Most spiders have eight legs, no ears and use fine leg hairs connected to nerve cells or their webs to hear sounds in their environment. But how do they smell?

A new study by an international team of researchers has found that male spiders “smell” with their legs, using olfactory hairs — wall-pore sensilla — as their “nose” to detect sex pheromones released by females.

“Spiders have always lived alongside humans, so it’s surprising how much we still don’t know about them. One long-standing mystery was related to how spiders detect smells. Now, our latest research has finally uncovered the secret,” Dan-Dan Zhang, one of the study’s authors and a sensory biology researcher at Lund University, wrote in The Conversation.

Other contributors include Gabriele Uhl, a professor of general and systematic zoology at the University of Greifswald, and Hong-Lei Wang, also a sensory biology researcher at Lund.

The discovery came after a decade of searching for the sensilla, which the research team identified and mapped.

The study, “Olfaction with legs — Spiders use wall-pore sensilla for pheromone detection,” was published in the journal Proceedings of the National Academy of Sciences.

Spiders have been evolving for approximately 400 million years and are known for their sense of vibration. Some species, like jumping spiders, also have excellent vision, but their sense of smell remained a mystery.

There was ample scientific evidence that spiders have the ability to detect odors like sex pheromones, but there were still two main questions. The first was, what is the primary olfactory organ spiders use to detect scent? The second was built upon previous studies suggesting that spiders did not have wall-pore sensilla, leading scientists to wonder how they were able to smell anything.

“Our study has solved these long-standing questions. We discovered previously overlooked wall-pore sensilla on the walking legs of male wasp spiders (Argiope bruennichi) and demonstrated that they can use them to detect airborne sex pheromones with high sensitivity,” Zhang wrote in The Conversation. “We showed that the wall-pore sensilla are not unique to wasp spiders but are prevalent across the spider tree of life.”

The team looked at female and male A. bruennichi spiders using high-resolution electron microscopy. They found that all male spiders’ walking legs had thousands of wall-pore sensilla and discovered specific features of the sensilla. They determined that they are distinct from those of insects and other arthropods.

The sensilla are found on the upper region of the legs of male spiders, close to the body, in areas that rarely come into contact with the surface as spiders walk, mate or capture prey.

“This distribution pattern already suggested the role of wall-pore sensilla in detecting airborne odours (olfaction). Interestingly, wall-pore sensilla were found exclusively in adult male spiders, not in juvenile males or females, which strongly indicates their function in mate searching and recognition,” Zhang and colleagues wrote in The Conversation. “A. bruennichi is one of the few spider species in which the chemical structure of the sex pheromone has actually been identified. Female spiders release gaseous pheromones that attract males from a distance.”

The researchers tested whether a pheromone compound would trigger a response in the wall-pore sensilla. They used a microscope to observe live male spiders, placing a recording electrode into one of their wall-pore sensilla.

“We then exposed each sensillum to a puff containing the pheromone compound. We found that even a tiny amount of the pheromone compound — just 20 nanograms — was sufficient to elicit a clear response as a burst of activity in neuronal cells from a wall-pore sensillum, and the response became stronger as the dose increased. We consistently observed the response of wall-pore sensilla to the pheromone compound, regardless of which leg pair was tested,” the researchers wrote.

Contact and non-contact areas on body appendages of a male A. bruennichi. Slow-motion footage (500 frame per second) of a male walking on a horizontal skewer. The video highlights that only the distal leg segments make contact with the surface. PNAS

The results demonstrated that the olfactory sensilla of spiders are extremely sensitive in comparison with insects’ most responsive sex pheromone communication systems. Spiders have thousands of sensilla on each of their walking legs, enabling males to pick up even faint traces of airborne sex pheromones.

To get a better sense of the broader world of wall-pore sensilla, the research team looked at 19 other species of spiders across 16 families. They found that, in most species, males have wall-pore sensilla.

They also discovered that “basally branching spider groups” like basal trapdoor spiders in Asia did not have sensilla. The pattern the researchers uncovered suggested sensilla have evolved independently within spiders multiple times, but had been lost in some lineages.

“Our study paves the way for exciting future discoveries about how spiders perceive the world through olfaction. Many intriguing questions await further investigation,” the trio of scientists wrote in The Conversation. “How do female spiders smell without wall-pore sensilla? And beyond sex pheromones, what other chemicals can spiders detect and how are these relevant to their behaviour and ecology? Also, what is the molecular and neural basis of spiders’ olfaction? Finally, how has the sense of smell evolved across the vast diversity of spider species?”

“These questions set the stage for an exciting new chapter in our understanding of spider biology,” they said.

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Fueled by the climate crisis, the global average temperature soared above the 1.5 degrees Celsius threshold for the first time in 2024, intensifying extreme weather.

Experts from the United Nations World Meteorological Organization (WMO) have confirmed that last year was the planet’s hottest on record, reaching 1.55 degrees Celsius above the pre-industrial average, reported UN News.

“We saw extraordinary land, sea surface temperatures, extraordinary ocean heat accompanied by very extreme weather affecting many countries around the world, destroying lives, livelihoods, hopes and dreams,” said Clare Nullis, WMO spokesperson, as UN News reported. “We saw many climate change impacts retreating sea ice glaciers. It was an extraordinary year.”

Four out of six of the international datasets analyzed by WMO showed a global average temperature for 2024 that was higher than 1.5 degrees Celsius, while two did not.

The 1.5 degrees Celsius average is the goal temperature threshold of the 2015 Paris Agreement, with an overall target of temperatures worldwide remaining “well below” two degrees Celsius above the pre-industrial average.

WMO maintained that the Paris Agreement was “not yet dead but in grave danger,” explaining that the long-term temperature goals of the accord were measured across decades, not individual years.

WMO Secretary-General Celeste Saulo emphasized that “climate history is playing out before our eyes. We’ve had not just one or two record-breaking years, but a full ten-year series.”

“It is essential to recognize that every fraction of a degree of warming matters. Whether it is at a level below or above 1.5C of warming, every additional increment of global warming increases the impacts on our lives, economies and our planet,” Saulo said.

WMO weather experts said the catastrophic and deadly Los Angeles wildfires were made worse by climate change, with rains boosting vegetation growth, followed by more days of warm, dry and windy weather.

Data from the European Union’s Copernicus CIimate Change Service (C3S) showed that the amount of our planet affected by a minimum of “strong heat stress” reached a new annual maximum on July 10, 2024, when a record approximately 44 percent of Earth was impacted by “strong” to “extreme heat stress.” That’s five percent more than the average yearly maximum.

“There’s now an extremely high likelihood that we will overshoot the long-term average of 1.5C in the Paris agreement limit,” said Dr. Samantha Burgess, deputy director of C3S, as reported by The Guardian. “These high global temperatures, coupled with record global atmospheric water vapour levels in 2024, meant unprecedented heatwaves and heavy rainfall events, causing misery for millions of people.”

Last year, the average human was exposed to an extra six weeks of dangerous heat, which intensified heat waves across the globe.

UN Secretary-General António Guterres said the findings by WMO are more proof of global heating, and urged governments to deliver updated national climate action plans in 2025 to limit the long-term temperature rise to 1.5 degrees Celsius, UN News reported.

“Individual years pushing past the 1.5℃ limit do not mean the long-term goal is shot,” Guterres said. “It means we need to fight even harder to get on track. Blazing temperatures in 2024 require trail-blazing climate action in 2025.”

“There’s still time to avoid the worst of climate catastrophe. But leaders must act – now,” Guterres added.

Datasets used by WMO in their analysis were taken from NASA, the United States National Oceanic and Atmospheric Administration, the European Center for Medium Range Weather Forecasts, the UK Met Office working in collaboration with University of East Anglia’s Climatic Research Unit, the Japan Meteorological Agency and Berkeley Earth.

WMO also highlighted a separate study on ocean warming, saying it had played a major role in the record high temperatures in 2024.

“The ocean is the warmest it has ever been as recorded by humans, not only at the surface but also for the upper 2,000 metres,” WMO said, citing the findings, which spanned seven countries and were published in the journal Advances in Atmospheric Sciences.

WMO noted that the ocean stores roughly 90 percent of excess heat produced by global warming, “making ocean heat content a critical indicator of climate change.”

WMO explained that the upper part of the ocean became warmer by about 140 times the planet’s total electricity output from 2023 to 2024.

“This record needs to be a reality check. A year of extreme weather showed just how dangerous life is at 1.5C. The Valencia floods, U.S. hurricanes, the Philippines typhoons and Amazon drought are just four disasters last year that were worsened by climate change. There are many, many more,” said Dr. Friederike Otto, a climate science senior lecturer at Imperial College London’s Grantham Institute for Climate Change, as reported by The Guardian. “The world doesn’t need to come up with a magical solution to stop things from getting worse in 2025. We know exactly what we need to do to transition away from fossil fuels, halt deforestation and make societies more resilient.”

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A quarter of all freshwater animals, including crustaceans, fish and insects, face a high risk of extinction from threats like pollution, farming and dams, a new study has found.

Rivers, lakes, wetlands and other bodies of freshwater cover a relatively small amount of Earth’s surface — less than one percent — but are home to more than 10 percent of the planet’s known species, including a third of vertebrates and half of fish, reported AFP.

“Freshwater ecosystems are highly biodiverse and important for livelihoods and economic development, but are under substantial stress. To date, comprehensive global assessments of extinction risk have not included any speciose groups primarily living in freshwaters,” the authors of the study wrote. “Here we present the results of a multi-taxon global freshwater fauna assessment for The IUCN Red List of Threatened Species covering 23,496 decapod crustaceans, fishes and odonates, finding that one-quarter are threatened with extinction. Prevalent threats include pollution, dams and water extraction, agriculture and invasive species, with overharvesting also driving extinctions.”

Roughly 30 percent of decapods — like crabs, shrimp and crayfish — were found to be at risk, compared with 16 percent of odonates such as dragonflies, 23 percent of tetrapods like reptiles and frogs and 26 percent of fish, AFP reported.

Since the year 1500, 89 freshwater species are known to have become extinct, with an additional 178 suspected to have ceased to exist. The study’s authors said the figures are likely underestimated since there is so little information about certain species.

“Most species don’t have just one threat putting them at risk of extinction, but many threats acting together,” said Catherine Sayer, an International Union for Conservation of Nature zoologist who was co-author of the study, as reported by The Associated Press.

The study said that, between 1970 and 2015, 35 percent of wetland area had been lost.

There “is urgency to act quickly to address threats to prevent further species declines and losses,” the authors wrote in the study.

According to the findings, approximately a third of rivers more than 620 miles long are no longer free-flowing throughout their full length.

“Until recently, the freshwater realm has not been given the same priority as the terrestrial and marine realms in global environmental governance,” the authors wrote.

Stuart Pimm, a Duke University ecologist who did not contribute to the study, called the findings “hugely important,” The Associated Press reported.

“Almost every big river in North America and Europe is massively modified” by dams, which put freshwater species at risk, Pimm said.

South America’s Amazon River ecosystem is under threat from deforestation, illegal gold mining and wildfires, Charvet said. Forest clearing through illegal burning produces ash that ends up in the river, while mercury gets dumped into the water by unlicensed goldminers, Charvet explained.

Wetlands and rivers “concentrate everything that happens around them,” Charvet added. “If something goes really wrong, like an acid or oil spill, you can threaten an entire species. There’s nowhere else for these animals to go.”

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Wildfires fueled by strong winds in Pacific Palisades and Altadena, California, have scorched a quickly growing area of Los Angeles County, killing at least two people.

The fierce and unpredictable fires have forced roughly 70,000 evacuations and destroyed approximately 1,000 buildings and homes, reported the Los Angeles Times.

“We woke up to a dark cloud over all of Los Angeles, but it is darkest for those who are most intimately impacted by these fires,” said Los Angeles County Supervisor Lindsey Horvath, as the Los Angeles Times reported. “It is difficult to process the immensity of the destruction and loss, and we extend our hearts and every resource we have to all of our impacted residents.”

The Palisades fire has burned over 5,000 acres all the way to the Pacific Coast Highway, destroying many homes, said LA County Fire Chief Anthony Marrone during a Wednesday morning news conference.

“Extreme fire behavior, including short and long-range spotting, continues to challenge firefighting efforts for the Palisades fire. Winds gusts up to 60 MPH are expected to continue through Thursday, potentially aiding in further fire activity and suppression efforts,” according to the California Department of Forestry and Fire Protection (Cal Fire).

The Eaton fire has charred over 2,200 acres near Pasadena and Altadena, fanned by wind gusts as high as 99 miles per hour, reported the Los Angeles Times. The fire has claimed two lives and caused serious injuries, with over 100 structures destroyed, Marrone said.

A third fire, the Hurst fire, spread rapidly overnight when high winds whipped up in Sylmar, burning more than 500 acres.

Red flag warnings were in effect for both LA County and large areas of Ventura County until at least Thursday, as officials warned of a “life threatening, destructive and widespread windstorm.”

Weather forecasters predicted winds would ease during the day on Wednesday, but remain through Friday.

In the San Gabriel Mountains, Hollywood and Beverly Hills and coastal areas alongside the Santa Monica Mountains, Sepulveda Pass, eastern Venturn Valley and Malibu, the National Weather Service warned of a “particularly dangerous situation.” 

A red flag warning of this nature is expected to be issued by the National Weather Service an average of about once in three to five years, rather than the three times it has this fire season alone.

“We are absolutely not out of danger yet,” said Los Angeles Fire Department Chief Kristin Crowley, adding that “these fires are stretching the capacity of emergency services to the maximum limits.”

LA County Sheriff Robert Luna said evacuation orders had been given to 32,500 residents in areas affected by the Eaton fire, with an additional 37,000 evacuated due to the Palisades fire.

“When we looked out the window there was this giant orange glow, so we went outside to see what it was and when looked to the left we saw this smoke plume coming from the Pacific Palisades,” said Marika Erdely, resident of the Topanga neighborhood in Pacific Palisades, as reported by CNN. “When I got the evacuation notice my cousin and I quickly put our things into bags and laundry baskets and left. The northbound lane was completely full, and first responders were trying to get through. Just the sounds and everything were very scary. It felt apocalyptic.”

Lack of winter rains has extended the Southern California fire season, the Los Angeles Times reported. Downtown Los Angeles has received just 0.16 inches of rain since the start of the water year on October 1 — a fraction of the average 4.64 inches it normally gets.

“Southern California has experienced a particularly hot summer, followed by almost no precipitation during what is normally our wet season,” said Alex Hall, UCLA Center for Climate Science director, as reported by the Los Angeles Times. “And all of this comes on the heels of two very rainy years, which means there is plenty of fuel for potential wildfires.”

Jim McDonnell, chief of the LA Police Department, advised residents to stay vigilant, whether they’re currently in an evacuation area or not.

“These are unprecedented conditions, but also unpredictable,” McDonnell said. “As the fires continue to spread and pop up in different locations, none of us know where the next one is going to be.”

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Following years of campaigning by environmental activists, Thailand has banned foreign imports of plastic waste due to concerns about toxic pollution.

Experts warn that the failure to reach an agreement on a global treaty to eliminate plastic waste will have adverse impacts on human health, reported The Guardian.

“The ban on imports will help stimulate plastic recycling in Thailand, ensuring more efficient resource usage and reducing the amount of unused plastic waste,” said Arada Fuangthong, director-general of Thailand’s Department of Foreign Trade, as Sustainable Plastics reported. “This will also help reduce pollution that could impact the environment and public health.”

Fuangthong added that Thailand’s plastic waste problem has increased “significantly,” and that the country has struggled with electronic waste being smuggled in mixed with plastic waste.

Issued by the Thai Department of Foreign Trade on January 1, the new regulation provided a grace period from December 17 to 31 to allow for the completion of pending imports.

The guidelines require the promotion of domestic plastic waste recycling by responsible agencies under the Bio, Circular, Green (BCG) economy model framework.

Thailand became a main destination for plastic waste exports from the United States, Japan, Europe and the United Kingdom after a ban was imposed by China — the largest household waste market in the world — in 2018, reported The Guardian.

Japan is among the biggest waste plastic exporters to Thailand, sending roughly 50 million kilograms of discarded plastics in 2023.

According to Thai customs officials, over 1.21 million tons of plastic scraps were received by the country from 2018 to 2021.

“The ban on all plastic scrap imports should be seen as a triumph for civil society in preventing hazardous waste from entering Thailand,” said Penchom Sae-Tang, director of NGO Ecological Alert and Recovery, as the Bangkok Post reported. “However, our work is far from over. Vigilant monitoring and robust cooperation with authorities will be critical to ensuring the law is enforced for the benefit of all.”

Plastic waste imports have been frequently burned by factories rather than being recycled, leading to negative impacts for the environment and human health, reported The Guardian.

“While this is a great step forward for Thailand, there is more work to be done. After the law comes into effect, the Thai government must work to ensure its enforcement and implementation. This means industrial, environmental and customs agencies must cooperate to prevent any illicit imports of plastic waste… the current law does not address the transit of plastic waste, meaning Thailand could be used as a transit state to send waste to our… neighbours. The Thai government must guard against this,” said Punyathorn Jeungsmarn, a plastics campaign researcher with the Environmental Justice Foundation, as The Guardian reported.

European exports of plastic waste to non-OECD nations have increased over the past several years, reported Sustainable Plastics.

Rules regulating the global export of plastic scrap exist, but compliance is hard to assess.

Thailand’s new ban comes as attempts to rescue the global plastics treaty continue. Countries failed last year to agree on a final draft following talks in Busan, South Korea.

A draft text was supported by more than 100 countries, but oil-producing nations like Saudi Arabia, Russia and Iran resisted cuts to plastics production.

A date has not yet been set for further discussions on a global treaty to eliminate plastic waste.

“Plastic pollution is now recognised as not only an environmental crisis but also a critical human health crisis. The need for decisive international action to tackle plastic pollution has never been more urgent,” said professor Steve Fletcher, director of University of Portsmouth’s Revolution Plastics Institute, as The Guardian reported.

Fletcher pointed out that burning plastic as a waste management method posed severe health risks that were compounded by the plastic waste trade.

“With 16% of global municipal waste burned openly, rising to 40-65% in low-and middle-income countries, vulnerable populations bear the brunt of this crisis. The toxic fumes from burning plastic are a silent but deadly contributor to global health burdens. Urgent action is needed,” said Dr. Cressida Bowyer, deputy director of Revolution Plastics Institute, as reported by The Guardian.

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