Top 10 Winter Warriors

Adapted to Harsh Winter Conditions

Winter is a challenging time for those of us who aren’t so fond of the cold. Every year we break out the heavy coats and scarves to keep warm, but what do animals do?

Let’s take a look a ten “winter warriors” of the animal kingdom with incredible adaptations to help them withstand the unforgiving winter elements.

Polar Bear

polar bear cub

Polar bear cub. Photo by tableatny via Flickr.

Polar bears live in the frigid north where winter temperatures average around -40 °F, but can sometimes drop as low as -92 °F (-69 °C). Thankfully, they have a few unique tricks up their sleeves to combat the cold. To start, those pretty white bears we love so much are not actually white! Polar bear skin is black, which helps them to retain heat by absorbing more of the sun’s rays. Their two layers of fur, on the other hand, are transparent and the longer outer layer is hollow and reflects light, giving them a white appearance. Under their skin is a layer of insulating fat up to 4.5 inches thick!

Wood Frog

wood frog

Wood frog. Photo by Ontley via Wikimedia Commons.

Wood frogs literally freeze during the winter months. They stop breathing and their hearts stop beating, but they produce a special glycerol-based substance that acts as antifreeze and prevents ice from forming within their cells. If the water within a cell were to freeze, it would expand and the ice crystals would tear the cell apart, killing the frog. Through this process, nearly 70 percent of the frog’s total body water is converted to ice. This adaptation allows the wood frog to surive even in the Arctic.

Wolverine

wolverine

Wolverine. Photo by Per Harald Olsen/NTNU.

Many of the species on this list are increasingly at risk from a changing climate, and the wolverine is no exception. These rare and elusive mammals have dense fur and snowshoe-like paws for walking on deep snow. They live within a “refrigeration zone” in high-altitude, snow-covered peaks. Wolverines also use the snow as a natural refrigerator to store food to get through the late winter and early spring. When temperatures rise and snow melts, they lose the ability to store food and may risk starvation.

Red flat bark beetle

Red flat bark beetle

Red flat bark beetle. Photo by Katja Schulz via Flickr.

Red flat bark beetles are extremely cold-tolerant. Similar to wood frogs, they produce high levels of glycerol in their blood which keeps the water in their bodies from forming ice crystals. In addition, red flat bark beetles also dehydrate their cells, allowing them to survive in temperatures in which the antifreeze chemicals alone wouldn’t be enough to keep them from freezing. Red flat bark beetle larvae have been recorded surviving in temperatures of -238 °F (-150 °C). That’s one impressive insect!

Reindeer

reindeer

Reindeer. Photo by Alexandre Buisse via Wikimedia Commons

Reindeer are masters of the tundra. Their hooves are like multi-purpose tools that act as snowshoes for walking, paddles for swimming, and shovels to help them dig for grasses. But even more impressive is the adaptation developed in their eyes, which turn from gold in the summer to blue in the winter to help them see at lower light levels. Imagine changing your eye color with the changing seasons!

Arctic woolly bear moth

Arctic woolly bear moth caterpillar

Arctic woolly bear moth caterpillar. Photo by Mike Beauregard via Wikimedia Commons

The Arctic woolly bear moth lives a unique lifestyle. As caterpillars, they will lie dormant when temperatures are below 59°F (15 °C). It only gets warmer than that in the Arctic for a short time each year, which means these caterpillars have a limited time to become active and to feed and build up the resources necessary to pupate. This means it takes approximately seven years for a caterpillar to successfully pupate into a moth. The Arctic woolly bear moth caterpillar also expels water from its body to prevent cell death in freezing temperatures.

Black-capped chickadee

black capped chickadee

Black capped chickadee. Photo by Minette Layne via Flickr.

Black-capped chickadees are about 5 inches long and weigh barely more than a Sharpie marker. So, how, you might ask, does an animal so small make it through winter in the northern U.S.? Aside from storing food and roosting in small, protective tree cavities, black-capped chickadees have two important biological adaptations: nocturnal hypothermia and metabolic regulation. During winter nights the chickadees will enter a state of hypothermia, effectively allowing them to lower their body temperature in order to store energy. This adaptation is complemented by the ability to increase their metabolic rate, which increases their heat production in order to accommodate winter temperatures. Together, these behavioral and biological adaptations make black-capped chickadees tiny but formidable winter warriors.

Lynx

lynx

Lynx. Photo by Keith Williams via Wikimedia Commons.

Lynx live in remote northern forests in North America. They have long, thick fur that acts as an insulating winter coat. Their large paws let them to walk on the snow with ease and allow them to silently stalk their prey. Lynx populations are dependent upon prey populations — particularly the nimble snowshoe hare — so adaptations like their impressive noses help them thrive. Not only do they have a powerful sense of smell, but their noses also help them determine the temperature so they can seek refuge before a storm hits.

Arctic fox

Arctic fox

Arctic fox

Don’t let their cute pointy ears and fluffy tails fool you; arctic foxes are tough! They have incredibly thick fur and a bushy tail that can wrap around them like a scarf, keeping their noses warm. Their short legs, ears, and snout help retain body heat, and the dense fur on the bottom of their paws prevents heat loss through their feet and helps them gain traction on the ice. Arctic foxes use their acute sense of hearing to locate prey deep beneath the snow, and refrain from drinking water in the winter as not to lower their core temperature. Instead, they get water through their food. Their metabolic rate only starts to increase at -58 °F (-50 °C) and they don’t start to shiver until temperatures reach -94 °F (-70 °C). Burrr!

Tardigrade

tardigrade

Tardigrade. Photo by Bob Goldstein and Vicky Madden, UNC Chapel Hill.

There are a number of impressive species on this list, but perhaps none more so than the tardigrade. This extremophile, affectionately called the “water bear” or “moss piglet,” is a microorganism no more than 1.5 mm long that is found in many ecosystems around the world, from mountain tops to rain forests to the deep sea. It can withstand temperatures ranging from -328 °F to 304 °F (-200 °C to 151 °C). It can even survive the vacuum of space! Tardigrades do this by undergoing a process called cryptobiosis, in which all metabolic activities halt. This would mean certain death for most animals, but not the tardigrade! It has the ability to reverse the cryptobiosis when conditions become more favorable, which is pretty darn cool.

 

Aren’t you glad you don’t need to adapt to these extreme temperatures? Unfortunately, that is not the case for our cherished wildlife. But you can help by sending a message to your Senators and Representative to oppose any rollback in measures that address climate change.

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