn’t even include them in its calculation, nor did it include the 1 to 2 trillion wild fish scooped out of the ocean every year. The forecast starkly illustrates how a transformation in global agriculture patterns have ratcheted up animal suffering to mind-boggling proportions. The reason is that we’re increasingly eating really small animals. In the 1990s, chicken overtook beef as America’s meat of choice, and US chicken consumption continues to climb every year. And it takes about 127 chickens to produce the same amount of meat as one cow, because cows are enormous, while chickens weigh only about 6 pounds at slaughter. So, as Americans shifted toward eating animal species that are smaller in size, the total number of animals raised on US factory farms shot up. The same logic applies to an even greater extent to fish and shrimp — you’d have to kill about 28,500 shrimps to get the same amount of meat as you would from one cow. These animals are being farmed and eaten in increasingly massive numbers around the world, with both fish and shrimp typically confined in crowded, disease-ridden ponds or tanks that animal advocates liken to underwater factory farms. The world now eats more fish from these farms than from the ocean. Even worse, small animals, like chickens, fish, insects, and shrimp, tend to be treated worse and have fewer protections than larger animals like pigs and cattle.Concern for the welfare of insects — and even fish and shrimp — might bemuse or even offend many people. Humans already kill untold numbers of bugs annually by simply going about our daily business — driving, walking, exterminating ant infestations from our homes, and spraying pesticides on our crops. Americans eat tens of billions of individual shrimps each year with virtually no worry that they might feel pain. While farmed chickens and pigs have received the sympathetic Hollywood treatment, like the Chicken Run movies, Charlotte’s Web, and Okja, similar films about shrimp or mealworms don’t seem to be in the offing. But Rethink Priorities, along with a growing chorus of scientists and philosophers, believe that invertebrates like shrimp and insects could be sentient, meaning they possess the capacity for pain, pleasure, and other sensations. They’re not arguing that these animals are equivalent to a chicken, cow, or human, but that they may be worth some moral consideration given emerging research on their potential for sentience and the massive scale on which they’re farmed.History has long shown us that today’s laughable moral concern could be tomorrow’s tragedy. That could be the case for these tiny, unfamiliar, uncharismatic animals the more we come to understand who they are and what they might be capable of feeling. What can a shrimp or an insect feel?There had long been relatively little research into whether invertebrates like shrimp and insects are sentient, but that’s begun to change in recent years.“Evidence is building that there’s a form of sentience there in insects,” Jonathan Birch, a philosopher at the London School of Economics who leads the Foundations of Animal Sentience project at the university, told me. Historically, this line of inquiry has focused on bees, he said, who have demonstrated signs of sentience by engaging in wound-tending behavior, complex decision-making in weighing pain versus pleasure, and even play. Some research has shown that fruit flies may have the capacity to feel pain and enjoy play.According to Birch and several of his colleagues, adult flies and mosquitoes, along with cockroaches and termites, satisfy six of eight key criteria for sentience, while several other orders satisfy three to four. He’s now collaborating with researchers to study pain indicators in black soldier fly larvae and crickets.What little research has looked at shrimp sentience has found mixed results, and much of it has been conducted on Caridean shrimp, not penaeid shrimp, the group that’s most commonly farmed (shrimp are not a single species, but a massive category comprising more than 2,000 known species across several taxonomic groups).Fish thrash inside a tightening net on a fish farm. Havva Zorlu/We AnimalsSome research has shown that shrimp have nociceptors, sensory neurons that detect and respond to potentially harmful stimuli — an important indicator of sentience — but their efforts to avoid threats could be merely reflexive. In one study, shrimp engaged in wound-tending behavior when researchers poured acid onto their antennae, but when they treated it with an anesthetic, the shrimp increased that behavior. This suggests they may not feel pain the way other animals do because the pain relief should have caused them to reduce wound tending.But Birch believes there is strong evidence of sentience in another crustacean species: the crab.Despite our limited understanding of invertebrates’ capacity for pain, our understanding of other animals’ capacities can quickly evolve. Just a couple of decades ago, it was largely thought that fish (which are not invertebrates) couldn’t feel pain, but scientific consensus has significantly shifted toward the belief that they can — and that they could experience many other physical and mental states. Given everything humans have learned about animals’ capacities in recent decades, there’s a strong argument to be made in favor of assuming that other animals are sentient unless proved otherwise, rather than assuming that they aren’t as the starting point.And if shrimp and insects are sentient, it would exacerbate an already emergency situation for global animal welfare, raising the number of farmed sentient animals by well over a trillion creatures today, and potentially many trillions in the decade ahead. The proposition to include these animals in humanity’s moral circle can lead some, Birch said, to throw up their hands in exasperation. “We lack ethical frameworks that tell us how to think about them, but to me, that’s not an excuse for ignoring the issue,” Birch said. “I think people sometimes imagine, well, if the sentient world is so vast — if all ways of feeding ourselves cause harm — then there can’t be any ethical constraints. And I think that’s entirely wrong. I think we do need to take the harm seriously, and think about what we might do to conduct ourselves more ethically.”A question of strategyMost people who advocate for factory-farmed animals focus on pigs, cows, chickens, and turkeys. Only the most quantitatively minded number-crunchers, like Birch and the folks at Rethink Priorities, look at the data and focus on fish, shrimp, and insects.Some in the animal advocacy movement might consider this expansion of moral concern — especially for insects — a major strategic error, one that will make an already fringe movement seem even more strange and scolding. It’s something, if I’m being honest, I’ve felt myself. A worker disinfects crickets’ watering trays in the final grow room at Entomo Farms in Ontario, Canada. James MacDonald/Bloomberg via Getty ImagesBut the general public might be more open to having some ethical consideration for these animals than we might think. Hannah McKay, a research analyst at Rethink Priorities who co-authored the new report, pointed me to recent surveys from the UK and Brazil in which a majority of participants said that they believed that shrimp can feel pain. In the UK and the Netherlands, food companies are phasing out particularly cruel practices in their shrimp supply chains, “even in the absence of high public pressure,” McKay said. Last month, a post about eyestalk ablation — the common, disturbing practice of tearing out female shrimp’s eyes to make them breed faster — made it to the front page of Reddit, whose users were overwhelmingly horrified by it.In 2022, the UK passed the Animal Welfare (Sentience) Act, which included decapod crustaceans (shrimp, lobsters, crabs, and crayfish) among the animals that should be considered sentient, in large part on the advice of Birch and colleagues.The aim of Rethink Priorities, Birch, and their ilk isn’t necessarily to start a campaign for worldwide shrimp and insect liberation, but rather to, at the very least, secure some minimum welfare standards.Many animal advocates today wish that their predecessors in the 1950s, who were more focused on the welfare of pets, had devoted more attention to cows, pigs, and chickens. Instead, the quiet rise of factory farming in mid-20th-century America went largely unchallenged, and has now led to the confinement, abuse, and slaughter of tens of billions of mammals and birds each year. Sagar Shah, a senior researcher at Rethink Priorities who co-authored the report with McKay, feels the same way about fish and shrimp farming, telling me that if he could turn the clock back 30 years to when these industries were relatively small, he would’ve pushed for “more resources into thinking about these questions: Are [fish and shrimp] sentient? What does good welfare mean for these animals if we’re going to use them?”“Collectively, we missed the boat a bit, and we’ve already got a huge scale of farming for fish and shrimp, and we’re catching up now,” Shah said. “But for insects, the industry is in its infancy, and that means we’ve got an opportunity to figure out what good welfare means and shape the growth of the industry.” It’s a cause that few animal advocates are willing to dedicate themselves to, and it may not win them many allies anytime soon. But that doesn’t deter Shah, who says “that doesn’t mean we shouldn’t try.” You’ve read 1 article in the last monthHere at Vox, we're unwavering in our commitment to covering the issues that matter most to you — threats to democracy, immigration, reproductive rights, the environment, and the rising polarization across this country.Our mission is to provide clear, accessible journalism that empowers you to stay informed and engaged in shaping our world. 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Watch a Giant Snail Lay an Egg From a Pore in Its Neck in First-Ever Footage Captured in New Zealand Conservation rangers took a video of an endangered, captive snail laying a large egg, revealing insight into the creature’s reproductive process Rangers witnessed a captive Powelliphanta augusta snail lay an egg from its neck, and they managed to catch it on video for the first time ever. New Zealand Department of Conservation A small, white orb emerges from the body of a slimy creature in footage shared by New Zealand’s Department of Conservation (DOC). Though this scene might not look like much, it’s an extremely rare moment that scientists just captured on video for the first time: a mysterious Powelliphanta augusta snail laying an egg from a pore in its neck. The snail is one of New Zealand’s most threatened invertebrates, named for its natural habitat along the Mount Augustus ridgeline in the country’s West Coast. But now, that site has almost entirely been destroyed by mining activity. To protect the snails, the DOC brought a number of them into captivity in 2006, and experts have been tending to the population ever since, keeping them in chilled containers that mimic the creature’s preferred environment. “It’s remarkable that in all the time we’ve spent caring for the snails, this is the first time we’ve seen one lay an egg,” DOC ranger Lisa Flanagan, who took the video, says in a statement. “We caught the action when we were weighing the snail. We turned it over to be weighed and saw the egg just starting to emerge from the snail.” Scientists knew very little about Powelliphanta snails before they began caring for the captive population. “This moment gives us a glimpse into the fascinating reproductive lives of these threatened snails,” according to a DOC Facebook post. Powelliphanta augusta snail laying an egg Watch on Powelliphanta are some of the largest snails in the world. They’re carnivorous, dwell on land and feast on worms and slugs. Like many other snails, they’re hermaphrodites, meaning individuals have both male and female genitalia. Powelliphanta snails thrive in moist habitats and are thus mostly found in New Zealand’s high-altitude forests and wetter western regions, where they occasionally emerge from leaf piles at night to mate and search for food. Many snails lay eggs, though some—like the marine species Littorina saxatilis—birth live baby snails, as reported by Live Science’s Pandora Dewan. The P. augusta snail, meanwhile, has a genital pore—akin to the vagina in mammals—just below its head. While this might seem like an unusual position, it allows the snail to poke out its head for mating and laying eggs, while the rest of its soft, vulnerable body remains protected by the shell. “It extends its penis out of this pore and into its mate’s pore, and its mate does the same, simultaneously exchanging sperm,” DOC senior science advisor Kath Walker explains in the statement. Though, as hermaphrodite “carnivores, which have to live at relatively low density, being able to occasionally self-fertilize must help with survival of the species.” What probably doesn’t help, however, is that P. augusta snails don’t reach sexual maturity until they’re 8 years old. While some of the snails in the DOC’s care are between 25 and 35 years old, they only lay about five eggs per year, which can take more than a year to hatch. That’s in stark contrast with non-native, invasive garden snails in New Zealand, which live short lives but lay thousands of eggs annually, according to the statement. When P. augusta’s habitat began to be threatened by mining in the early 2000s, the DOC relocated about 4,000 of them to other areas and took another 2,000 into captivity, per the Associated Press’ Charlotte Graham-McLay. It’s been a bumpy ride, however—the snails returned to the spotlight in 2011, when a faulty fridge accidentally froze 800 of them to death. “Keeping our wildlife in fridges is obviously not how New Zealanders would like to care for native animals found nowhere else in the world,” Nicola Toki, a conservationist who is now CEO of the New Zealand nonprofit Forest & Bird, told the BBC at the time. “It’s a sad fact that this has been the best option for them.” Nevertheless, the captive program has both saved the species from extinction and allowed scientists to learn more about the mysterious snail, per the DOC’s Facebook post. As reported by the Associated Press, the captive population had risen to 1,900 snails and almost 2,200 eggs by March of this year. Get the latest stories in your inbox every weekday.

An illustration of what the Amniote (early reptile) would look like from 350 million years ago. CREDIT: Martin Ambrozik. Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent every weekday. One of the most impactful stories in evolution is getting a rewrite, thanks to the exciting discovery of the earliest known set of reptile footprints. Craig A. Eury and John Eason, two amateur paleontologists exploring the fossil-rich Snowy Plains Formation in Australia, found a rock with an intriguing set of fossilized prints. They brought the intriguing specimen to professional paleontologists, who soon discovered that the roughly 356 million-year-old fossilized claw prints likely belong to an amniote–an early reptile relative.  Though small in stature, amniotes were a large evolutionary leap forward towards land-dwelling, four-limbed animals called tetrapods. The age of these prints suggest that amniotes evolved millions of years earlier than expected, according to a study published May 14 in the journal Nature.  “I’m stunned,” Per Ahlberg, a paleontologist at Uppsala University in Sweden who coordinated the study, said in a statement. “A single track-bearing slab, which one person can lift, calls into question everything we thought we knew about when modern tetrapods evolved.” When fish grew legs Tetrapods include all vertebrates with four limbs that primarily live on land, including everything from frogs to turtles to eagles, to tigers to humans. Their story began as fish left the water between 390 and 360 million years ago. Their descendants began to diversify into the ancestors of modern amphibians and amniotes–the group that includes birds, reptiles, and mammals. Originally, the timeline for how this massive diversification of life occurred was fairly clear-cut. The first tetrapods evolved roughly 390 million years ago during the Devonian period. Amniotoes and the earliest members of the modern groups of animals we see today followed fishapods during the Carboniferous period. Previously, the earliest amniote fossils dated back to  about 320 million years old to the late Carboniferous. Based on this new evidence, researchers concluded the start of the point on the evolutionary tree where the ancestors of amphibians and amniotes split actually happened in the earliest days of the Carboniferous or 356 million years ago.   Proof in the prints The newly discovered 356 million-year-old sandstone slab from this new study potentially changes this entire timeline by about 35 to 40 million years. The well-preserved footprints of long-toed feet with distinct claw impressions at the tips dot the stone and are the earliest known clawed footprints. Two sets of tracks were identified on the stone, seemingly from the same animal.  Footprints are important for paleontologists, as they can indicate the types of behaviors an extinct animal may have exhibited. The team compared the ancient tracks with a modern water monitor (Varanus salvator) lizard, since they have similarly shaped feet to what is seen on the footprints. They examined the spacing between the front and hind footprints against that living lizard’s feet. With these measurements, the team estimates that the ancient amniote may have been around 2.5 feet long, but that the exact proportions of the animal are still unknown. “Claws are present in all early amniotes, but almost never in other groups of tetrapods,” Ahlberg said. “The combination of the claw scratches and the shape of the feet suggests that the track maker was a primitive reptile.” If this new interpretation is correct, it pushes the origin of reptiles, and thus amniotes as a whole, back by roughly 40 million years to the earliest Carboniferous. A new set of fossil reptile footprints uncovered all the way across the globe in Poland are also detailed in the study and bolster the evidence. These European footprints are not as old as the ones from Australia, but are still older than previous specimens.  “The implications of this discovery for the early evolution of tetrapods are profound,” John Long, a study co-author and paleontologist at Flinders University in Australia, said. “All stem-tetrapod and stem-amniote lineages must have originated during the Devonian period – but tetrapod evolution proceeded much faster, and the Devonian tetrapod record is much less complete than we have believed.” A place on the evolutionary tree According to the team, this recalibration of the origin of reptiles has a ripple effect on the whole timeline of tetrapod evolution. Tetrapods must be older than even the earliest amniotes, since it has a deeper branching point on the evolutionary tree.  “It’s all about the relative length of different branches in the tree,” said Ahlberg. “In a family tree based on DNA data from living animals, branches will have different lengths reflecting the number of genetic changes along each branch segment. This does not depend on fossils, so it’s really helpful for studying phases of evolution with a poor fossil record.” The fossil trackways with the different tracks on it highlighted. CREDIT: Flinders University The team believes that amphibians and ammonites split apart further into the Devonian period and were likely a contemporary of the primitive, transitional “fishapod” called Tiktaalik. This evidence indicates that a diverse group of tetrapods existed when only transitional “fishapods” were believed to be dragging themselves around muddy shorelines and starting to explore the land.  If this new theory holds, it is likely that the evolution of tetrapods from aquatic creatures to those fully living on land may have occurred even faster than previously believed.   “The Australian footprint slab is about 50 cm [1.5 feet] across,” said Ahlberg, “and at present it represents the entire fossil record of tetrapods from the earliest Carboniferous of Gondwana – a gigantic supercontinent comprising Africa, South America, Antarctica, Australia and India. Who knows what else lived there?”   “The most interesting discoveries are yet to come and that there is still much to be found in the field,” added study co-author and paleontologist Grzegorz Niedźwiedzki. “These footprints from Australia are just one example of this.”