It’s now January, which means that up here in the Northern Hemisphere, it is, generally speaking, the coldest time of year. The days are still short, barely rounding the bend from their shortest point on the solstice, and the sun cuts a tentative, shallow angle across bleak, sleepy skies, darting back under the horizon almost as soon as it emerged, as if it was trying to escape the nippy atmosphere and curl up under the warm cover of night.

The arrival into this annual temperature trough is sitting prominently in my mind these days for a variety of reasons:

1. My beloved Seattle Seahawks, just this weekend, made a miraculous win in Minnesota, despite enduring the full, sub-zero fury of the Gopher State, with windchill reaching a lung-punching 20-below, making it the third coldest NFL game ever.
2. The armed, self-described “militia” yokels currently more than a week and a half into squatting in the Malheur National Wildlife Refuge headquarters in my homeland of Oregon do so in a region of the state that suffers the most harrowing winter temperatures. A week ago, nighttime lows plummeted to 18-below (cold enough to turn the occupiers into Skoal-and-jerky flavored popsicles), and it hasn’t risen much since then, and won’t until March. There’s been some talk of cutting the power to the headquarters building, and simply waiting for the unyielding, unmitigated harshness of a high-desert January to bludgeon the everloving shit out of their seditionist tantrum.
3. I recently returned from a trip to Washington’s Olympic Peninsula to visit family for the holidays, during one of the most anomalously snowy and cold weeks of the year, with the snowline slumping down nearly to sea level, invading rainforest river valleys that are almost guaranteed snow-free throughout the winter. My soft, Hawaii-resident body whined in the face of 25 degree temperatures, atypical for a comparatively mild area of coastal Washington.

Even back in my normally balmy Hawaiian Islands, it’s now cold. And by “cold” I mean that I occasionally get the shivers waking up early in the morning with the windows open, and I don’t become a sweat-slicked heap of misery and heat exhaustion when just sitting in my home office. Basically, “cold” in Honolulu is when daytime highs top out short of 80 degrees Fahrenheit.

We tend to think these cold conditions, whether they are just a seasonal inconvenience, or a year-round way of life (like up near the poles), as being particularly insufferable for life. When the landscape is buried under five feet of Winnipeg white, the ecosystem functions very differently. Vegetation isn’t accessible to many herbivores. Predators have a minuscule pool of animals to hunt. The temperatures are too low for “cold-blooded” animals like amphibians and reptiles to stay active. Plant growth grinds to a crawl. Everything trying to scrape by in the frozen stillness seems to either be on the verge of starving or freezing to death.

The truth is, however, that while many organisms make a great effort to put up with or evade (ala songbirds flying towards the equator for winter, or mammals that hibernate) freezing temperatures…there are a minority that have embraced these glacial surroundings. Organisms that have evolved extreme levels of cold-tolerance sit at the lower boundary of what is possible for life to persist. Because of them, the coldest parts of our planet actually teem with life, even if it doesn’t appear that way during on initial impressions.

These elite lifeforms that would brush off a blizzard are often considered “psychrophilic.” The term essentially means “cold loving” and typically describes organisms that have specifically adapted to very cold conditions. This can mean that they reside their entire lives in freezing or sub-zero environments, or that they are capable of surviving and reproducing in temperatures far lower than what would turn other related species into a lifeless brick. In honor of the onset of the Northern winter, this two-part post will aim to examine some of our planet’s varied psychrophiles.

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If there’s one thing absent from the pale dread of winter, it’s insects, right? Well, save for the occasional stowaway bug that invaded your house when temperatures first started to drop and has been eeking out an existence on crumbs and dirt in the corner of your laundry nook ever since like a miniature Hugh Glass. Gone are the clouds of biting mosquitoes, the buzzing of grasshoppers, and the ever-ready millions of ants eagerly helping you “clean up” any left out food. For the six-legged, it appears as though winter’s harshness is an insurmountable force.

But, if you step out and away from the warm, indoor comforts, and take a plod in the snow on a sunnier, slightly warmer day, you might find something that will surprise you.

These little flecks of black may look like bits of soot blown in and scattered across the snow from your neighbor’s chimney, or like a mouse that ate a whole packet of laxatives just strolled by, but they are actually living creatures. If you were to stop and observe these wee eraser shavings for a while, many would bound and rocket around, making the surface of the snow look like the effervescent, dancing top of a freshly poured glass of soda. These dark snow sprites are called “snow fleas”, but their common name is misleading.

Snow fleas (Hypogastrura nivicola) are not fleas. And, to be completely honest, they aren’t even insects. Snow fleas are a variety of springtail, which are an order of arthropods in the class Entognatha, which is very closely related to, but distinct from, the class Insecta (which contains the several million species of insects we have crawling, buzzing, and skittering all over our planet). Springtails (order Collembola) and their entognath brethren are similar to insects in having three pairs of legs stemming from a thorax body segment, but differ by having internal, closed-off mouthparts instead of having them exposed (hence the name endognath; “endo” = inside, “gnath” = jaw). Springtails also do not have wings, but many species have a tail-like “furcula”, which looks a bit like a spatula, that they can fold under their abdomen under tension by tiny hook-like structures. When threatened, they then can release the furcula and allow it to slam against the ground, catapulting them the hell out of there. Many springtails only reach about a millimeter or two in length, and a majority of species are peaceful decomposers, munching on fungi, moss, and algae in relative secrecy. They are so small and so light, in fact, that they don’t break the surface tension of water and can rest on top of a puddle (they can actually form rafts that drift back and forth across the surface of a bit of water).

Snow fleas are somewhat unique in that they are very tolerant of frankly arctic temperatures, producing a protein that works like anti-freeze to keep their motor running in the face of incredible cold. Extreme winter cold will make them inactive, but it won’t kill the little guys. Snow fleas can be found in habitats all over the temperate Northern Hemisphere at any time of year, but their notably itty-bitty nature, combined with their habit of sticking close to rotting leaf litter and soil, while also being dark in color, makes them really damned hard to spot anytime outside of winter. One is far more likely to see them once they are against a white, snowy background.

Oh, and luckily for humans interested in finding snow fleas on a late-winter jaunt, snow fleas have a habit that makes them significantly easier to see….namely, clumping together in a squirming mosh pit made up many thousands of individuals, looking like what I’m sure a spillage of pepper must look like while frying on acid. The video below gives you an idea of how unsettlingly ginormous these aggregations can be, considering that all of this footage is taken right after the nice, white, contrast-inducing snow had melted away:

If you’re starting to sweat at the idea of legions of little charcoal grill-scrapings assembling to exact revenge upon the human race, do not fear. They pose zero threat to you and yours. Truthfully, more likely than not, these mobs of minute metazoans congregate for one very specific reason: fuckin’. Female snow fleas release an attractant pheromone when they’re fertile and ready to make feet for children’s shoes. Not only does this sweet-smelling love potion bring all the boys to the yard, but the femme fleas come in droves as well. What commences is an orgy feedback loop, with more and more fertile females amassing in one place, which magnifies the strength and reach of the procreation perfume, bringing in exponentially more males fixin’ to lay microscopic pipe until their hearts give out…along with even more pungent females. The end result is a snow pit full of grand-scale debauchery and the most hibbety-dibbety this side of an ancient Bacchanalian shagathon.

Gradually, the females in this sweaty, congested, literal clusterfuck become pregnant, cease making their bow-chicka-wow-wow pheromones, and abandon Bone-chella to go lay their eggs. Over the course of days or weeks, the whoopee cushion deflates as more and more snow fleas stop smashing pissers and return to their day jobs.

Huge numbers of snow fleas also come together to do something other than cumming together: to get their om-nom-nom on. The key to this is their weird life cycle. Insects molt (shed their skin) up until adulthood. Whether that means going through multiple miniature phases (nymphs) until reaching full-size, like mantises and grasshoppers…or the full-on metamorphic magic that turns grubs and caterpillars to beetles and butterflies, respectively…either way, the exoskeletal purging ceases in the adult form. But snow fleas, like all springtails, don’t go this route, and instead molt their entire life, switching back and forth between reproductive and feeding forms. One form capable of reproduction, but without the ability to feed….and one form that can eat, but can’t get it on. In times of food scarcity (like in winter), the feeding form may extend in duration, and collect in insane numbers near sources of food, which include things like tree sap, pollen, decaying leaves and other organic matter (and the fungus and bacteria doing the decaying), and nematodes.

There’s another nourishing treat that snow fleas are quite fond of, and groups of snow fleas can be seen grazing on patches of it on the snow like great herds of buffalo mowing down a rolling expanse of open prairie.

It’s red on white and cold all over. It’s “watermelon snow” and it looks like the lightly-aged remnants of a Yukon knife fight scene. Or the leftovers from when the 1st annual Rocket-powered Toboggan Race took an unexpected turn for the worst.

“Watermelon snow”, so-called for its obvious pink tinge (and, oddly, the melon-like odor it occasionally gives off), isn’t caused by gruesome spillages of blood, or chemical contaminants smeared across the wintry landscape (as was originally thought its origin). It is caused by a variety of unicellular green algae known as Chlamydomonas nivalis that grows on the surface of the snow, and down into the snow by as much as a foot.

It, like the snow flea, is a psychrophile. It’s closest relatives are typical freshwater alga, but this species likes its freshwater like Ed Gein liked his company: stiff.

The algae is common in regions that are freezing cold throughout the year. This can mean low-elevation or coastal areas near the poles, or alpine areas the world over…especially places where the snow lingers through the summer, not quite entirely melting by the time the autumn snows start again. I’ve personally seen small patches of it while hiking way up above 8,000 feet in the Central Oregon Cascade Mountains. Although the snow algae is capable of surviving the extreme cold of winter in these types of locations, it tends to hunker down and go dormant while being piled on with snow. When spring comes and the several month-long period of melting kicks off, the single-celled algae come out of hibernation and generate reproductive cells that wriggle towards the sweet, sweet life-giving sunlight closer to the surface. As the melting season progresses, the algae multiply, causing a bloom that makes the snow blush with many billions and billions of algal cells.

Chlamydomonas nivalis is a “green algae”, but is decidedly very not-green in color. The reason for this is that in addition to the normal chlorophyll pigments (the cool, colored compound that helps turn light energy into sugars), there is another reddish one: astaxanthin. Astaxanthin is pretty important in the snowy environment that the algae thrives in. As much as the icy surroundings fulfill the snow algae’s needs for low temperatures, they also are subjected to intense ultraviolet radiation. White things, like snow, reflect lots of sunlight in lots of different directions. This, combined with the bright sunlight experienced in high in mountain regions, compounds the ultraviolet radiation exposure to local organisms. The heightened level of reflected UV is enough to warrant extra eye-protection in anyone recreating in these snowy mountain environments, as to avoid the blisteringly agonizing effects of snow blindness…which is essentially a sunburn on the surface of your eyes. In the snow algae, that red astaxanthin works as a kind of sunscreen, keeping harmful levels of UV from damaging the cell by absorbing them. When absorbed, the UV radiation is converted into heat. When snow algae congregate densely in divots in the snow, the conversion of UV into heat by the algae can speed localized melting, deepening the hole. Over time, this can make “sun cups”; little, red-rimmed craters that pockmark the surface of a late summer snowbank. These rosy calderas look like some dude unzipped his snow pants to try to make “yellow snow”…but failed in the most distressing way imaginable.

If you’re thinking to yourself, “huh, that watermelon snow looks like a delicious, syrupy sno-cone that I should taste”, you may want to take a moment to knock that shit off. Some people contest that the algae-ridden snow even tastes like watermelon, and it can be enjoyed safely. However, lots of folks report significant levels of gastrointestinal distress (read: furiously crapping) after imbibing in a bit of sanguine slush. Apparently, the snow algae produce toxic by-products that effect the human digestive tract in varying degrees, depending on the person. Some people, like I said, aren’t affected at all, or only get a bit of gut pain when they eat larger amounts of watermelon snow. Others can take just a small, refreshing portion, and later that evening they’re holed up in the John with the chunky sputters.

So, unless you are prepared to deal with the potential, unpleasant consequences, I would think it would be wise to treat any pink snow you see like the yellow version, and abstain from putting it in your goddamn mouth. Then again, I’m not going to tell anyone how to live their life. Your colon, your decisions.

Snow fleas and snow algae are certainly model psychrophiles, flourishing in environments that would be devastating for many other organisms. However, there are other creatures on Earth that have freeze-avoiding powers that make the springtails and Chlamydomonas of the world look like thin-blooded snowbirds….

This post series will continue with Part 2, devoted to extremely freeze-proof insects.

Image credits: Intro image of snowy landscape (Caitlin Wynne), snow fleas on snow, pile of snow fleas, melting watermelon snow, sun cups, woman eating snow

© Jacob Buehler and “Shit You Didn’t Know About Biology”, 2012-2016. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Jacob Buehler and “Shit You Didn’t Know About Biology” with appropriate and specific direction to the original content.