Curious Kids: can spiders swim?

Leanda Denise Mason, Edith Cowan University

Can spiders swim?

Waubra Preschool students, Victoria, Australia

What a great question!

Most spiders don’t swim by choice. But they sure can survive in water when they need to. From floating like a boat, to paddling like a rower, to carrying their own scuba bubbles, spiders have developed brilliant ways to deal with water.

Let’s dive into the science in some more detail, and look at how spiders handle getting their paws wet, with examples from our local bush.

Spiders can run across water

Water has surface tension – this acts like a kind of invisible skin that can hold up small, light objects.

Many spiders are tiny and have water-repellent hairs on their legs, so they can stand or run on water without sinking.

For example, fishing spiders wait at the water’s edge and scuttle across the surface to grab insects, tadpoles or even small fish.

If prey escapes underwater, this spider can even hide beneath the water’s surface briefly, then come back up.

Spiders can hold their breath underwater for days

Spiders don’t have gills, so they can’t get oxygen from water like fish do. But they have evolved clever strategies for staying alive if they stay in the water for a long time.

For example, the Australian Sydney funnel-web spider often falls into backyard swimming pools. People might see one and think it drowned, but it can actually survive underwater for hours by holding its breath much longer than a human could.

That’s because it breathes much more slowly than we do. Like many spiders, it has both tracheae (tiny air tubes) and book lungs (they look like a book with many pages) for breathing. Some spiders can close these and become watertight, to hold their breath for a long time.

Some trapdoor spiders have been recorded only taking a breath every six minutes.

Do not burst their bubble

Some spiders take the air with them like a scuba diver.

On the Great Barrier Reef coast, a little intertidal spider called Desis bobmarleyi actually lives part of its life under seawater. At high tide, it hides in a silk-lined air pocket in coral or shells. It uses the long hairs on its legs and body to trap a bubble around itself so it can breathe underwater between the tides. When the tide goes out, this spider comes out to hunt on the wet reef.

And in other parts of the world, there’s the famous diving bell spider, the only spider that spends its whole life entirely underwater.

It weaves an underwater silk web that it fills with air – like an underwater house. This spider can stay underwater for more than a day at a time by letting its air-bubble vessel actively pull oxygen from the water.

Can you spot Desis bobmarleyi among the corals? coenobita/iNaturalist, CC BY

Flood proofing, trapdoor spider style

Some spiders sit tight and make their homes flood-proof. Remember those trapdoor spiders we mentioned? Trapdoor spiders live snug in burrows underground with a silken lid on top (like a little trapdoor).

In areas that get sudden heavy rains, a trapdoor spider might build its burrow with a raised entrance – a bit like a chimney – so water flows around or over it rather than straight in.

Some Australian trapdoor spiders in the outback clay pans have been found to build thick muddy silk doors that fit perfectly like a bath plug into the surrounding soil. The water just goes straight over the top.

Even if water does get in, some trapdoor spiders can seal their bodies and essentially hold their breath. They don’t swim in their flooded burrows, but they can wait out a flood without drowning.

What to do with a soggy spider

If you ever find a spider struggling in water – say in a swimming pool or even in a bucket – you can help as long as you’re careful.

First, always ask an adult before trying to assist a spider. Nobody has died in Australia in 60 years from spider venom. But some (such as the Sydney funnel-web) can still be fatal, so you must be sure not to touch or provoke it.

A good way to save a spider in a pool is to use a net or a scoop with a long handle. Gently lift the spider out and put it on the ground away from the water. The spider might look dead at first, but don’t be surprised if it “comes back to life” as it dries out – just like trapdoor spiders do.

And remember: never poke a spider with your bare hands, even if it seems lifeless. Spiders such as funnel-webs can still bite underwater or right after being rescued, and they will defend themselves if they feel threatened. So, play it safe and use tools or ask an adult or a spider expert to help.

If anyone is bitten, get an adult to seek medical attention immediately.

Next time you’re exploring nature (or even looking into the toilet), keep an eye out for our eight-legged friends and how they interact with water. You might spot a little spider boat captain or an air-bubble diver right in your backyard.

Leanda Denise Mason, Vice Chancellor Research Fellow in Conservation Ecology, Edith Cowan University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→July 17, 2026

What happens inside a tennis player’s brain as they try to return a 148mph serve?

OpenStax College/Anatomy & Physiology, Connexions website via Wikimedia., CC BY-NC-SA

Michelle Spear, University of Bristol

The fastest serve so far at this year’s Wimbledon tennis championships was struck by the Argentinian Thiago Agustín Tirante on the opening day.

His serve of almost 148mph (238km/h) was still some way under the Wimbledon record of 153mph, set by Frenchman Giovanni Mpetshi Perricard in 2025. And despite Tirante giving his opponent less than a fifth of a second to play each serve, he lost the match in straight sets.

Which means his rocket serves were successfully returned on lots of points. Our emerging understanding of how the human brain works can help explain how this feat is achieved.

Whether you’re a player or a spectator, the ability to see a tennis ball travelling that quickly across the court is a marvel of human physiology. At nearly 150mph, the ball is travelling faster than anyone can watch it move.

By the time your brain has processed the sight of the ball leaving the racket, it is already well on its way to the other end of the court. Yet professional tennis players return these high-powered serves with astonishing accuracy.

The reason is that they do not rely on reaction alone. Returning a tennis serve depends on one of the brain’s most remarkable abilities: predicting the future.

Predicting the future

Tennis players – and spectators – face the same basic problem: the visual information arrives in their brain slightly late.

Before a player becomes aware of a tennis ball hurtling across the court, light reflected from its surface has to be detected by their eyes’ retinas, converted into electrical signals, then transmitted along the optic nerves to the brain. There, the visual cortex begins analysing its colour, shape, speed and direction.

Even under ideal conditions, this takes around a tenth of a second. During that time, a ball travelling at nearly 148mph will have covered several metres.

For a spectator, this delay is rarely noticeable. The brain’s predictions are so accurate that the ball appears to move smoothly across the court, despite what you are seeing being a fraction of a second out of date.

But the player standing at the other end of the court needs to do a lot more than just watch the ball. They must move their body to that specific point on the court, position their racket and time their swing with great precision if they want to be in with a chance of winning the point.

In fact, much of this process begins before the ball has even left the opponent’s racket. It is an extraordinarily complex system.

How the brain works it all out

As the server prepares to strike the tennis ball, the receiver is already gathering information. The height and position of the ball toss, the rotation of the server’s trunk, the movement of their shoulder and forearm, the angle of the racket face and the speed of the swing all provide clues about what is about to happen.

Elite players have, of course, spent many thousands of hours learning to recognise these subtle biomechanical cues. Their brains combine the latest cues with all that previous experience to estimate the likely speed, direction and spin of the serve – before the ball has even crossed the net.

Central to this is the cerebellum, a densely folded structure tucked beneath the back of the brain. Although best known for coordinating movement and balance, advances in brain imaging and computational neuroscience have revealed it is also one of the brain’s great prediction engines.

Rather than simply responding to sensory information as it arrives, the cerebellum continuously generates internal models of how the body and external world behave. As fresh visual information reaches the brain, these models are updated almost instantaneously, allowing movements to be adjusted before conscious awareness has caught up.

But the cerebellum does not work alone. A specialised region of the visual cortex, known as area MT or V5, is exquisitely sensitive to movement, and calculates the speed and direction of the ball as it crosses the player’s visual field.

This information travels along the dorsal visual stream – often called the brain’s “where pathway” – to the posterior parietal cortex, where the ball’s position is integrated with information about the player’s own body.

The brain’s two visual streams

OpenStax College/Anatomy & Physiology, Connexions website via Wikimedia., CC BY-NC-SA

From there, premotor regions begin preparing possible movements. The supplementary motor area helps organise their sequence, and the primary motor cortex sends commands to the muscles of the trunk, shoulder, arm and wrist.

At the same time, the frontal eye fields and the superior colliculus (a small structure in the midbrain that rapidly redirects the eyes towards objects of interest) generate rapid eye movements towards where the ball is expected to be next – rather than where it was a fraction of a second ago.

This is why the fastest returns in tennis are not simply feats of lightning-fast reflexes. They are the product of a brain that is constantly making, testing and refining predictions. The players who appear to have more time have become exceptionally good at anticipating what will happen next.

Tennis and beyond

Neuroscientists are still trying to understand why some tennis players acquire these remarkable predictive skills faster than others. Is it simply a matter of hours spent on court, or are some brains naturally better equipped to build the internal models that underpin elite performance?

For now, the answer appears to be a combination of both.

Understanding how the brain predicts movement has implications far beyond tennis. Similar neural mechanisms help us catch a falling glass before it hits the floor, judge when it is safe to cross a busy road, or drive through traffic.

These predictive systems are becoming an important focus of neuroscience research. Insights into how the cerebellum and wider motor networks anticipate movement are helping researchers improve rehabilitation after neurological injury, understand disorders of movement and coordination, and design robots capable of interacting more naturally with an unpredictable world.

Meanwhile, insights from neuroscience might also help hone a future Wimbledon tennis champion.

Michelle Spear, Professor of Anatomy, University of Bristol

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→July 09, 2026

Want to be a citizen scientist? Here are 5 ways to get involved

Elodie Camprasse, CC BY-ND 

Miki Perkins, The Conversation

Ever wondered what it might feel like to spot giant spider crabs while you’re snorkelling? Or check plants for the circular holes that indicate native bees are collecting nest materials?

Citizen science relies on people like you – more than a million of them in Australia, actually – to collect and analyse valuable data about the world around us.

Here, we introduce five citizen science projects you can take part in. For most of them, all you need to get started is an app on your phone.

Science lives far beyond the lab, and it’s not just done by scientists.

In this series, we spotlight the world of citizen science – its benefits, discoveries and how you can participate.

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Spider Crab Watch

Elodie Camprasse, Honorary Fellow – School of Life and Environmental Sciences – Deakin University

Every winter in Port Phillip Bay in Naarm/Melbourne, tens of thousands of great spider crabs gather in shallow water to moult – shedding their shells and growing new ones that grow to about 16 centimetres. But scientists know surprisingly little about them. The gatherings can be unpredictable and short-lived, making them difficult for scientists to monitor alone.

Spider Crab Watch helps researchers fill these knowledge gaps. By bringing together observations from the public – including divers, snorkellers and fishers – scientists can better understand when and where gatherings occur, how long they last, and what environmental conditions might trigger them.

Citizen scientists have already logged hundreds of observations, helping researchers identify new gathering sites and better understand when aggregations occur. Participants can log when and where they see spider crabs – whether a single crab or a large group, in Port Phillip Bay or elsewhere. Photos are helpful but not essential. Empty shells washed up on beaches can also be logged.

Gatherings of great spider crabs can be fleeting and in different locations. Elodie Camprasse, CC BY-ND

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NOBURN

Sam Van Holsbeeck, Research Fellow – Forest Research Institute – University of the Sunshine Coast

NOBURN (the National Bushfire Resilience Network) is a citizen science project aimed at improving our understanding of the role of vegetation in bushfire risk. Using an app, people around Australia can log their observations – including site photographs – to support research into fuel dynamics, fuel load and bushfire risk.

Guided by the app, participants assess vegetation at a site, noting factors such as shrub density and overall fuel hazard. Observations typically take 10–15 minutes and can be conducted by community members, landholders, students or land managers. To date, we have collected 154 verified site observations and more than 160 registered users.

Observations supplied by citizen scientists help researchers understand the structure, density and dryness of forest fuels. Combined with AI, this data allows for better prediction of the likelihood and severity of fires. While this data is not as detailed as a full expert assessment, they provide useful indicative information, particularly in areas where formal fuel monitoring is limited.

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FrogID

Jodi Rowley, Curator – Amphibian & Reptile Conservation Biology – Australian Museum – UNSW Sydney

Australia’s frogs are in trouble. At least four species have been lost and dozens more are on the edge of extinction. Yet we lack the information needed to make informed decisions about how to conserve them. Frogs are very sensitive to environmental change. This makes them great indicators of environmental change (they’re often referred to as the “canary in the coal mine”). By monitoring them, we also gain insight into environmental health.

FrogID taps the keen eyes and ears of people across Australia to gather the data needed to help save Australia’s frogs.

Using our free app, people can record frogs wherever they hear them. The best time is after rain and in the first few hours after dark. Once submitted, Australian Museum frog experts listen to the recordings and identify species.

There are more than 100,000 registered users of FrogID who have together gathered almost 1.5 million records of frogs from across Australia. It’s safe to say this dataset has revolutionised our understanding of frogs in Australia – including finding 13 frog species new to science.

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1 Million Turtles

James Van Dyke, Associate Professor in Biomedical Sciences – La Trobe University

Freshwater turtle numbers have fallen 60–90% across most of the rivers and wetlands of Australia, amid engineered flows and increasingly dry conditions. As turtles disappear, they leave a large gap. Turtles are the “vacuum cleaners” of the waterways, eating decaying organisms and vegetation and improving water quality.

The 1 Million Turtles project aims to increase survival rates of freshwater turtles and turtle nests, and increase Australia’s turtle population by at least one million animals.

People of all ages can download and record any turtles or turtle nests they see in Australia. They can also volunteer for other activities, such as nest protection, via our website.

To date, our citizen scientists have logged nearly 34,000 turtle records across the country. They have also saved more than 2,600 turtles from dangerous road crossings, and protected more than 1,940 turtle nests from invasive foxes and pigs.

Assuming each nest held an average of 15 eggs, and half of the turtles saved on roads were adult females of reproductive age, our program has given 400,000 turtles the chance of a future in just the past five years.

Data from this community conservation program has led to the conservation status of turtle species being upgraded to threatened or endangered. It has also prompted the development of state conservation programs for turtles in New South Wales, Victoria and South Australia.

A broadshell turtle. Turtles are the ‘vacuum cleaners’ of the waterways, eating decaying organisms and vegetation and improving water quality. James Van Dyke, CC BY-ND

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Australian ‘leafcutter’ bees

Kit Prendergast, Research Fellow – School of Science – University of Southern Queensland

Native bee numbers are declining and we have limited information about them. There are more than 2,000 species of native bee, including the Megachile bee. Some species of Megachile bee use plant leaves or even petals to build their nests, giving them the common name of leafcutter bees.

We don’t yet know which plants these bee species rely on. This citizen science project allows the public to use an app to identify which plants the bees are relying on. By noting preferred plants, we’ll have a better idea of how to create habitats for these gorgeous native bees and pollinators.

Most native bees cannot be identified by citizens, due to the specialised skills required, and most diagnostic features being microscopic. But when it comes to plants, these are much better known among the public and can be identified easily by photos.

Members of the public can download the free iNaturalist app and when they see a plant that has distinctive discs cut out, or see a Megachile bee in action, they can take a photo of the leaf “damage”. Once completed, gardeners, land managers and farmers will be able to access an evidence-based list of which nesting plants should accompany food plants.

A megachile native bee cutting a leaf. Lynda Wilson, CC BY-ND

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Miki Perkins, Environment & Energy Editor, The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→June 19, 2026

Curious Kids: if our eyes see upside down, how does the brain flip the picture?

Daniel Joyce, University of Southern Queensland

I heard that we see upside down, but our brain flips the image. How does it do that?

–Jasmine, Mount Evelyn, Victoria

Our eyes work thanks to light. Objects we can see are either sources of light themselves – like a candle or a phone screen – or light bounces off them and makes its way to our eyes.

First, light passes through the optical components of the eyes such as the cornea, pupil and lens.

Together, they help focus the light onto the retina that senses light, while also controlling the intensity of light to help us see well while avoiding damage to the eye.

The function of the lens is to correctly focus light that comes from objects at different distances. This process is known as accommodation.

While performing this important task, light passing through the lens becomes inverted. This means that light from the top of the object falls lower on the retina than light from the bottom, which falls higher on the retina.

So, light exiting the lens to land on the retina is indeed flipped upside down. But that doesn’t mean the brain is actually flipping the picture “back”. Here’s why.

The orientation doesn’t actually matter

While the light being interpreted by the brain is “upside down” compared to the real world, the question is: is that actually a problem for us?

From your own experience you can tell the answer is probably no. We seem to navigate and interact with the world just fine.

So, where in the brain is the image flipped or rotated 180 degrees to be the “right way up” again?

You may be surprised to learn that vision scientists reject the idea a flipping or rotation needs to happen at all. This is because of how our brains process visual information.

The object you perceive is “encoded” by the firing of various neurons – brain cells that process information – in various locations in the brain. This pattern of firing is what encodes the information about the object you’re focusing on. That info takes into account the object’s relation to everything else in the scene, your body in the world, and your movements.

As long as the relative encodings of these are all consistent with one another, as well as stable, there’s no need for a flip to happen at all.

We can function with ‘upside down’ goggles!

Several studies have looked at how we adapt to large changes in visual input by asking people to wear goggles that flip the image coming in.

This means the image lands on the retina the “right way up”, so to speak, but upside down from what the brain has learned it should be.

In the 1930s, two scientists in Austria performed the Innsbruck Goggle Experiments. For weeks or even months at a time, participants in these studies wore goggles that altered the way the world around them looked. This included goggles that turn the incoming image upside down.

 

A person blinks while wearing an ‘invertoscope’ – goggles that turn the incoming image upside down. Dmitry Hoh/Wikimedia Commons, CC BY-SA

As you can imagine, people wearing these goggles at first found it really difficult to get by in their day-to-day activities. They would stumble and bump into things.

But this was temporary.

Participants reported seeing the world upside-down for the first few days, with difficulties navigating the environment, including trying to step over ceiling lights that appeared to them as on the floor.

Around the fifth day, however, performance seemed to improve. Things that were at first seen upside down now appeared the right way up, and this tended to improve with more time.

In other words, with continued exposure to the upside-down world, the brain adapted to the changed input.

More recent studies are beginning to identify which areas of the brain are involved in being able to adapt to changes in visual input, and what the limits of our ability to adapt might be.

Adaptation may even allow “colour blind” people to see colour better than is predicted from their condition.

Daniel Joyce, Senior Lecturer in Psychology, University of Southern Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→May 12, 2026

Couples share 30% of their gut bacteria. Here’s how that may affect health

Conor Meehan, Nottingham Trent University and Janelle Mwerinde, Nottingham Trent University

When living with a partner, you might be sharing more than just the same home, lifestyle and interests. You might also share various microscopic organisms residing on and in you.

This community of microorganisms, which consists of mainly bacteria, viruses and fungi, is known collectively as the human microbiome. The various microbiomes found throughout the body all play an important role in health.

From birth, the human microbiome is shaped by our interactions with our mother, who introduces diverse microorganisms that build our immune and digestive systems. As we get older, social interactions with our close community continue influencing this delicate ecosystem.

The people we live with have huge influence on what microbes we have in our microbiome. In fact, it’s thought that partners share around 30% of their resident microbes in the gut alone.

But it isn’t just the microbes in your gut that may be similar to your partner. The microbes in many other parts of the body may also be shared with your loved one – and this could potentially affect your health.

Gut microbiome

Diet and lifestyle are thought to have the greatest influence on the gut microbiome’s make-up. But studies on couples have found that living with your partner can also influence the microbiome.

Couples living together may share 13% to 30% of their gut bacteria. This was true even when diet (which many couples share) was factored out. Research also shows that couples who live together have greater microbial diversity compared to people who live alone.

This is good news for couples who co-habitate, as a more diverse gut microbiome is correlated with lower risk of irritable bowel syndrome, cardiovascular diseases and potentially high blood sugar.

But it might not all be good news. Research shows that some of the bacterial species couples share can have varying effects on health.

Take the bacteria from the Ruminococcus family. While some species of Ruminoccocus benefit health, others have been linked to negative health outcomes, including diabetes and irritable bowel syndrome.

So these bacteria may not always offer the same benefits in different demographics. This highlights the complexity of resident gut bacteria and their health impacts.

Oral microbiome

Sharing an oral microbiome with our partners might seem obvious considering we regularly exchange saliva when we kiss. A ten-second kiss alone can exchange up to 80 million bacteria. The more kisses a couple shares, the more shared salivary bacteria they will have.

Although most of these bacteria will quickly pass through our mouth and into our gut when we swallow saliva, research show that couples actually share many of the same longer-term tongue microbes that form the foundation of the oral microbiome. Research even suggests that 38% of the oral microbiome is shared in couples living together – compared to only 3% in couples who don’t live together.

Sharing this proportion of your oral microbiome could have many potential health effects.

A healthy oral microbiome is important for protecting against tooth decay and it has anti-inflammatory properties. Some researchers also suggest the oral microbiome’s health effects may extend as far as the gut and nervous system.

But some of the bacteria that couples tend to share may also have potentially harmful health effects.

Couples are more likely to have similar numbers of the bacteria Neisseria in their gut compared to single people. Neisseria can reside in the mouth for long periods of without causing disease.

Some Neisseria bacteria can be harmful and may cause meningitis. Yet some Neisseria bacteria actually fight against these meningitis-causing species, stopping them from overgrowing and causing harm.

So while you may want to avoid kissing someone when they’re poorly for obvious reasons, it turns out that a kiss even when you’re healthy can transfer all sorts of bacteria between the two of you.

More research is needed to really understand what overall effect sharing these bacteria with your partner has on health.

Skin microbiome

The skin microbiome is the most unique and personalised microbiome, tailored to each person. It’s even sometimes referred to as our microbial fingerprint.

Being the most exposed microbiome, the skin microbiome has evolved to be adaptable to external factors such as the climate and cosmetic products. No matter what, these bacteria work hard to remain at an equilibrium.

Close contact with our partners – and even pets – has a huge influence on what bacteria live on our skin. After comparing the gut and oral microbiome, researchers found the skin microbiome to be the most similar among couples.

It isn’t just the bacteria on your arms or hands that are shared, either. Research shows that couples shared 35% of the bacteria living on their feet, and around 17.5% of the bacteria on their eyelids.

You may not even need to touch your partner to have the same skin bacteria as them. Factors such as sleeping in the same bed and walking on similar surfaces are thought to explain why such a large proportion of our skin microbiome is similar.

This is because humans naturally shed bacteria in a similar way as dogs shed fur. We leave traces of our bacteria on everything we touch – and we also easily pick up bacteria from our environments.

The shared effect of living together on the skin microbiome is so great that researchers were able to use computer models to accurately predict 86% of cohabiting couples based off of their individual bacterial samples alone.

But while it’s clear that couples share much of the same skin microbiome, the health effect that this has is not currently known.

While sharing bacteria with your partner may sound alarming, there’s often no cause for concern. Bacteria teach our bodies how to fight infections, they help us digest foods and even produce key nutrients. The bacteria we share with our partners are often harmless and sometimes benefit our health rather than hindering it.

Conor Meehan, Associate Professor of Microbial Bioinformatics, Nottingham Trent University and Janelle Mwerinde, PhD Candidate, Skin Microbiology, Nottingham Trent University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→March 20, 2026

Raincoat no longer waterproof? A textile scientist explains why – and how to fix it

Alesia Kazantceva/Unsplash Carolina Quintero Rodriguez, RMIT University

You pull on your rain jacket, step out into the storm, and within half an hour your undershirt is soaked. The jacket you purchased as “waterproof” seems to have stopped working, and all the marketing claims feel a bit suspect.

In reality, the jacket probably hasn’t failed overnight: a mix of how it’s built, the exact level of water protection it offers, and years of sweat, skin oil and dirt have all played a part.

But there are a few simple ways you can care for your rain jacket to ensure you stay dry, even when it’s pouring.

The science behind rain jackets

Most proper rain jackets are built around a waterproof “membrane” sandwiched inside the fabric. Gore-Tex is the most popular technology used which includes a very thin layer of chemicals known as PTFE (polytetrafluoroethylene) or expanded PTFE (ePTFE) which are full of microscopic pores.

Those pores are much smaller than liquid water droplets. But they’re big enough for individual water vapour molecules, so rain on the outside can’t push through, but sweat vapour from your body can escape outwards.

Other fabrics use solid, non-porous membranes made from polyurethane or polyester that move water vapour by absorbing it and passing it through the material molecule by molecule rather than via tiny holes. This can make them a bit more tolerant of dirt.

The outer fabric is sometimes treated with a very thin chemical finish that makes water roll off the surface instead of soaking into the fibres – a bit like wax on a car. This finish is known as “Durable Water Repellent” and helps to reduce saturation of water in the exterior of the jacket.

In the past, many of these chemical finishes used “forever chemicals” (PFAS) that repelled both water and oil, but persist in the environment and build up in wildlife and people.

Because of this, brands and regulators have started using alternatives based on silicones or hydrocarbons. These still repel water but are generally less hazardous.

It’s also useful to understand the words you see on labels.

A waterproof jacket is built to stop rain coming through, even in heavy or prolonged downpours, and usually has a membrane, a chemical finish plus fully taped seams.

“Water resistant” means the fabric slows water down and copes with light showers but will eventually let water through. It often relies on a tight weave and a chemical finish but no true membrane.

“Water repellent” just describes that beading effect from the chemical finish. It can apply to both waterproof and non-waterproof fabrics.

Some brands also say rainproof or weatherproof as a friendlier way of saying “pretty much waterproof”, but there’s rarely a separate test behind that word.

 

The outer fabric of a rain jacket is sometimes treated with a very thin chemical finish that makes water roll off the surface instead of soaking into the fibres. Claudio Schwarz/Unsplash

Why do rain jackets degrade over time?

When you realise your jacket isn’t waterproof anymore, the first thing that has usually gone wrong isn’t the membrane. It’s the chemical finish on the outside.

That ultra thin surface layer gets scuffed by backpack straps and seat belts, baked by sun, and contaminated by mud, smoke and city grime.

These coatings can gradually lose their water repellent properties through abrasion and washing if harsh detergents and washing cycles are used, and bits of them are shed into the environment over time.

Body oils, sunscreen and insect repellent also play a role, as they build up in the fabric over time. Outdoor gear care guides and lab work on waterproof fabrics both point out that these oily contaminants can damage the chemical finish and clog the pores of the membrane, making it harder both for rain to be repelled and for sweat vapour to escape.

Over many years, slow physical ageing also takes a toll. Constant flexing can cause a membrane to thin or develop tiny cracks and the finish to deteriorate. Seam tapes can also start to peel away, especially on shoulders where backpack straps press.

How to keep a jacket waterproof

The single best thing you can do for both your comfort and the planet is to keep a good jacket working for as long as possible, because making new technical fabrics has a significant environmental footprint.

Gentle washing will help extend the life of your rain jacket, as it removes the build up of contamination such as dirt and body oils. Brands and care guides recommend closing zips and Velcro, then washing on a gentle cycle with a cleaner designed for waterproof fabrics or a very mild soap, avoiding normal detergents and softeners that leave residues.

Depending on the type of chemical finish, this coat can be re-applied through spray-on or wash-in products found commercially. Some finishes can be re-activated by exposure to low heat (low dryer heat or low ironing heat). Heat makes the water-repelling molecules stand back up after they have been “flattened” by use and contamination.

Although the above will help you to keep your jacket waterproof, it is best to follow the care instructions given by the manufacturer as they change according to the type of composition of the fabric.

In any case, it is important to avoid leaving the jacket wet and scrunched up for weeks, and be mindful of heavy sunscreens and repellents.

Carolina Quintero Rodriguez, Senior Lecturer and Program Manager, Bachelor of Fashion (Enterprise) program, RMIT University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→February 27, 2026

Why do nose and ear hairs become longer and thicker as we age?

Christian Moro, Bond University and Charlotte Phelps, Bond University

Growing older often brings unexpected grooming challenges. This is particularly apparent when some areas that, when young, we could otherwise ignore start to develop hair.

This includes our nose and ears, where hair grows thicker and longer as we age. But why do hairs in these areas act like this?

The answer predominantly lies in our sex hormones.

Two types of hair

There are two types of hair that grows across our bodies.

Vellus hair is fine and colourless. This hair (also called “peach fuzz”) grows across most of our body, including our arms and neck.

Terminal hair is stiff, thick and darker. It stands up from our skin and is usually very obvious. Adult males have terminal hair on about 90% of their body, with females growing it on about 30% of their bodies.

Terminal hair stands up when we’re cold (giving goosebumps) and helps trap heat to keep us warm. It also protects us from the sun (such as hair on our scalp), and keeps dust and dirt out of our eyes through eyebrows and eyelashes.

As vellus hair is smaller, thinner and colourless, it is not usually an aesthetic problem (although it can be altered in some diseases). Instead, it is the terminal hair that is often noticed, and the primary target of our razor.

The normal process of hair development involves a growth phase (anagen), follicle-shrinking phase (catagen), and then a short resting phase (telogen) before the hair falls out and is replaced as the cycle begins again. Some 90% of the hair on our body is in the growth phase at any given time.

Nose, ear, eyelash and eyebrow hairs don’t usually grow too long. This is because the growth phase of the follicles only lasts about 100–150 days, meaning there is a limit to how long they can get.

Alternatively, the hair on your head has a growth phase that lasts several years, so it can grow to more than one meter in length if you don’t get it cut.

Why do we have hair in our nose and ears?

We have about 120 hairs growing in each of our nasal cavities, with an average length of about 1 centimetre.

As you breathe through your nostrils, the hair in your nose works with the mucus to block and collect dust, pollen and other particles that could make their way to your lungs.

The hair in the ears also plays a protective role, trapping foreign objects and working with the earwax to facilitate self-cleaning processes.

What is the effect of ageing?

Androgens are a group of sex hormones that play a key role in puberty, development, and sexual health. The most common androgen is testosterone.

These androgens influence hair growth, and are the key to understanding why we have longer and thicker hairs in our nose and ears.

Hairs in different parts of the body respond to androgens differently. Unlike some hairs that are stimulated at puberty (such as pubic hairs and facial hair in males), some hairs, such as the eyelashes, don’t respond at all to androgens. Others increase hair size much slower, like the ear canal hair that can take up to 30 years.

Females have lower levels of androgens in the body, so major hair growth changes are more localised to the underarms and pubic regions.

We don’t have much data to support various conclusions about hair growth in later life, as most studies have focused on why we lose hair (such as balding) rather than why we have too much.

Nonetheless, there are still some hypotheses about why we grow more ear and nose hair as we age.

1. As we age, the body is exposed to androgens for a long time. This prolonged exposure makes some parts of the body more sensitive to testosterone, potentially stimulating the growth of hairs.

2. Over time, and long-term exposure to testosterone, some of the fine vellus hairs may undergo a conversion and become the darker, longer terminal hairs. This terminal hair then sticks out of our noses and ears.

3. Alongside increased levels of androgens as we go through puberty, a protein called SHBG (sex hormone binding globulin) is also released. This protein helps control the amount of testosterone and estrogen reaching your tissues. During ageing, the levels of SHBG levels may decrease faster than androgens, leaving testosterone to stimulate ear and nose hair growth.

4. Hair simply changes with age. This can result in changes in colour, thinning, and follicle alterations. There might be variations occurring in the follicles that respond to our body’s changing environment, stimulating longer hair growth.

Most of the impact of hairy ears and noses is observed in males, as they have larger amounts of testosterone.

Should we be worried?

It’s not usually a problem. Having a hairy ear (auricular hypertrichosis) does not appear to impact hearing at all. Note that if you are using hearing aids, excessive hair can impact their effectiveness, so in these rarer cases it is worth having a chat with your doctor.

The largest issue appears to be the appearance of these hairs, which can make some people self-conscious.

To address this, avoid plucking hairs out (such as with tweezers), as this can lead to infections, ingrown hairs and inflammation.

Instead, it is safest to reach for the trimmers (or employ laser hair removal processes) to clean up the area a little.

Christian Moro, Associate Professor of Science & Medicine, Bond University and Charlotte Phelps, Senior Teaching Fellow in Medicine, Bond University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→February 12, 2026

Winter Olympians often compete in freezing temperatures – physiology and advances in materials science help keep them warm

Cara Ocobock, University of Notre Dame and Gabriel R. Burks, University of Notre Dame

The Winter Olympics and Paralympics are upon us once again. This year the games come to Milan and Cortina d’Ampezzo, Italy, where weather forecasts are predicting temperatures in the upper 30s to mid-40s Fahrenheit (1 to 10 degrees Celsius).

These temperatures are a good deal warmer than one might expect for winter, particularly in a mountainous area. They’re warm enough that athletes will need to adjust how they are preparing their equipment for competition, yet still cold enough to affect the physiology of athletes and spectators alike.

As a biological anthropologist and a materials scientist, we’re interested in how the human body responds to different conditions and how materials can help people improve performance and address health challenges. Both of these components will play a key role for Olympic athletes hoping to perform at their peak in Italy.

Athletes in the cold

The athletes taking part in outdoor events are no strangers to cold and unpredictable weather conditions. It is an inherent part of their sports. Though it is highly unlikely the athletes this year will be exposed to extreme cold, the outdoor conditions will still affect their performance.

One concern is dehydration, which can be less noticeable, as sweating is typically less frequent and intense in cold conditions. However, cold temperatures also mean lower relative humidity. This dry air means the body needs to use more of its own water to moisten the air before it reaches the delicate lungs. Athletes breathing heavily during competition are losing more body water that way than they would in more temperate conditions.

When cold, the body also tends to narrow its blood vessels to better maintain core body temperature. Narrower blood vessels lose less heat to the cooler air, but this results in the body pushing more fluid out of the circulatory system and toward the kidneys, which then increases urine output.

Though the athletes may not be sweating to the same degree as they would in warmer temperatures, they are still sweating. Athletes dress to improve their performance and protect themselves from cold. The layers of clothing and material used in conjunction with the heat produced from physical activity can lead to sweating and create a hot, wet space between the athlete’s body and what they are wearing.

This space is not only another site of water loss, but also a potential problem for athletes who need to take part in different rounds or runs for their competition – for example, the initial heats for skiing or snowboarding.

These athletes are physically active and working up a sweat, and then they wait around for their next heat. During this waiting period, that damp layer of sweat will make them more vulnerable to body heat loss and cold injury such as frostbite or hypothermia. Athletes must stay warm between rounds of competition.

Science of winter apparel

Staying warm is all about materials selection and construction.

Many apparel companies adopt a three-layer system approach to keep wearers warm, dry and comfortable. Specifically, there is a bottom layer – in direct contact with the skin – that is typically composed of a moisture-wicking synthetic fabric such as nylon or a natural fabric such as wool.

The second layer in winter apparel is an insulating one that is generally porous to trap warm air generated by the body and to slow heat loss. Great options for this are down and fleece.

The final layer is the external protection layer, which keeps you dry and protected from the elements. This layer needs to be waterproof and breathable to keep the inner insulating layers dry but to simultaneously let out sweat. Polyester and acrylic are good options here, as they are lightweight, durable and resist moisture.

The gear athletes wear can be customized to their needs. For example, the synthetic fabrics used on the innermost layer are versatile, and engineers can introduce new properties and functionalities for users. Adding a specific coating to a fabric like nylon can give it new properties – such as wind and water resistance.

Frequently, both the synthetic fibers and the coatings materials scientists add to them are made up of polymers, which are long chains of molecules. They can be human-made and petroleum-based, like polyethylene trash bags, polyester and Teflon. But polymers can also be natural and derived from nature. Your DNA and the proteins in your body are examples of polymers.

In addition to polymer technology, conventional battery-powered heating jackets are also an option.

Smart materials

As an added bonus, there is also a class of smart materials called phase change materials that are made of polymers and composite materials. They automatically absorb excess body heat when too much is created and release it again to the body when needed to passively regulate your body temperature. These materials release or take in heat as they transition between solid and liquid states and respond to the body’s natural cues.

Phase change materials are less about warming you up. Instead, they work by keeping your temperature balanced.

While these aren’t commonly used in the gear athletes wear, NASA has been experimenting with them for a long time, and many commercially available products leverage this technology. Cooling fabrics, such as bedding and towels, are often made of phase change textiles because they do not overheat you.

Risks to the rest of us

Athletes are not the only ones at risk for cold injury.

While most of us will be watching the Games with the comfort of indoor heating, thousands of people and support staff will be watching or working those outdoor events in person. Unlike the athletes, these individuals will not have the added benefit of their bodies producing extra heat from exercise. The nonathletes in attendance will be at greater risk in the cold.

If you’re planning to spectate or work at an event this winter, drink more water than usual and time your bathroom breaks accordingly. Plan to wear several layers of clothing you can add and remove as needed, and pay special attention to the more vulnerable parts of the body, such as the hands, feet and nose.

Colder temperatures elicit a variety of metabolic responses in the body. One example is shivering, caused by tiny muscle contractions that produce heat. Your body’s brown adipose tissue – a type of fat – also becomes active and produces heat rather than energy.

Both of these processes burn extra calories, so expect to be more hungry if you’re out in the cold for a while. Trips to the bathroom or to get food are a welcome opportunity to warm up – especially those hands and feet.

It is easy to think of Olympians as exceptional athletes at the mercy of Mother Nature’s cold wrath. However, both the human body’s natural physiology and the impressive advances scientists have made in winter apparel technology will keep these athletes warm and performing at their best.

Cara Ocobock, Assistant Professor of Anthropology, University of Notre Dame and Gabriel R. Burks, Assistant Professor of Chemical and Biomolecular Engineering, University of Notre Dame

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→February 10, 2026

The science of weight loss – and why your brain is wired to keep you fat

When you lose weight, your body reacts as if it were a threat to survival. pexels/pavel danilyuk, CC BY

Valdemar Brimnes Ingemann Johansen, University of Copenhagen and Christoffer Clemmensen, University of Copenhagen

For decades, we’ve been told that weight loss is a matter of willpower: eat less, move more. But modern science has proven this isn’t actually the case.

More on that in a moment. But first, let’s go back a few hundred thousand years to examine our early human ancestors. Because we can blame a lot of the difficulty we have with weight loss today on our predecessors of the past – maybe the ultimate case of blame the parents.

For our early ancestors, body fat was a lifeline: too little could mean starvation, too much could slow you down. Over time, the human body became remarkably good at guarding its energy reserves through complex biological defences wired into the brain. But in a world where food is everywhere and movement is optional, those same systems that once helped us survive uncertainty now make it difficult to lose weight.

When someone loses weight, the body reacts as if it were a threat to survival. Hunger hormones surge, food cravings intensify and energy expenditure drops. These adaptations evolved to optimise energy storage and usage in environments with fluctuating food availability. But today, with our easy access to cheap, calorie-dense junk food and sedentary routines, those same adaptations that once helped us to survive can cause us a few issues.

As we found in our recent research, our brains also have powerful mechanisms for defending body weight – and can sort of “remember” what that weight used to be. For our ancient ancestors, this meant that if weight was lost in hard times, their bodies would be able to “get back” to their usual weight during better times.

But for us modern humans, it means that our brains and bodies remember any excess weight gain as though our survival and lives depend upon it. So in effect, once the body has been heavier, the brain comes to treat that higher weight as the new normal – a level it feels compelled to defend.

The fact that our bodies have this capacity to “remember” our previous heavier weight helps to explain why so many people regain weight after dieting. But as the science shows, this weight regain is not due to a lack of discipline; rather, our biology is doing exactly what it evolved to do: defend against weight loss.

Hacking biology

This is where weight-loss medications such as Wegovy and Mounjaro have offered fresh hope. They work by mimicking gut hormones that tell the brain to curb appetite.

But not everyone responds well to such drugs. For some, the side effects can make them difficult to stick with, and for others, the drugs don’t seem to lead to weight loss at all. It’s also often the case that once treatment stops, biology reasserts itself – and the lost weight returns.

Advances in obesity and metabolism research may mean that it’s possible for future therapies to be able to turn down these signals that drive the body back to its original weight, even beyond the treatment period.

Research is also showing that good health isn’t the same thing as “a good weight”. As in, exercise, good sleep, balanced nutrition, and mental wellbeing can all improve heart and metabolic health, even if the number on the scales barely moves.

A whole society approach

Of course, obesity isn’t just an individual problem – it takes a society-wide approach to truly tackle the root causes. And research suggests that a number of preventative measures might make a difference – things such as investing in healthier school meals, reducing the marketing of junk food to children, designing neighbourhoods where walking and cycling are prioritised over cars, and restaurants having standardised food portions.

Scientists are also paying close attention to key early-life stages – from pregnancy to around the age of seven – when a child’s weight regulation system is particularly malleable.

Indeed, research has found that things like what parents eat, how infants are fed, and early lifestyle habits can all shape how the brain controls appetite and fat storage for years to come.

If you’re looking to lose weight, there are still things you can do – mainly by focusing less on crash diets and more on sustainable habits that support overall wellbeing. Prioritising sleep helps regulate appetite, for example, while regular activity – even walking – can improve your blood sugar levels and heart health.

The bottom line though is that obesity is not a personal failure, but rather a biological condition shaped by our brains, our genes, and the environments we live in. The good news is that advances in neuroscience and pharmacology are offering new opportunities in terms of treatments, while prevention strategies can shift the landscape for future generations.

So if you’ve struggled to lose weight and keep it off, know that you’re not alone, and it’s not your fault. The brain is a formidable opponent. But with science, medicine and smarter policies, we’re beginning to change the rules of the game.

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This article was commissioned as part of a partnership collaboration between Videnskab.dk and The Conversation. You can read the Danish version of this article, here.

Valdemar Brimnes Ingemann Johansen, PhD Fellow in the Faculty of Health and Medical Sciences, University of Copenhagen and Christoffer Clemmensen, Associate Professor and Group Leader, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→December 16, 2025

Who invented the light bulb?

Ernest Freeberg, University of Tennessee

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.

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Who invented the light bulb? – Preben, age 5, New York City

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When people name the most important inventions in history, light bulbs are usually on the list. They were much safer than earlier light sources, and they made more activities, for both work and play, possible after the Sun went down.

More than a century after its invention, illustrators still use a lit bulb to symbolize a great idea. Credit typically goes to inventor and entrepreneur Thomas Edison, who created the first commercial light and power system in the United States.

But as a historian and author of a book about how electric lighting changed the U.S., I know that the actual story is more complicated and interesting. It shows that complex inventions are not created by a single genius, no matter how talented he or she may be, but by many creative minds and hands working on the same problem.

Thomas Edison didn’t invent the basic design of the incandescent light bulb, but he made it reliable and commercially viable.

Making light − and delivering it

In the 1870s, Edison raced against other inventors to find a way of producing light from electric current. Americans were keen to give up their gas and kerosene lamps for something that promised to be cleaner and safer. Candles offered little light and posed a fire hazard. Some customers in cities had brighter gas lamps, but they were expensive, hard to operate and polluted the air.

When Edison began working on the challenge, he learned from many other inventors’ ideas and failed experiments. They all were trying to figure out how to send a current through a thin carbon thread encased in glass, making it hot enough to glow without burning out.

In England, for example, chemist Joseph Swan patented an incandescent bulb and lit his own house in 1878. Then in 1881, at a great exhibition on electricity in Paris, Edison and several other inventors demonstrated their light bulbs.

Edison’s version proved to be the brightest and longest-lasting. In 1882 he connected it to a full working system that lit up dozens of homes and offices in downtown Manhattan.

But Edison’s bulb was just one piece of a much more complicated system that included an efficient dynamo – the powerful machine that generated electricity – plus a network of underground wires and new types of lamps. Edison also created the meter, a device that measured how much electricity each household used, so that he could tell how much to charge his customers.

Edison’s invention wasn’t just a science experiment – it was a commercial product that many people proved eager to buy.

Inventing an invention factory

As I show in my book, Edison did not solve these many technical challenges on his own.

At his farmhouse laboratory in Menlo Park, New Jersey, Edison hired a team of skilled technicians and trained scientists, and he filled his lab with every possible tool and material. He liked to boast that he had only a fourth grade education, but he knew enough to recruit men who had the skills he lacked. Edison also convinced banker J.P. Morgan and other investors to provide financial backing to pay for his experiments and bring them to market.

Historians often say that Edison’s greatest invention was this collaborative workshop, which he called an “invention factory.” It was capable of launching amazing new machines on a regular basis. Edison set the agenda for its work – a role that earned him the nickname “the wizard of Menlo Park.”

Here was the beginning of what we now call “research and development” – the network of universities and laboratories that produce technological breakthroughs today, ranging from lifesaving vaccines to the internet, as well as many improvements in the electric lights we use now.

Sparking an electric revolution

Many people found creative ways to use Edison’s light bulb. Factory owners and office managers installed electric light to extend the workday past sunset. Others used it for fun purposes, such as movie marquees, amusement parks, store windows, Christmas trees and evening baseball games.

Theater directors and photographers adapted the light to their arts. Doctors used small bulbs to peer inside the body during surgery. Architects and city planners, sign-makers and deep-sea explorers adapted the new light for all kinds of specialized uses. Through their actions, humanity’s relationship to day and night was reinvented – often in ways that Edison never could have anticipated.

Today people take for granted that they can have all the light they need at the flick of a switch. But that luxury requires a network of power stations, transmission lines and utility poles, managed by teams of trained engineers and electricians. To deliver it, electric power companies grew into an industry monitored by insurance companies and public utility regulators.

Edison’s first fragile light bulbs were just one early step in the electric revolution that has helped create today’s richly illuminated world.

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Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Ernest Freeberg, Professor of History, University of Tennessee

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→November 17, 2025

Why do giraffes have such long legs? Animal simulations reveal a surprising answer

Roger S. Seymour, University of Adelaide and Edward Snelling, University of Pretoria

If you’ve ever wondered why the giraffe has such a long neck, the answer seems clear: it lets them reach succulent leaves atop tall acacia trees in Africa.

Only giraffes have direct access to those leaves, while smaller mammals must compete with one another near the ground. This exclusive food source appears to allow the giraffe to breed throughout the year and to survive droughts better than shorter species.

But the long neck comes at a high cost. The giraffe’s heart must produce enough pressure to pump its blood a couple of metres up to its head. The blood pressure of an adult giraffe is typically over 200mm Hg – more than twice that of most mammals.

As a result, the heart of a resting giraffe uses more energy than the entire body of a resting human, and indeed more energy than the heart of any other mammal of comparable size. However, as we show in a new study published in the Journal of Experimental Biology, the giraffe’s heart has some unrecognised helpers in its battle against gravity: the animal’s long, long legs.

Meet the ‘elaffe’

In our new study, we quantified the energy cost of pumping blood for a typical adult giraffe and compared it to what it would be in an imaginary animal with short legs but a longer neck to reach the same treetop height.

This beast was a Frankenstein-style combination of the body of a common African eland and the neck of a giraffe. We called it an “elaffe”.

We found the animal would spend a whopping 21% of its total energy budget on powering its heart, compared with 16% in the giraffe and 6.7% in humans.

By raising its heart closer to its head by means of long legs, the giraffe “saves” a net 5% of the energy it takes in from food. Over the course of a year, this energy saving would add up to more than 1.5 tonnes of food – which could make the difference between life and death on the African savannah.

How giraffes work

In his book How Giraffes Work, zoologist Graham Mitchell reveals that the ancestors of giraffes had long legs before they evolved long necks.

This makes sense from an energy point of view. Long legs make the heart’s job easier, while long necks make it work harder.

However, the evolution of long legs came with a price of its own. Giraffes are forced to splay their forelegs while drinking, which makes them slow and awkward to rise and escape if a predator should appear.

Statistics show giraffes are the most likely of all prey mammals to leave a water hole without getting a drink.

How long can a neck be?

 

In life, the Giraffatitan dinosaur would most likely have been unable to lift its head this high. Shadowgate / Wikimedia, CC BY

The energy cost of the heart increases in direct proportion to the height of the neck, so there must be a limit. A sauropod dinosaur, the Giraffatitan, towers 13 metres above the floor of the Berlin Natural History Museum.

Its neck is 8.5m high, which would require a blood pressure of about 770mm Hg if it were to get blood to its head – almost eight times what we see in the average mammal. This is implausible because the heart’s energy cost to pump that blood would have exceeded the energy cost of the entire rest of the body.

Sauropod dinosaurs could not lift their heads that high without passing out. In fact, it is unlikely that any land animal in history could exceed the height of an adult male giraffe.

Roger S. Seymour, Professor Emeritus of Physiology, University of Adelaide and Edward Snelling, Faculty of Veterinary Science, University of Pretoria

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→November 14, 2025