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Surviving the Polar Regions: Animal strategies and adaptations
The polar regions are among Earth’s most unique environments
Characterised by low temperatures, limited food availability, harsh climates and extreme seasonality, it’s challenging to live in the polar regions. Species inhabiting the Arctic and Antarctic have evolved various physiological, morphological (structural), and behavioural adaptations to survive in these challenging conditions.
Where is the Arctic? Where is the Antarctic?
The Arctic is in the Northern hemisphere whereas Antarctica is in the Southern hemisphere.
Iconic Arctic species include the polar bear, Arctic fox, narwhal, walrus, and bearded seal.
In contrast, the Antarctic is home to species such as the leopard seal, Emperor and Adélie penguins, and rock ptarmigan (a medium-sized game bird).
Slow and steady is key to survival.
Temperature has a major impact on how fast species develop. A pattern of slow development rates has been observed among Antarctic marine ectotherms (species that rely on the environment to regulate their body temperature).
For example, the development rates of marine larvae are slower at low temperatures compared to those in temperate and tropical regions. This is likely due to lower temperatures reducing protein synthesis and folding, resulting in fewer functional proteins available for growth.
With the close link between metabolism and development, polar species tend to have slower metabolic rates and use up minimal energy. Antarctic Nototheniodei fish, for instance, have evolved with reduced quantities of red blood cells and haemoglobin , the protein responsible for transporting oxygen throughout the body.
This reduction in haemoglobin reflects their lower metabolic rates and oxygen demands compared to species in warmer, temperate climates. Slow metabolism and development are key to surviving with the limited food available in the polar regions.
How species cope with food scarcity in the polar regions
The polar regions experience dramatic seasonal shifts in solar radiation, with continuous daylight in the summer and nearly total darkness in the winter.
This is accompanied by blizzards, freezing temperatures and limited food availability.
During winter, reduced sunlight limits the growth of primary producers like phytoplankton and plants, which in turn affects the entire food chain. Additionally, the sea ice that forms over the Ocean restricts access to open water, where many marine animals feed. Snow cover makes it more challenging for land animals to access their food sources.
For some animals, these harsh winter conditions are too extreme, and they migrate to more favourable areas. For those that remain, many build up fat reserves during the summer and early autumn to prepare for the limited food availability.
In the Svalbard rock ptarmigan, for example, these fat reserves are primarily used during episodes of acute starvation rather than supplementing daily energy needs.
Some animals also exhibit surplus killing and hoarding behaviour in the summer, such as the Arctic fox. The fox has been observed storing food, with one cache containing as many as 136 seabirds.
Many animals will limit physical activity to conserve their energy and reduce their resting metabolic rate. This refers to the amount of energy the body uses at rest to maintain basic physiological functions.
Adult King penguins can go without food for up to one month. Meanwhile, chicks can endure fasting for up to five months during the subantarctic winter, losing up to 70% of their body mass while relying mostly on stored fat reserves.
Pregnant female polar bears accumulate up to 40% of their body mass as fat before entering dens in late autumn. Here, they hibernate through the winter to conserve energy during periods of food scarcity.
During hibernation, they refrain from eating, urinating, defecating, instead recycling urea to conserve protein and relying solely on fat reserves for energy. Polar bears also have an exceptional sense of smell. They’re capable of detecting prey from as far as 32 km away and seals beneath compacted ice from 1 km away.
Small invertebrates that live on the seafloor, or meiofauna, have adapted to polar environments by feeding on degraded organic matter, which remains available year-round.
In many Arctic marine mammals, the milk produced for their young is exceptionally rich in energy and nutrients, which is vital for the pups to survive in the harsh, cold environment.
How species cope with freezing temperatures
Air temperatures in the polar regions can occasionally drop to -60°C, while Ocean temperatures are close to freezing. To maintain a stable core temperature, organisms must employ strategies to minimise heat loss through conduction, convection, radiation, and evaporation.
One common adaptation is the evolution of a rounded body shape to reduce exposed surface area. For instance, walruses have a large, tubular body with minimal projecting extremities, such as visible ears or a tail, reducing heat loss through conduction and convection.
Many polar species develop dense fur for insulation, such as reindeer and caribou (also a species of deer), whose hollow guard hairs provide air-filled cavities for additional warmth. In marine animals, where fur offers little insulation value, a thick layer of blubber becomes essential for protection against cold seas. It also serves as a food reserve.
Many species have evolved sophisticated blood flow regulation systems in body parts exposed to the cold. In marine mammals, a network of blood vessels in the flippers operates as a counter-current heat exchange system. This is when warm blood flows to the flipper transferring heat to cooler blood returning from it. This adaptation allows them to conserve heat in critical areas while maintaining functionality in their extremities.
Moreover, both Arctic and Antarctic fish have independently evolved antifreeze glycoproteins, which are secreted into their blood to prevent the formation of harmful ice crystals. These compounds are produced during the cold winter months in Arctic fish and year-round in Antarctic fish.
Behavioural adaptations also play a key role in survival
Emperor penguins form large huddles in extreme Antarctic cold and wind, with groups consisting of hundreds of individuals. The penguins take turns occupying the warmer centre of the huddle, where ambient temperatures can reach 37.5°C, helping conserve energy and incubate eggs during the winter.
Snow place like home
Survival in the polar regions requires a combination of physiological, morphological and behavioural adaptations, enabling species to endure extreme cold, limited food availability and harsh climatic conditions.
As climate change continues to alter these environments, the ability of polar species to adapt will be crucial for their ongoing survival in an increasingly warming world.
Check out How Climate Change threatens polar species: Polar bears, Orcas and Narwhals, where we discuss the opportunities and challenges for animals in a changing world.