Surviving 6 months of night
By Christina Karekla
Both Poles experience 6 months of daylight in summer and 6 months of darkness in winter due to the axial tilt of the Earth in regards to the sun. This means they get one sunrise and one sunset a year (what a rare sight!). You could spend your whole life in daylight if you switched from one pole to the next since they occur at opposing times! Of course a few places can be in twilight, depending on their location.
No sunlight causes many problems to the organisms living in these areas. Firstly, it causes the temperatures to drop down to -20 °C. Animals evolved a variety of adaptations and behaviours to survive or escape the frigid cold such as growing thicker layers of fat, fur or feathers for extra insulation, burrowing, hibernating or migrating. Animals living in colder environments such as the North and South Poles tend to be larger with shorter limbs and bodily appendages, consequently reducing their body surface to volume ratio and reducing heat loss.
Unique adaptations in the Poles:
- The Antarctic fox has evolved paws that prevent the cold from circulating through the body with a counter-current vascular heat exchanger meaning they are able to keep their paws at a lower temperature in comparison to the rest of their body minimising heat loss. In addition, their paws contain polyunsaturated fats that prevent frostbite.
- Animals such as Antarctic fish have eluded freezing to death by creating antifreeze proteins. When a small molecule of ice begins to shape inside the body, the antifreeze proteins bind to it, preventing the water around it from freezing and creating an ice crystal. Additionally, they lower the minimum temperature that ice is created from 0°C to about -1.9°C.
- Emperor penguins huddle up during the harsh winter to keep themselves warm (which may work a bit too well). Whilst inside the huddle their body temperature can rise to 37.5 °C. Eventually they need to release some body heat. For this reason they rotate between being outside the huddle blocking the ice-cold winds to inside being nice and toasty. They also breed during the winter so newly born emperors are born in summer when the ice breaks and they can learn to hunt.
Another problem with no sunlight is the difference in biological clocks. Nearly every organism’s body adapts to the 24 hour rhythm regulating their bodily mechanisms. Bees know when to visit each flower, diurnal animals wake up in the morning and nocturnal animals hunt at night. Most organisms in the Poles have adopted an arrhythmic behaviour since the sun rising and setting happens only once a year.
Humans that visit the Poles have found it hard to adjust. It is hard to sleep when the sun is out shining and is even more difficult to be in a constant night. Many have been affected both physically and mentally with sunlight causing negative health impacts since vitamin D is needed for bone health and a strong immune system. Mental health decreases since the days are dark and gloomy.
Humans living full time there have found ways to deal with constant darkness such as many cultural festivals, social involvement or simply activities such as skiing. Some even prefer winter over summer for views such as the Northern or Southern lights.
What about you? Could you live in 6 months of darkness?