During a severe heat wave in 2023, scientists scuba diving off the coast of Papua New Guinea captured clownfish to measure their bodies. Between February and August, they calculated the length of 134 of these iconic, orange and white fish once a month, taking a total of six measurements for each fish.Those measurements revealed something peculiar: Most of the fish shrank.This week, the researchers reported their findings in Science Advances, concluding that the fish got shorter — on the scale of a few millimeters, or a small, single-digit percent of their length — in response to the heat wave.Morgan Bennett-Smith“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 Melissa Versteeg, a doctoral researcher at Newcastle University, who led the study in collaboration with Mahonia Na Dari, an environmental organization, and Walindi Resort. “In the end, we discovered [that downsizing] was very common in this population.”Versteeg and her colleagues don’t know how, exactly, the fish are shrinking — one untested idea is that the fish might be reabsorbing some of their bone material or tissue. But getting smaller isn’t a problem. In fact, the study found, it may be an adaptation to help clownfish survive hotter ocean temperatures.Morgan Bennett-SmithWhen it’s good to be smallLast year, the planet was about 2.65 degrees warmer than it was in the late 1800s. This level of warming impacts wild animals in a number of strange, mostly bad, ways, from fueling koala-killing wildfires to causing corals to bleach and then starve.But rising temperatures also appear to be making many species smaller. One especially striking study, published in 2019, found that birds shrank by an average of about 2.6 percent between 1978 and 2016. More recent analyses have linked rising temperatures to a reduction in body size of small mammals in North America and marine fish. Most of these existing studies report that animals, on average, are simply not growing as large.The new study on clownfish, however, suggests individual fish are shrinking over mere weeks in response to a heat wave, which, in the case of the Papua New Guinea event, pushed temperatures in the bay about 7 degrees (4 degrees Celsius) above average.Why do they do this?Being tiny has its advantages in a hot climate: Warm-blooded animals, like mammals, shed heat more easily when they’re small and this helps them cool down. The benefits for cold-blooded creatures, such as clownfish, aren’t as clear, though researchers think they may have an easier time meeting their bodies’ energy requirements when they’re small.Morgan Bennett-SmithRegardless of the reason, being small seems to help clownfish when it’s hot. The fish that shrank, the study found, had a much higher chance of surviving.“It was a surprise to see how rapidly clownfish can adapt to a changing environment,” Versteeg said. “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.”The study adds a layer of complexity to what is otherwise a depressing tale about the world’s oceans. Heat waves linked to climate change, like the one that occurred during this study, are utterly devastating coral reefs — and in severe cases, are nearly wiping out entire reef sections. These colorful ecosystems are home to countless marine animals, including those we eat, like snappers, and clownfish.Amid that loss, animals are proving highly resilient. They’re trying hard to hold on. Yet if warming continues, even the best adaptations may not be enough.See More:

Clownfish Shrink Down Their Bodies to Survive Ocean Heat Waves, New Study Suggests The adaptation appears to help the fish cope with high temperatures, since individuals and breeding pairs that shrank improved their survival odds Clownfish seem to become shorter during heat waves, according to the new study. Morgan Bennett-Smith A new study reveals that clownfish use a surprising strategy to adapt their bodies to ocean heat waves: They shrink. “[Clownfish] have these amazing abilities that we still don’t know all that much about,” says study co-author Theresa Rueger, a tropical marine ecologist at Newcastle University in England, to the Washington Post’s Dino Grandoni. The findings offer some hope for fish in the face of climate change, she adds. “There’s potential that maybe some other species will adapt in a way that will allow them to hang on longer than we think.” Rueger and her team didn’t initially plan to study a heat wave. They were monitoring how freshwater runoff might affect breeding clownfish in Papua New Guinea’s Kimbe Bay, when temperatures dramatically rose and warmed the water to 7.2 degrees Fahrenheit above average. But these conditions, they realized, offered a key opportunity for research. The scientists measured 134 clownfish in Kimbe Bay every month during the ocean heat wave, which spanned from February to August 2023. Astoundingly, 100 of those fish shrank. The researchers found that 71 percent of the dominant females and 79 percent of the breeding males reduced in size at least once over the study period. Their findings were published in the journal Science Advances on Wednesday. At first, lead author Melissa Versteeg, a PhD researcher at England’s Newcastle University, thought she was making a mistake in her measurements. She kept trying again. And again. “She had several people measuring them at the same time to really make sure that we’re confident with the numbers,” Rueger says to Melissa Hobson at National Geographic. But after these repeated attempts, she concluded the measurements were correct. The fish that shrank increased their chances of surviving the heat wave by 78 percent, according to the study. Some of the clownfish even shrank in pairs, reducing their size alongside their breeding partner—a move that also boosted their chance of survival. The study marks the first time a coral reef-dwelling fish has been documented to shrink in response to environmental and social cues, according to a statement from Newcastle University. A pair of clownfish swims near an anemone. When the studied fish became smaller, females maintained a larger size than males. Morgan Bennett-Smith Clownfish aren’t the only animals shifting their size because of heat. Fish around the world are adapting to warmer temperatures by downsizing their bodies. “This is another tool in the toolbox that fish are going to use to deal with a changing world,” says Simon Thorrold, an ocean ecologist at Woods Hole Oceanographic Institution who was not involved in the new work, to Adithi Ramakrishnan at the Associated Press. But these clownfish stand out from the rest. “Until now, when talking about shrinking fish, nearly all studies do not mean that fish literally shrink but that they grow to smaller sizes,” explains Asta Audzijonyte, a senior lecturer at the University of Tasmania in Australia who was not involved in the work, to the Washington Post. “This study, in contrast, reports observations of [clownfish] actually shrinking by a few percent of their total length over the course of a month.” Previous research has found that other animals, like birds and rodents, appear to have gotten smaller because of climate change. And marine iguanas will shrink in response to warmer water temperatures during El Niño years. The researchers don’t yet know how the clownfish are pulling off their shrinking act. One hypothesis is that the fish are reabsorbing their own bone matter, reports the Associated Press. They’re also not sure why, exactly, changing size is so advantageous to the clownfish. But it could be that a smaller size makes it easier to maintain oxygen levels or get by with less food available. “If you’re small, you obviously need less food, and you’re also more efficient in foraging a lot of the time,” explains Rueger to National Geographic. Still, this adaptation method can only go so far. The heat wave exacerbated coral bleaching, which decreases available reef habitat, and subsequent heat waves ultimately killed many of the fish the researchers studied. “We’ve lost many of those fish,” Rueger says to the Washington Post. Get the latest stories in your inbox every weekday.

By Passant Rabie Published May 13, 2025 | Comments (1) | An illustration of a decaying neutron star. Daniëlle Futselaar/artsource.nl Around 13.8 billion years ago, a tiny but dense fireball gave birth to the vast cosmos that holds trillions of galaxies, including the Milky Way. But our universe is dying, and it’s happening at a much faster rate than scientists previously estimated, according to new research. The last stellar remnants of the universe will cease to exist in 10 to the power of 78 years (that’s a one with 78 zeros), according to a new estimate from a group of scientists at Radboud University in the Netherlands. That’s still a long way off from when the universe powers down for good—but it’s a far earlier fade-to-black moment than the previous 10 to the power of 1,100 years estimate. The new paper, published Monday in the Journal of Cosmology and Astroparticle Physics, is a follow-up to a previous study by the same group of researchers. In their 2023 study, black hole expert Heino Falcke, quantum physicist Michael Wondrak, and mathematician Walter van Suijlekom suggested that other objects, like neutron stars, could evaporate in much the same way as black holes. The original theory, developed by Stephen Hawking in 1974, proposed that radiation escaping near a black hole’s event horizon would gradually erode its mass over time. The phenomenon, known as Hawking radiation, remains one of the most surprising ideas about black holes to this day. Building on the theory of Hawking radiation, the researchers behind the new paper suggest that the process of erosion depends on the density of the object. They found that neutron stars and stellar black holes take roughly the same amount of time to decay, an estimated 10 to the power of 67 years. Although black holes have a stronger gravitational field that should cause them to evaporate faster, they also have no surface so they end up reabsorbing some of their own radiation, “which inhibits the process,” Wondrak said in a statement. The researchers then calculated how long various celestial bodies would take to evaporate via Hawking-like radiation, leading them to the abbreviated cosmic expiration date. “So the ultimate end of the universe comes much sooner than expected, but fortunately it still takes a very long time,” Falcke said. The study also estimates that it would take the Moon around 10 to the power of 90 years to evaporate based on Hawking radiation. “By asking these kinds of questions and looking at extreme cases, we want to better understand the theory, and perhaps one day, we unravel the mystery of Hawking radiation,” van Suijlekom said. Daily Newsletter You May Also Like By Isaac Schultz Published May 11, 2025 By Passant Rabie Published March 20, 2025 By Passant Rabie Published February 10, 2025 By Isaac Schultz Published February 2, 2025 By Margherita Bassi Published February 1, 2025 By Isaac Schultz Published January 28, 2025