Discover how animals take on extremes of temperature and win
The adaptive techniques that animals use to survive the temperature changes in their environment are nothing short of extraordinary. Some creatures such as Arctic ground squirrels or brown bears choose to while away winter in a deep slumber, while others like caribou or Arctic terns embark upon epic migrations to warmer climes the moment things start to get really chilly. Then there are the hardcore stay-putters, the animals that have evolved some truly wonderful – and some downright weird – ways to weather the storm. Take the Arctic tundra’s musk oxen, for example; this grumpy beast has a shaggy coat made of hollow hair for warmth that hangs so low to the ground that it traps a layer of warm air beneath the animal. Couple this with a whole herd of huddling musk oxen and things get very toasty indeed. Physical adaptation is a key weapon against the cold. Animals such as many rodent species will bulk up during the summer months in order to have sufficient fat reserves to see them through the winter. Other animals, like Arctic foxes or hares, have developed thick fur that actually changes colour with the seasons to provide both warmth and camouflaged protection. Metabolic changes allow survival against all odds, as well as amazing chemical adaptations, like the icefish, which has antifreeze literally running through its veins. However, surviving the chill isn’t all about adapting to seasonal changes. There are some animals in ecosystems such as the deserts that have to survive the daily extremes of day-to-night temperature fluctuations, and have developed incredible methods of coping with both extremes.
Up in the hills, it takes more than just a thick coat of fur to survive in this harsh ecosystem. High mountains provide a unique ecosystem, and with that comes a set of unique challenges for the animals that live there. When winter falls, inhabitants have a few choices – one option is to wait out the worst of this energy expensive season and hibernate, like the marmot, which sleeps from October into April. The marmot’s body temperature and heart rate drop, as the little critter conserves precious energy until the weather warms. Other animals that stay awake through the winter will adapt their appearance. Some creatures, such as the rock ptarmigan, a chicken-sized bird found in rocky mountains of North America and Europe, changes colour for camouflage. Other animals, such as some deer species, will turn a darker colour. Although it stands out against the snow, the benefit is that darker colours retain more heat. When it comes to staying warm, energy is everything and size really matters. Small animals need to eat much more in order to stay warm as they lose heat fast. The mountain shrew must consume its own weight in food every day just to survive the chill.
The desert is well known for its hot, dry and dusty expanses of burning sand. Animals that live here have to deal with scorching temperatures of up to 50 degrees Celsius (122 degrees Fahrenheit) and deal with less than 250 millimetres (9.8 inches) of rainfall per year. However, the clear, cloudless conditions that heat the desert to such soaring temperatures during the day also mean that during the night, temperatures regularly drop below freezing. These extreme conditions make it a constant challenge for animals to maintain a safe body temperature and survive. One of the best strategies to escape both the heat and the cold is simply avoidance. Many small mammals will dig burrows in the sand to create a more manageable microclimate for themselves, while cold-blooded creatures will seek out sheltered spots in crevices or shadows of cliffs. Animals that are active during the day will be out and about at dawn, when the temperatures are at their coolest, but not in the frozen grip of night. Larger animals don’t dig burrows, but having a large body is actually beneficial in the desert – it takes longer to heat up. This makes it possible to stay cool for long enough until the sun starts to set. After this, fur can be fluffed up to insulate against the chill.
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