Comparison of a megalodon tooth and a great white shark tooth, not associated with the study. (Image Credit: Mark_Kostich/Shutterstock) NewsletterSign up for our email newsletter for the latest science newsMegalodon teeth have always been key to understanding the ancient marine predator. Fossilized teeth are all that remain to prove the existence of these massive sharks, and the name megalodon is from the Greek for “big tooth.”A new study, published in Earth and Planetary Science Letters, highlights the importance of the megalodon’s human-hand-sized teeth once again. Thanks to extracting and analyzing the traces of zinc left in the fossilized teeth, researchers now know that the megalodon’s diet was much broader than scientists once believed.“Megalodon was by all means flexible enough to feed on marine mammals and large fish, from the top of the food pyramid as well as lower levels – depending on availability,” said Jeremy McCormack from the Department of Geosciences at Goethe University, in a press release.What Did the Megalodon Eat?Clocking in at 78 feet in length and weighing about twice as much as a semi truck, the megalodon was a big fish with a big appetite. It is suggested that a member of the Otodus shark family would require about 100,000 kilocalories per day to survive. Due to this extreme number, scientists have often assumed that the megalodon’s main source of calories came from whales.This new study suggests that whales were not the only item on the megalodon’s daily menu and that these sharks were actually quite adaptable when it came to their food. The research team analyzed 18-million-year-old giant teeth that came from two fossil deposits in Sigmaringen and Passau. What they were looking for was the presence of zinc-66 and zinc-64, two isotopes commonly ingested with food. Typically, the higher up in a food pyramid an animal is, the lower the presence of zinc. As they are oftentimes at the top of the food chain, species such as Otodus megalodon and Otodus chubutensis have a low ratio of zinc-66 to zinc-64 compared to species lower on the food chain.“Sea bream, which fed on mussels, snails, and crustaceans, formed the lowest level of the food chain we studied,” said McCormack in the press release. “Smaller shark species such as requiem sharks and ancestors of today’s cetaceans, dolphins, and whales, were next. Larger sharks, such as sand tiger sharks, were further up the food pyramid, and at the top were giant sharks like Araloselachus cuspidatus and the Otodus sharks, which include megalodon.”Surprisingly, the zinc levels in the megalodon teeth weren’t always that different from the zinc levels in species lower down the food chain. This result means that the commonly held scientific belief that megalodons focused their attention on eating large marine mammals may be incorrect. Instead, McCormack refers to the megalodon as an “ecologically versatile generalist” that adapted to environmental and regional constraints that changed the availability and variety of their prey.A New Method in Teeth TestingUsing the zinc content of fossilized teeth is a relatively new method of analysis, and the research team working on the megalodon couldn’t be happier with their results. The methods used in this study have not only been used for prehistoric shark and whale species but also modern-day shark species, and have even been used on herbivorous prehistoric rhinoceroses.Overall, these new methods have begun to rewrite the history of megalodon’s eating habits and may help to explain more about why these giants of the food chain went extinct. “[Determining zinc isotope ratios] gives us important insights into how the marine communities have changed over geologic time, but more importantly the fact that even ‘supercarnivores’ are not immune to extinction,” said Kenshu Shimada, a paleobiologist at DePaul University and a coauthor of this study, in the press release.Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:Earth and Planetary Science Letters. Miocene marine vertebrate trophic ecology reveals megatooth sharks as opportunistic supercarnivoresAs the marketing coordinator at Discover Magazine, Stephanie Edwards interacts with readers across Discover's social media channels and writes digital content. Offline, she is a contract lecturer in English & Cultural Studies at Lakehead University, teaching courses on everything from professional communication to Taylor Swift, and received her graduate degrees in the same department from McMaster University. You can find more of her science writing in Lab Manager and her short fiction in anthologies and literary magazine across the horror genre.1 free article leftWant More? Get unlimited access for as low as $1.99/monthSubscribeAlready a subscriber?Register or Log In1 free articleSubscribeWant more?Keep reading for as low as $1.99!SubscribeAlready a subscriber?Register or Log In

James Gentz has seen birds aplenty on his East Texas rice-and-crawfish farm: snow geese and pintails, spoonbills and teal. The whooping crane couple, though, he found “magnificent.” These endangered, long-necked behemoths arrived in 2021 and set to building a nest amid his flooded fields. “I just loved to see them,” Gentz says. Not every farmer is thrilled to host birds. Some worry about the spread of avian flu, others are concerned that the birds will eat too much of their valuable crops. But as an unstable climate delivers too little water, careening temperatures and chaotic storms, the fates of human food production and birds are ever more linked—with the same climate anomalies that harm birds hurting agriculture too. In some places, farmer cooperation is critical to the continued existence of whooping cranes and other wetland-dependent waterbird species, close to one-third of which are experiencing declines. Numbers of waterfowl (think ducks and geese) have crashed by 20 percent since 2014, and long-legged wading shorebirds like sandpipers have suffered steep population losses. Conservation-minded biologists, nonprofits, government agencies, and farmers themselves are amping up efforts to ensure that each species survives and thrives. With federal support in the crosshairs of the Trump administration, their work is more important (and threatened) than ever. Their collaborations, be they domestic or international, are highly specific, because different regions support different kinds of agriculture—grasslands, or deep or shallow wetlands, for example, favored by different kinds of birds. Key to the efforts is making it financially worthwhile for farmers to keep—or tweak—practices to meet bird forage and habitat needs. Traditional crawfish-and-rice farms in Louisiana, as well as in Gentz’s corner of Texas, mimic natural freshwater wetlands that are being lost to saltwater intrusion from sea level rise. Rice grows in fields that are flooded to keep weeds down; fields are drained for harvest by fall. They are then re-flooded to cover crawfish burrowed in the mud; these are harvested in early spring—and the cycle begins again. That second flooding coincides with fall migration—a genetic and learned behavior that determines where birds fly and when—and it lures massive numbers of egrets, herons, bitterns, and storks that dine on the crustaceans as well as on tadpoles, fish, and insects in the water. On a biodiverse crawfish-and-rice farm, “you can see 30, 40, 50 species of birds, amphibians, reptiles, everything,” says Elijah Wojohn, a shorebird conservation biologist at nonprofit Manomet Conservation Sciences in Massachusetts. In contrast, if farmers switch to less water-intensive corn and soybean production in response to climate pressures, “you’ll see raccoons, deer, crows, that’s about it.” Wojohn often relies on word-of-mouth to hook farmers on conservation; one learned to spot whimbrel, with their large, curved bills, got “fired up” about them and told all his farmer friends. Such farmer-to-farmer dialogue is how you change things among this sometimes change-averse group, Wojohn says. In the Mississippi Delta and in California, where rice is generally grown without crustaceans, conservation organizations like Ducks Unlimited have long boosted farmers’ income and staying power by helping them get paid to flood fields in winter for hunters. This attracts overwintering ducks and geese—considered an extra “crop”—that gobble leftover rice and pond plants; the birds also help to decompose rice stalks so farmers don’t have to remove them. Ducks Unlimited’s goal is simple, says director of conservation innovation Scott Manley: Keep rice farmers farming rice. This is especially important as a changing climate makes that harder. 2024 saw a huge push, with the organization conserving 1 million acres for waterfowl. Some strategies can backfire. In Central New York, where dwindling winter ice has seen waterfowl lingering past their habitual migration times, wildlife managers and land trusts are buying less productive farmland to plant with native grasses; these give migratory fuel to ducks when not much else is growing. But there’s potential for this to produce too many birds for the land available back in their breeding areas, says Andrew Dixon, director of science and conservation at the Mohamed Bin Zayed Raptor Conservation Fund in Abu Dhabi, and coauthor of an article about the genetics of bird migration in the 2024 Annual Review of Animal Biosciences. This can damage ecosystems meant to serve them. Recently, conservation efforts spanning continents and thousands of miles have sprung up. One seeks to protect buff-breasted sandpipers. As they migrate 18,000 miles to and from the High Arctic where they nest, the birds experience extreme hunger—hyperphagia—that compels them to voraciously devour insects in short grasses where the bugs proliferate. But many stops along the birds’ round-trip route are threatened. There are water shortages affecting agriculture in Texas, where the birds forage at turf grass farms; grassland loss and degradation in Paraguay; and in Colombia, conversion of forage lands to exotic grasses and rice paddies these birds cannot use. Conservationists say it’s critical to protect habitat for “buffies” all along their route, and to ensure that the winters these small shorebirds spend around Uruguay’s coastal lagoons are a food fiesta. To that end, Manomet conservation specialist Joaquín Aldabe, in partnership with Uruguay’s agriculture ministry, has so far taught 40 local ranchers how to improve their cattle grazing practices. Rotationally moving the animals from pasture to pasture means grasses stay the right length for insects to flourish. There are no easy fixes in the North American northwest, where bird conservation is in crisis. Extreme drought is causing breeding grounds, molting spots, and migration stopover sites to vanish. It is also endangering the livelihoods of farmers, who feel the push to sell land to developers. From Southern Oregon to Central California, conservation allies have provided monetary incentives for water-strapped grain farmers to leave behind harvest debris to improve survivability for the 1 billion birds that pass through every year, and for ranchers to flood-irrigate unused pastures. One treacherous leg of the northwest migration route is the parched Klamath Basin of Oregon and California. For three recent years, “we saw no migrating birds. I mean, the peak count was zero,” says John Vradenburg, supervisory biologist of the Klamath Basin National Wildlife Refuge Complex. He and myriad private, public, and Indigenous partners are working to conjure more water for the basin’s human and avian denizens, as perennial wetlands become seasonal wetlands, seasonal wetlands transition to temporary wetlands, and temporary wetlands turn to arid lands. Taking down four power dams and one levee has stretched the Klamath River’s water across the landscape, creating new streams and connecting farm fields to long-separated wetlands. But making the most of this requires expansive thinking. Wetland restoration—now endangered by loss of funding from the current administration—would help drought-afflicted farmers by keeping water tables high. But what if farmers could also receive extra money for their businesses via eco-credits, akin to carbon credits, for the work those wetlands do to filter-clean farm runoff? And what if wetlands could function as aquaculture incubators for juvenile fish, before stocking rivers? Klamath tribes are invested in restoring endangered c’waam and koptu sucker fish, and this could help them achieve that goal. As birds’ traditional resting and nesting spots become inhospitable, a more sobering question is whether improvements can happen rapidly enough. The blistering pace of climate change gives little chance for species to genetically adapt, although some are changing their behaviors. That means that the work of conservationists to find and secure adequate, supportive farmland and rangeland as the birds seek out new routes has become a sprint against time. This story originally appeared at Knowable Magazine. Lela Nargi, Knowable Magazine Knowable Magazine explores the real-world significance of scholarly work through a journalistic lens. 0 Comments

This Deposit of ‘Weird’ Cretaceous Amber Could Reveal Hints to Long-Forgotten Tsunamis in Japan A new study highlights the potential of amber fossils to capture evidence of powerful, prehistoric ocean waves A tsunami might have occured some 115 million years ago, near where deposits of Cretaceous amber were found in Japan. Wikimedia Commons under CC0 1.0 Scientists in Japan have uncovered amber deposits that may hold elusive evidence of tsunamis that occurred between 114 million and 116 million years ago. Their findings were published in the journal Scientific Reports last week. The researchers stumbled upon the amber—fossilized tree resin—by chance while collecting rocks from a sand mine in Hokkaido, an island in northern Japan. The deposit would have been on the seafloor when it was formed during the Cretaceous period. “We found a weird form of amber,” says lead author Aya Kubota, a geologist at the National Institute of Advanced Industrial Science and Technology in Japan, to Katherine Kornei at Science News. The scientists analyzed the resin with a technique called fluorescence imaging, in which they snapped photos of the remains under ultraviolet light. This helped them see how the amber was separated by layers of dark sediment, creating shapes known as “flame structures.” The unusual pattern arises when soft amber deforms before completely hardening. “Generally, they will form when a denser layer gets deposited on top of a softer layer,” says Carrie Garrison-Laney, a geologist at Washington Sea Grant who was not involved in the study, to Science News. The researchers suggest this is evidence that the resin rapidly traveled from land while it was still malleable and solidified underwater. A tsunami could be what swept the trees from land to the ocean so quickly, the study authors write. If true, this could offer scientists a potential new technique for finding prehistoric tsunamis. “Identifying tsunamis is generally challenging,” Kubota explains to Live Science’s Olivia Ferrari in an email. Tsunami deposits are easily eroded by the environment, and they can also be hard to distinguish from deposits caused by other storms. But in this case, “by combining detailed field observations with the internal structures of amber, we were able to conclude that the most plausible cause was tsunamis.” Cretaceous amber deposits (a, b, d, e) and fossilized driftwood (c) examined in the study Kubota, Aya et al., Scientific Reports, 2025, under CC BY-NC-ND 4.0 Other evidence also bolsters the researchers’ conclusion: A massive, nearby landslide offers a sign that an earthquake may have occurred around the same time the amber formed, and displaced mud and tree trunks were found in the same sediments—all signs of a violent tsunami. The trunks didn’t show any signs of erosion by shallow water-dwelling marine creatures, suggesting they were carried quickly out to sea. The vegetation found in the fossil deposit suggests multiple tsunamis occurred within the span of two million years, reports Hannah Richter for Science. But Garrison-Laney tells Science News that more evidence is needed to prove the amber is linked to a tsunami. She’s not sure the Cretaceous tree resin would have stayed soft once it hit the cold ocean water. “That seems like a stretch to me,” she tells the publication, adding that research on more of the area’s amber deposit will be needed to confirm the findings. With further study, scientists could use amber-rich sediments as a way to identify tsunamis throughout history. “Resin offers a rare, time-sensitive snapshot of depositional processes,” Kubota tells Live Science. Previously, scientists have found tiny crustaceans, prehistoric mollusks and even hell ants encased in the orangey resin, a window into worlds past. Now, “the emerging concept of ‘amber sedimentology’ holds exciting potential to provide unique insights into sedimentological processes,” Kubota adds to Live Science. Get the latest stories in your inbox every weekday. More about: Fossils Japan New Research Oceans Tsunami

Alicella gigantea, the world’s largest amphipod, may be more common than we had thoughtMaroni et al./Royal Society Open Science A giant crustacean that resembles a large white shrimp may be far more common across the deep sea than thought, with potential habitat extending over much of the ocean floor. “We have called this species rare for so long. We call everything in the deep sea rare,” says Paige Maroni at the University of Western Australia. “But in actual fact these species are probably more connected than we would have ever expected.” Advertisement The crustacean, known as Alicella gigantea, has the distinction of being the world’s largest amphipod, growing up to 34 centimetres in length. But this “supergiant”, living on the floor of the deep ocean, hasn’t been easy to find. “Because [the deep sea] is so hard to get to, it’s been undersampled for so long, and we’re finally playing catch up,” says Maroni. She and her colleagues collected 75 records of A. gigantea, stretching back to the first collection of a specimen in 1899. These included finds in the Pacific, Atlantic and Indian oceans. They also used DNA sequences from specimens across all three oceans to reconstruct genetic relationships among different populations. They found the specimens had been collected from depths ranging from 3890 to 8931 metres. They estimate that about 59 per cent of the sea floor falls within this range. The genetic data also suggested the specimens, although distributed across this vast area, all represented one genetically similar species. Unmissable news about our planet delivered straight to your inbox every month. Sign up to newsletter Maroni says this implies the crustaceans could live across far more of the ocean floor than sparse collections would suggest. The 59 per cent figure based only on depth is a maximum habitat extent, but is the best available based on the little we know about these creatures. Journal referenceRoyal Society Open Science DOI: 10.1098/rsos.241635 Topics:

Sharks don’t have bones. Instead, their skeletons are made from mineralized cartilage that helps them constantly move through water. To understand the internal “sharkitecture” that helps keep these animals strong and graceful, researchers are putting sharks under the microscope. A new study, published in ACS Nano, found some surprising results. After analyzing shark cartilage, there appear to be two different regions within it. And each appears to have vastly different structures. These structures have shown a resistance to destruction and could inspire strong, flexible materials for the future. Analyzing a Shark Skeleton An X-ray nanotomography reconstruction of the intermedial cartilage of a blacktip shark. The colors indicate the thickness of the struts, with red representing thicker areas and blue indicating thinner ones. (Image Credit: Florida Atlantic University)Sharks are powerful and efficient creatures. Thanks to their skeletal frame, made of mineralized cartilage, their spines can act like a spring, which stores and releases energy as they move their tails, according to a press release. Wanting to better understand how this cartilage helps keep sharks atop the ocean’s food chain, researchers from the Charles E. Schmidt College of Science and the College of Engineering and Computer Science at Florida Atlantic University (FAU), in collaboration with the German Electron Synchrotron (DESY) in Germany, and NOAA Fisheries, have analyzed blacktip sharks (Carcharhinus limbatus) and mapped out their internal structure. The team used synchrotron X-ray nanotomography with detailed 3D imaging and in-situ mechanical testing to create the map. The results showed that on a nano level, the blacktip shark’s cartilage had two distinct regions, the corpus calcareum and the intermediale. Though both of these regions are made up of densely packed collagen and bioapatite, they have vastly different internal structures. Strong Microscopic Structures According to the study, in each region, the cartilage is porous and also has thick struts that help the skeleton with strain from multiple directions. This is a key adaptation as sharks are continuously moving and putting pressure on their spines.  Researchers also found microscopic needle-like bioapatite crystals, similar to those in human bones, that were lined up with strands of collagen. This is another factor that gives shark cartilage extra strength and flexibility. Along with that, the research team also noted helical fiber structures, also with collagen, which suggests the cartilage is designed to prevent any cracks from spreading, and help to distribute staring and force. “Nature builds remarkably strong materials by combining minerals with biological polymers, such as collagen – a process known as biomineralization. This strategy allows creatures like shrimp, crustaceans, and even humans to develop tough, resilient skeletons,” said Vivian Merk, senior study author and an assistant professor in the FAU Department of Chemistry and Biochemistry, in a press release.“Sharks are a striking example. Their mineral-reinforced spines work like springs, flexing and storing energy as they swim. By learning how they build such tough yet adaptable skeletons, we hope to inspire the design of next-generation materials,” Merk added in the release. Shark Inspiration for MaterialsThe research team applied pressure to microscopic pieces of the shark’s vertebrae and found deformations, smaller than one micrometer. The team only noticed fractures in the vertebrae after a second round of pressure was applied. But even then, the fractures were only found within one mineralized plane, proving how strong the material was. “After hundreds of millions of years of evolution, we can now finally see how shark cartilage works at the nanoscale – and learn from them,” said Marianne Porter, study co-author and an associate professor in the FAU Department of Biological Sciences, in a press release. “We’re discovering how tiny mineral structures and collagen fibers come together to create a material that’s both strong and flexible, perfectly adapted for a shark’s powerful swimming. These insights could help us design better materials by following nature’s blueprint,” Porter added in the release.Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:A graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.

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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Nature, Published online: 13 May 2025; doi:10.1038/d41586-025-01342-2The interstellar origins of space’s dirty snowballs, and debunking a myth about maternal crustaceans, in our weekly dip into Nature’s archive.