Photo credit: Representative Cover Image Source: The ‘Licorne’ French nuclear test explosion at Fangataufa Atoll in French Polynesia, 3rd July 1970.(Photo by Ann Ronan Pictures/Print Collector/Getty Images) – Array
Over the years, films like “2012” and “Mad Max” have imagined how humans might survive an apocalypse. While scientists have ruled out the possibility of human life thriving in a post-apocalyptic world, they’ve found that one tiny creature, the tardigrade, could survive such extreme conditions.
Representative Image Source: Pexels I Photo by Pixabay
Researchers from the University of Oxford and Harvard University have dubbed the tardigrade “indestructible.”A 2017 study suggests these tiny aquatic animals have the best chance of surviving catastrophic astrophysical events.
The study examined potential world-ending events triggered by space elements, including supernovae, gamma-ray bursts, large asteroid impacts, and passing stars. The findings revealed that humans would not survive such catastrophes, as they would boil Earth’s oceans. However, tardigrades were found to be the only creatures likely to withstand these extreme conditions.
Image Source: A model tardigrade is seen in a display case at The Grant Museum on February 20, 2024, in London, England. (Photo by Leon Neal/Getty Images)
These tiny creatures, known as water bears or moss piglets, are invisible to the naked eye. With plump, segmented bodies and flattened heads, they are harmless to humans but incredibly resilient in extreme conditions.
Tardigrades have existed for at least 600 million years and have survived all five mass extinction events. They can enter a hibernation state called cryptobiosis, expelling over 95% of the water from their bodies. They can withstand temperatures from -460°F to 302°F, extreme pressure, and intense radiation.
Representative Image Source: Pexels I Photo by Marco Allasio
These plump yet tiny mammals were first discovered in 1773 by German zoologist J.A.E. Goeze who looked through a microscope at a sample of water and was surprised to discover a tiny, eight-legged, slow-moving animal. He decided to call it “Kleiner Wasserbär” which in German stands for “little water bear.” In 1776, Italian biologist Lazzaro Spallanzani came up with a name and called it a “tardigrada,” which in Italian means “slow stepper,” as per Smithsonian Magazine.
Meanwhile, the co-author of the study, Dr David Sloan, elaborated on the findings. He said in a statement, “To our surprise, we found that although nearby supernovae or large asteroid impacts would be catastrophic for people, tardigrades could be unaffected.” He added, “Therefore it seems that life, once it gets going, is hard to wipe out entirely. Huge numbers of species, or even entire genera may become extinct, but life as a whole will go on.”
The District of Columbia Water and Sewer Authority—now known as D.C. Water—has long provided water and sewer services to Washington, D.C. But for the past decade, the utility has also had an unexpected side hustle: turning human wastewater into fertilizer with flourishing results.
At most wastewater treatment plants, flushed water is cleaned, while the remaining solid matter is hauled away for disposal. Over time, transporting and disposing of that waste can cost millions of dollars while increasing carbon emissions from the trucks carrying it. A decade ago, however, D.C. Water decided to invest in transforming the solid waste into “humanure” rather than throwing it away.
Growin’ grass and makin’ gas
At the end of the wastewater treatment process, the collected human waste solids are processed into biosolid fertilizer using technology developed by Norwegian company Cambi. The process doesn’t just produce high-quality fertilizer—it also generates biogas that can be put to good use.
“So you get up to 40% more biogas,” Cambi CEO Eirik Fadnes said. “That biogas can be used to generate electricity to be used elsewhere in the wastewater-treatment plant or put on the grid and sold.”
D.C. Water sells the biosolid fertilizer under the brand name Bloom, and it’s already proving to be a success. Bloom has been used throughout the Washington, D.C., area by customers including Catholic University, Mount Olivet Cemetery, and the Franciscan Monastery. It’s also used on numerous lawns, school grounds, community gardens, and golf courses.
Success by the numbers
The numbers underscore D.C. Water’s success. To date, nearly 400,000 tons of Bloom have been sold across Washington, D.C., Maryland, Pennsylvania, and Virginia, generating $13.6 million in revenue. D.C. Water originally estimated it would take 20 years for Bloom to pay off its investment. But thanks to strong demand from institutions, landscapers, and local garden centers, the utility is now on pace to recoup that investment in just 12 years.
Bloom is also helping D.C. Water meet its environmental goals. By turning waste into a useful product instead of hauling it away for disposal, the utility has reduced its carbon footprint by roughly 50,000 metric tons of CO₂ emissions each year—the equivalent of taking more than 11,700 gas-powered cars off the road annually. The process also produces biogas, which can be converted into electricity to help offset the energy costs of wastewater treatment.
Human waste works wonders
None of this would matter if human biosolids weren’t effective at improving soil. “Humanure,” a term coined by Joseph Jenkins, refers to compost made from properly treated human waste. Because human feces can contain disease-causing pathogens, it must be handled carefully. After all, we call it “waste” for a reason.
When human waste is composted correctly, naturally occurring microbes break down the organic material while generating enough heat to destroy harmful pathogens. Over time, the result is a nutrient-rich compost that can improve soil health. Some farmers even build specialized outdoor composting toilets to create humanure for use on their land.
Should D.C. Water continue on this path of simultaneous profitability and environmental improvement, it’s likely other wastewater treatment plants will follow its lead.
According to NASA, wildfires have doubled worldwide due to climate change. Throughout the globe, governments and environmentalists have been trying to find ways to curb the fires. One particular national park in Spain has found a solution that has been keeping them fire-free for over a decade: donkeys.
Since 2014, the Firefighting Donkey Battalion unit consisting of 18 donkeys has been preventing wildfires in Doñana National Park in Doñana, Spain. The mission these donkeys do is simple: eat the dry brush that usually sparks and fuels wildfires. The donkeys spend up to seven hours a day using their voracious appetites to graze and clear a 130 by 50 feet area of dried grass, scrub, and other vegetation.
Why donkeys?
While humans can do this type of clearing out of dry brush, using donkeys for this work is arguably more effective. While it is a slower process, it is consistent and thorough. Donkeys are able to quietly patrol in areas that are inaccessible to vehicles. In exchange for the feasting, the donkeys get about eight gallons of water and rest. No money or fuel needed.
The donkeys’ bodies are also pretty much built for this kind of environmental work, too. Their stomachs are built to eat the same rough and dry grass repeatedly without issues. These daily grazings slowly but surely remove potential origin sources for fires. As a bonus, the donkeys are naturally disposing of the dried vegetation whereas humans would have to find a different way to dispose of it.
Having donkeys or other livestock graze in such areas was once more common in agriculture prior to modern farming. Some argue that the machinization of farming and urbanization have reduced the number of grazing animals. This in turn allows more vegetation growth that become dry spots for more wildfires to occur.
The method expands
This method has been so successful that other areas of Spain have adopted it. In 2020, Tivissa launched the Burros Bomberos project with three donkeys to so much success they’ve expanded. They now have 40 donkeys grazing and clearing nearly 400 hectares of land.
The Andrea Association in Allariz uses a team of donkeys to clear and maintain nearly 1,000 hectares of a biosphere reserve. Using GPS to monitor the donkeys’ activity, the group of grazers travel 19 kilometers per day to feed. Similar initiatives have since started in Basque Country, Catalonia, and Galicia, too.
In the United States, California has been using goats in a similar function. The group Fire Grazers Inc. has been contacted throughout California to bring hundreds of goats to eat dried vegetation. Much like donkeys, goats are built to eat rough and dry brush. This includes certain plants such as star thistle that are painful for human hands to grab.
It’s important to note that donkeys or other animals that eat dry scrub are the primary solution to wildfires. The same folks behind these initiatives also advocate proper forest planning and land management. This includes reducing the amount of easily flammable species of plants and trees such as pine. It takes thought, care, work, and maybe a bunch of donkeys to make a difference.
Wearebiologists who for many years have been trying to figure out what feral or outdoor-roaming pet cats eat outside.
When domesticated cats – Felis catus – live freely in the wild or are allowed to hunt outside the homes where their owners live, they are an invasive species, which live in every ecosystem of the world except the continent of Antarctica. We wanted to know all of the species they eat – and to what degree free-ranging cats are eating endangered or threatened species.
Examining reams of research
Over the past two decades, we have evaluated hundreds of scientific findings, including searching through Google Scholar and Web of Science using the keywords “cat predation,” “feral cat,” “cat diet” and “Felis catus.” For each item we found, whether peer-reviewed or not, we evaluated whether it contained conclusive evidence of cat diet or predation. We also reviewed each one’s reference section for additional unique articles or databases pertaining to cat diet and predation, and included those in our search.
Overall, we identified 533 unique publications – books, journal articles, theses and agency reports – that reported specific animal species consumed by cats. Cats’ plant-eating habits are occasionally, but haphazardly, noted in studies, so we did not include them in our analysis.
Our initial work focused on an overall assessment of what free-ranging cats eat around the world. Published in 2023, this paper analyzed the 533 studies on cat diet or predation events published over more than a century and found that cats ate nearly 2,100 different species of animals, including invertebrates.
Most of the species cats ate were vertebrates – mostly birds, followed by mammals and reptiles. But the data also indicated that at least 7% of the species cats eat are insects and other invertebrates, particularly beetles, and less frequently crustaceans, arachnids, centipedes, snails and slugs, and millipedes.
Many of the cat studies we reviewed did not report on how many individuals of a given species cats ate, so it was unclear what the total amount of insects was or how many calories cats are deriving from insects.
Invertebrates make up more than 70% of all terrestrial animal species and are important pollinators, predators and herbivores in virtually every nonmarine ecosystem. Many invertebrates are in decline globally due to urbanization, habitat destruction, increases in both light and pesticide pollution, and climate change. So we dug deeper into the data to understand what invertebrates cats are eating.
While a little more than one-third of all the studies we analyzed included invertebrates as part of cats’ diet, most of those failed to identify specific species of invertebrates. But we were able to find identifications of 148 invertebrate species.
Of those, two are considered endangered by the International Union for Conservation of Nature: the Aldabran grasshopper (Pternoscirtus aldabrae) in Seychelles and the Tasmanian giant freshwater crayfish (Astacopsis gouldi), which can grow up to 13 pounds (6 kilograms). Two others are considered vulnerable: wētāpunga (Deinacrida heteracantha), an insect native to New Zealand that can be about the size of a mouse, and the common yabby (Cherax destructor), a freshwater crayfish native to southeastern Australia. One other, the Canary Islands horned beetle (Arhopalus pinetorum), is listed as “near threatened.”
We have not found formal research evaluating how cats’ eating habits affect invertebrate populations. And for many species, they are likely not as significant a factor as wide-scale pesticide use.
But it’s possible that cats could be significant contributors to the deaths of rare species or in specific locations.
In many places, invertebrates provide an easy source of food. Whether in an urban backyard or on a remote island, cats are unlikely to turn a blind eye to available prey. And some cats may find it entertaining to chase, catch and eat insects even if they don’t need their nutrition.
A challenge of researching this question is that many invertebrates are relatively small, which makes direct observation in the field harder and can require more analytical approaches in the lab. And they have soft bodies, without distinguishing characteristics that could be easily recognized in scat or stomach contents.
However, molecular technologies can identify species using trace amounts of DNA left in the environment by animals. Promising new studies are beginning to identify what cats eat by analyzing the DNA found in their stomachs and scat. That research may help explore in even more detail what cats are eating in the outdoors, and how it’s affecting various species and the environment as a whole.
