The world’s deserts and arctic areas are unforgiving habitats; difficult living conditions and harsh climates characterize both. The animals living in these habitats exhibit adaptations that reflect the similarities and differences between both habitats. Camouflage is an important adaptation for animals in both of these wide-open habitats; but the animals living in deserts cope with temperature extremes differently than animals in the arctic do. Additionally, warm-blooded animals thrive in arctic habitats, while cold-blooded animals thrive in deserts.
An imaginary line circling the globe at about 66 degrees north -- termed the Arctic Circle -- marks the southern boundary of the arctic. Meanwhile, because of the planet’s major wind patterns, most of the world’s deserts occur on both sides of the equator, between 5 and 35 degrees latitude. Both habitats receive little annual precipitation; the Sahara desert receives less than 4 inches of rain per year, while the arctic receives slightly more -- sometimes as much as 10 inches of precipitation per year. Much of the precipitation in the arctic falls in the form of snow.
One dramatic difference between the animals of the two habitats is the type of metabolism prevalent in each. Endothermic -- warm-blooded -- animals thrive in cooler habitats than ectothermic -- cold-blooded -- animals do, and vice versa. Ectotherms such as insects, arachnids and reptiles are common in deserts and arid regions, while most arctic inhabitants -- primarily mammals and birds -- are endothermic. Animals of the arctic often have thick fur and fat layers to insulate them from the cold, which contrasts with the sparse and short fur of desert animals. Additionally, endothermic animals of the arctic have small ears, and short, bulky bodies -- an adaptation which reduces heat loss. Endothermic animals living in deserts often exhibit the reverse pattern, being tall, small-bodied and possessing large ears that radiate excess heat well.
Hiding in Plain Sight
Desert and arctic animals live in very exposed habitats -- both are devoid of trees. This provides limited hiding opportunities for the animals living in them; accordingly, excellent camouflage is a common hallmark of animals living in both habitats. Polar bears (Ursus maritimus) and arctic foxes (Vulpes lagopus) use their white fur to blend in with the snow-covered arctic lands. Likewise, desert animals, such as sidewinder rattlesnakes (Crotalus cerastes), javelinas (Tayassu tajacu) and coyotes (Canis latrans), are often light brown in color to camouflage with the desert landscapes. Rodents living in the arctic may tunnel beneath the snow to avoid detection by predators; similarly, sandfish (Scincus scincus) -- a species of small lizards -- burrow under the sand in the desert to avoid predators.
Changing with the Seasons
The arctic seasons are dramatic -- winter and summer produce much different surroundings for the resident animals. By contrast, most deserts have relatively stable temperatures that do not fluctuate much through the year. Additionally, the photoperiod, or the amount of light in a day, fluctuates widely in the arctic -- the summers feature nearly constant sunshine, while the winters are almost completely dark. Because of their near-equatorial distribution, the photoperiod remains relatively consistent in deserts. Arctic animals must adapt to these changing patterns -- many hibernate or become inactive during the winter. Some species, such as snowshoe hares (Lepus americanus) change their color throughout the year to match their changing habitat -- in the summer, they display brown and cream markings, while they adopt white coloration during the winter.
- World Atlas: Arctic Map
- United Nations Environment Programme: Latitudinal Desert Belts
- One World, One Ocean: The School: Polar Bear Adaptations for Extreme Cold
- Desert USA: Desert Animal Survival
- Animal Diversity Web: Crotalus Cerastes
- National Oceanic and Atmospheric Administration: Daylight, Darkness and Changing of the Seasons at the North Pole
- University of California, Berkeley: The Tundra Biome
- Animal Diversity Web: Ursus Maritimus
- Live Science: The Sahara: Facts, Climate and Animals of the Desert
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