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The Star
25-05-2025
- Science
- The Star
Clownfish, the main hero of 'Finding Nemo', shrinks to survive heatwaves, study finds
This photo provided by Morgan Bennett-Smith shows a clownfish inside an anemone. -- Morgan Bennett-Smith via AP As the marine world heats up, clownfish are showing an unsuspected talent for adapting to increasingly extreme conditions. Faced with heat waves exacerbated by climate change, these little fish, made famous by the movie "Finding Nemo,' adopt a surprising strategy to ensure their survival. In Papua New Guinea's Kimbe Bay, researchers from the Universities of Newcastle, Leeds and Boston, in collaboration with the Mahonia Na Dari Center, observed 134 clownfish (Amphiprion percula) over a five-month period. Each fish was individually identified and measured each month using a non-invasive capture device. Water temperature was recorded every four to six days using submersible sensors installed on site, enabling continuous monitoring of temperature changes during a marine heatwave. Their aim was to understand how these fish react to a sudden rise in water temperature. And the results were striking: 100 of the 134 clownfish decreased in size during the study period. A reaction that could increase their chances of survival by 78% during a marine heatwave. This discovery, published in the journal Science Advances, is a first. Never before has a coral reef fish been observed to shorten its body in response to environmental and social stress. Indeed, it's not just a matter of slimming down. "This is not just about getting skinnier under stressful conditions, these fish are actually getting shorter. We don't know yet exactly how they do it, but we do know that a few other animals can do this too. For example, marine iguanas can reabsorb some of their bone material to also shrink during times of environmental stress," says Melissa Versteeg, a PhD researcher at Newcastle University's School of Natural and Environmental Sciences, who led the study, quoted in a news release. This photo provided by Morgan Bennett-Smith shows a clownfish near an anemone in Kimbe Bay, off the coast of Papa New Guinea.-- Morgan Bennett-Smith via AP Shrinking together to survive together The researchers took care to measure each individual repeatedly, month after month. The extent of the phenomenon surprised them. This ability to shrink even seems to be coordinated between breeding partners, further increasing their chances of withstanding the heat together. This form of synchronization underlines the importance of social dynamics in the survival of the species. The morphological flexibility of these fish raises a broader question. What if this kind of shrinking explains why fish are becoming smaller overall in the world's oceans? For Theresa Rueger, a specialist in tropical marine sciences and coauthor of the study, this hypothesis merits further investigation. "Our findings show that individual fish can shrink in response to heat stress, which is further impacted by social conflict, and that shrinking can lead to improving their chances of survival If individual shrinking were widespread and happening among different species of fish, it could provide a plausible alternative hypothesis for why the size many fish species is declining, and further studies are needed in this area," she explains. In the underwater depths of a changing world, nature invents unexpected solutions to survive climate change, and clownfish teach us more than we might imagine about the resilience of species. - RelaxNews
NZ Herald
01-05-2025
- Health
- NZ Herald
The truth about bananas: Is the popular fruit actually good for you?
It's also worth remembering that 'while a very ripe banana will be easiest for the gut to digest, this is because it has the least starch, and an overripe banana has the highest sugar and lowest fibre and vitamin content'. Nutritional profile High in carbohydrates High in fibre High in sugar Low in protein Low in fat A medium banana contains around 100 calories, making it a conveniently portioned snack. In that, however, are 27g of carbohydrates, a full 10g more than can be found in a slice of white Hovis bread. A full 14.4g of that is sugar, with 3.1g of fibre. This same banana will come with around 1.3g of protein. So what are the pros and cons of making the fruit one of your five a day? The health benefits of bananas High in potassium Good for heart health Lower blood pressure Source of vitamin C Boosted digestion More energy 'Bananas are a good source of potassium, with one banana containing 451mg (around 10% of you daily needs),' says Weston. They're also low in sodium which, with their high potassium content, helps to control high blood pressure. We tend to reach for citrus fruits for vitamin C, but a medium-sized banana provides a respectable 10% of your daily vitamin C needs. 'Vitamin C is really important for bodies for a variety of reasons,' says Weston. 'It helps with immunity and maintaining normal skin, bones and cartilage. It also helps protect our cells and keep them healthy, as well as helping with wound healing and supporting our body when absorbing iron.' We all know the importance of fibre, and one medium banana provides around 10 to 12% of your daily needs. 'Traditionally bananas have been found to ease constipation, stomach ulcers and heartburn,' says Weston. Bananas contain three natural sugars – sucrose, fructose and glucose – giving you a fat and cholesterol-free source of energy. The mix of carbs and potassium is useful for exercise performance and muscle growth. 'This makes them ideal for athletes and children, they're great for breakfast as a midday snack or before and after sports,' says Weston. 'They're low calorie yet filling because of the aforementioned high-fibre content. They're rich in magnesium too, and a variety of antioxidants, such as flavonoids, which may reduce the risk of heart disease.' One study led by experts at the Universities of Newcastle and Leeds and published in the journal Cancer Prevention Research suggested that unripened bananas could have important implications in reducing cancers in the upper part of the gut. 'There is some research to suggest that the starch found in an unripe banana can reduce the risk of some cancers by 60 per cent,' says Weston. The cons of bananas Heightened potassium levels Wind and bloating Blood sugar spikes Potential weight gain Disrupted sleep 'Excess potassium may occur if you eat too many bananas,' says Weston. 'Having too much potassium in the body is called hyperkalemia.' As one Telegraph reader – with mild kidney disease – noted, his consultant told him to avoid bananas as 'even small amounts of potassium' can make kidney function worse. So if you have been diagnosed with reduced kidney function, it might be worth keeping an eye on your potassium intake. Dr Tom Oates, an NHS consultant nephrologist says: 'We do tell the advanced kidney disease and dialysis patients to be very careful of potassium.' He says that bananas, avocado and dried fruit are all high in potassium, so 'safer bets would be apples, pears and small citrus fruits like satsumas'. Advertisement Advertise with NZME. 'Some people may experience bloating or gas after eating a banana due to the sorbitol, a naturally occurring sugar alcohol that may act as a laxative,' explains Weston. 'People who are not used to a high-fibre diet may also experience some discomfort after eating a banana, such as cramping and bloating.' As one Telegraph reader observed: 'I have a couple of bananas every day, I was aware they are not great for greenhouse gas emissions.' The less ripe the banana the harder it will be to digest. 'This is because the carbohydrates are broken down into glucose,' says Weston. 'I would recommend pairing your bananas with a full fat yogurt to avoid this, or eating one after a balanced meal. 'If you have type 2 diabetes, bananas are OK to eat in moderation,' she adds. 'There is little evidence to suggest bananas can cause type 2 diabetes.' Yes, we are all constantly encouraged to consume more fruit, but like every food, overdo it and you will gain weight. As another Telegraph reader said, 'bananas are basically Mars bars in a yellow skin. Obesity is the main cause of essential hypertension.' Weston recommends limiting intake to 'no more than two bananas a day', adding: Advertisement Advertise with NZME. 'Bananas are a carbohydrate and contain sugar, so eating a lot of bananas and not pairing this with physical activity may lead to weight gain – but this is like most foods!' While they are clearly healthier than eating a biscuit with your evening cocoa, they are not the best snack to consume before bed it seems. 'Some experts suggest that a banana should be avoided before bed as it can cause restless sleep due to the high levels of melatonin (a sleep hormone) they contain, which can cause an imbalance,' says Weston. She does add, however, that if you do not personally find it affects your sleep, she would say it's not a bad bedtime snack option as 'a banana can be digested quickly'. In conclusion... Weston says that banana consumption is really an individual matter. 'If you like them, then enjoy them,' she says, though she wouldn't recommend eating more than two daily. 'Like any other food, you have to listen to your body and how it responds. If you personally find that eating them seems to disagree with you, or your digestive system, look at other ways to get the nutritional benefits they do clearly have.' FAQs Are bananas good for weight loss? It depends on your diet. 'As a good source of fibre, bananas help to keep you fuller for longer, so can help you lose weight by avoiding overeating,' says nutritionist Jenna Hope. 'But like anything else, if you eat too many of them then you'll gain weight, and eating bananas alone won't help you lose weight.' Is it okay to have bananas every day? Yes, but no more than one, says Hope. 'Bananas are high in natural sugar. There's no need to demonise them for that, but you shouldn't have more than one every day, though one per day is completely fine.' Do bananas have any benefits for hair health? Not particularly. ' Bananas are a good source of B vitamins which can support healthy hair,' says Hope. 'But they are not necessarily the best for hair health. Protein-rich foods and foods high in omega-3 and other healthy fats, like avocado, olive oil and almonds, are much better for hair health.'
