How the Bdelloid Rotifer Lived for Millennia — Without Sex

As a child, I always wanted a microscope.

I would have collected slimy waters from the scum ponds and murky puddles near my house. I would have brought them home and exposed them to the light of my microscope. I would then have peered deep into a secret world, where shady characters and alien forms lurked and traded.

It would be many years, when I was in college, before I finally witnessed this world—so alien, it might have inspired the science fiction books I wrote later as an adult. As it turned out, I was led to pursue a Masters of Science degree, studying periphyton (microscopic aquatic communities attached and associated with surfaces like rocks and plants) in local streams in the Eastern Townships of Quebec.

Filamentous algae collected in Lake Ontario, ON (photo by Nina Munteanu)

While my work focused on how diatoms (glass-walled algae) colonized surfaces, micro-invertebrates kept vying for my attention. Water fleas (cladocerans), copepods, rotifers, seed shrimps (ostracods) and water bears sang across my field of vision. They flitted, lumbered, wheeled and meandered their way like tourists lost in Paris. But this wasn’t Paris; I’d taken the blue pill and entered the rabbit hole into another world…

Sketch of common zooplankton and phytoplankton (illustration by Nina Munteanu)

The Secret—and Dangerous—World of Micro-Organisms

Small Freshwater habitats are home to a highly productive and diverse collection of micro-invertebrates—multicellular animals that can barely be seen with the naked eye. Many average from 0.5 to 1 mm in size and resemble little white blobs; however, a scholar can distinguish each invertebrate by its unique movement. For instance, when presented with a jar of pond water, I can usually distinguish among the wheel-like wandering of a gastrotrich, dirigible-like gliding of an ostracod (seed shrimp), the vertical goldfinch-style “hopping” of the cladoceran (water flea) as it beats its antennae, or the halting-jerking movements of copepods (oar-feet) as their antennae drive them along like a dingy propelled by an amateur oarsman.

Alas, puddles, ephemeral ponds and vernal pools pose sketchy habitats, given their tendency to appear and disappear in a wink. And like the thief in the night, they pose a harsh and uncertain home to many small organisms. These environments are ever-changing, unstable, chaotic and unpredictable. Yet, anyone who has studied these variable ecosystems understands that they team with life. 

When a puddle or ephemeral pond dries up then reappears with rain, how can these communities thrive? Or do they all die off and then somehow recruit when the pond reappears? Many of these invertebrates have evolved creative ways to survive in very unstable environments. Some form a resting stage—a spore, resting egg or ‘tun’—that goes dormant and rides out the bad weather.

Philodina, a bdelloid rotifer (microscope photo by Bob Blaylock)

Animalcules & the Bdelloid Rotifer

In 1701, Antonie van Leeuwenhoek observed that “animalcules” (likely the bdelloid rotifer Philodina roseaola) survived desiccation and were “resurrected” when water was added to them. He’d discovered a highly resistant dormant state of an aquatic invertebrate to desiccation.

Dormancy is a common strategy of organisms that live in harsh and unstable environments and has been documented in crustaceans, rotifers, tardigrades, phytoplankton and ciliates. “Dormant forms of some planktonic invertebrates are among the most highly resistant … stages in the whole animal kingdom,” writes Jacek Radzikowski in a 2013 review in the Journal of Plankton Research. Radzikowski describes two states of dormancy: diapause and quiescence. (on right: sketch of bdelloid rotifer by Nina Munteanu

Bdelloid rotifers can go into quiescent dormancy at practically any stage in their life cycle in response to unfavorable conditions. Early research noted that dormant animals could withstand freezing and thawing from −40°C to 100°C and storage under vacuum. They also tolerated high doses of UV and X radiation. Later work reported that some rotifers could survive extreme abiotic conditions, such as exposure to liquid nitrogen (−196°C) for several weeks or liquid helium (−269°C) for several hours. Desiccated adult bdelloid rotifers apparently survived minus 80°C conditions for more than 6 years. The dormant eggs of cladocerans and ostracods also survived below freezing temperatures for years.

Rotifers are cosmopolitan detrivores (they eat detritus) and contribute to the decomposition of organic matter. Rotifers create a vortex with ciliated tufts on their heads that resemble spinning wheels, sweeping food into their mouths. They often anchor to larger debris while they feed or inch, worm-like, along substrates. Some are sessile, living inside tubes or gelatinous holdfasts and may even be colonial. Rotifers reproduce by parthenogenesis (in the absence of mates), producing clones (like cladocerans). Resting eggs (sometimes called zygotes) survive when a pond dries up. Bdelloid rotifers don’t produce resting eggs; they survive desiccation through a process called anhydrobiosis, contracting into an inert form and losing most of their body water. Embryos, juveniles and adults can undergo this process. The bdelloid withdraws its head and food and contracts its body into a compact shape called a tun; a generally unprotected dormant state that remains permeable to gases and liquids. Like Tardigrades (see below), Bdelloid rotifers can resist ionizing radiation because they can repair DNA double-strand breaks.

The long-term survival and evolutionary success of bdelloid rotifers in the absence of sex arises from horizontal gene transfer via DNA repair.

In my eco-novel A Diary in the Age of Water the limnologist Lynna visits her technician Daniel as he peers through a microscope and makes the observation of why the bdelloid rotifer is well-suited to climate change:

I bent to peer through the eyepiece at what turned out to be a pond sample in a Petri dish. Attached to a pile of detritus shivering in the current, several microscopic metazoans—rotifers—swung like trees in a gale; they were feeding. Their ciliated disk-like mouths twirled madly, capturing plankton to eat. Watching them reminded me of my early research days as an honours undergrad at Concordia University in Montreal. Probably Philodina, I thought; I had seen many during my stream research in Quebec.

“They’re the future,” Daniel said, looking up at me with a smirk as I straightened.

I raised my eyebrows, inviting him to elaborate, which he cheerfully did.

“They’re the future because of their incredible evolutionary success and their ecological attraction to environmental disaster.” He knew he’d piqued my interest. “These little creatures have existed for over forty million years, Lynna. Without sex! And they’re everywhere. In temporary ponds, moss, even tree bark. Bdelloid mothers that go through desiccation produce daughters with increased fitness and longevity. In fact, if desiccation doesn’t occur over several generations, the rotifers lose their fitness. They need the unpredictable environment to keep robust.” They incorporate genes from their environment: they acquire DNA transposons—mobile DNA—through HGT.”

—A DIARY IN THE AGE OF WATER

The bdelloid all-female populations have thrived for millions of years by maintaining a robust and diverse population through epigenetics and DNA repair during dormancy…The dormancy of all-female bdelloids is an elegant technique to ride out harsh conditions. The bdelloids can go dormant quickly in any stage of their life cycle, and they’re capable of remaining dormant for decades. They can recover from their dormancy state within hours when the right conditions return and go on reproducing without the need to find a mate.

Highly variable environments tend to support rare species: organisms that are uniquely equipped for change. These are the explorers, misfits, and revolutionaries who do their work to usher in a new paradigm. They carry change inside them, through phenotypic plasticity, physiological stress response mechanisms, or life history adaptations. Like bdelloid rotifers going dormant through anhydrobiosis. Or blue-green algae forming dormant akinete spores. In tune with the vacillations of Nature, epigenetics-induced adaptation is the only option for keeping up with rapid and catastrophic environmental change, not to mention something as gigantic as climate change. That’s why the bdelloid rotifers survived for millennia and will continue for many more. They adapt by counting on change.

Maple swamp forest in Trent Nature Sanctuary, ON (photo and rendition by Nina Munteanu)

References:

Munteanu, Nina. 2020. “A Diary in the Age of Water.” Inanna Publications, Toronto. 300pp.

Munteanu, Nina. 2016. “Water Is…The Meaning of Water.” Pixl Press, Vancouver. 586pp.

O’Leary, Denise. 2015. “Horizontal gene transfer: Sorry, Darwin, it’s not your evolution anymore.” Evolution News, August 13, 2015. Online: https://www.evolutionnews.org/201508/horizontal_gene/

Ricci, C. And D. Fontaneto. 2017. “The importance of being a bdelloid: Ecological and evolutionary consequences of dormancy.” Italian Journal ofZoology, 76:3, 240-249.

Robinson, Kelly and Julie Dunning. 2016. “Bacteria and humans have been swapping DNA for millennia”. The Scientist Magazine, October 1, 2016. Online: https://www.the-scientist.com/?articles.view/articleNo/47125/title/Bacteria-and-Humans-Have-Been-Swapping-DNA-for-Millennia/

Weinhold, Bob. 2006. “Epigenetics: the science of change.” Environmental Health Perspectives, 114(3): A160-A167.

Williams, Sarah. 2015. “Humans may harbour more than 100 genes from other organisms”. Science, March 12, 2015. Online: http://www.sciencemag.org/news/2015/03/humans-may-harbor-more-100-genes-other-organisms

Nina Munteanu is a Canadian ecologist / limnologist and novelist. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books. Nina’s bilingual “La natura dell’acqua / The Way of Water” was published by Mincione Edizioni in Rome. Her non-fiction book “Water Is…” by Pixl Press (Vancouver) was selected by Margaret Atwood in the New York Times ‘Year in Reading’ and was chosen as the 2017 Summer Read by Water Canada. Her novel “A Diary in the Age of Water” was released by Inanna Publications (Toronto) in June 2020.

Ecology, Story & Stranger Things

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Illustration by Anne Moody, typology & design by Costi Gurgu

One of the lectures I give in my science fiction writing course and conference workshops is called “Ecology in Storytelling”. It’s usually well attended by writers hoping to gain better insight into world-building and how to master the layering-in of metaphoric connections between setting and character. My upcoming writing guidebook “Ecology of Story: World as Character” addresses this subject with examples from a wide range of published fiction. The book will be released in June/July of 2019 by Pixl Press.

In my lecture (and book) I talk about the adaptations of organisms to their changing environments. I describe the trophic (energy) relationships from producers to consumers and destroyers in a complex cycle of creative destruction.

Students perk up when I bring up some of the more strange and interesting adaptations of organisms to their environment: twisted stories of adaptations and strategies that involve feeding, locomotion, reproduction and shelter.

Purposeful Miscommunication & Other Lies

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Alcon blue butterfly and caterpillar with ant

For instance, the Alcon blue butterfly hoodwinks ants into caring for its larvae. They do this by secreting a chemical that mimics how ants communicate; the ants in turn adopt the newly hatched caterpillars for two years. There’s a terrible side to this story of deception. The Ichneumon wasp, upon finding an Alcon caterpillar inside an ant colony, secretes a pheromone that drives the ants into confused chaos; allowing it to slip through the confusion and lay its eggs inside the poor caterpillar. When the caterpillar turns into a chrysalis, the wasp eggs hatch and consume it from inside.

This reads like something out of a noir thriller. Or better yet, a horror story. Nature is large, profligate, complex and paradoxical. She is by turns gentle and cruel. Creative and destructive. Competitive and cooperative. Idle and nurturing.

Extremophiles & Anhydrobiosis

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Tardigrade on moss

When I bring in the subject of extremophiles, who thrive in places you and I would cringe to set foot in, students’ imaginations run wild with ideas.

I describe a panoply of weird adaptations in Nature—involving poisons, mimicry and deception, phototaxis and something called anhydrobiosis, which permits the tiny tardigrade to shrivel into a tun in the absence of water then revive after a 100 years with just a drop of water.

All this adaptation hinges on communication. How an organism or population communicates with its environment and among its own.

Examples of “strange” communication are the purview of the science fiction writer … and already the nature of our current world—if you only know where to look. The scope of how Nature communicates—her devices and intentions—embraces the strange to the astonishing. From using infrasound to chemical receptors and sensing magnetic fields. To allelopathy. Aggressive symbiosis. And so much more.

Talking Trees

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Dr. Suzanne Simard

UBC researcher Suzanne Simard, who has published hundreds of papers over 30 years of research, suggests a kind of “intelligence” when she describes the underground world “of infinite biological pathways that connect trees and allow them to communicate” In a forest.

This communication allows the forest to behave as if it was a single organism, says Simard. Her early in situ experiments showed solid evidence that tree species, such as Paper Birch and Douglas Fir communicated in a cooperative manner underground through an underground mutualistic-symbiosis involving mycorrhizae (e.g., fungus-root).

forest-conversing

mycelium connects trees underground

These trees were conversing in the language of carbon and nitrogen, phosphorus, water, defense signals, allelo-chemicals, and hormones via a network of mycelia. Fungal threads form a mycelium that infects and colonizes the roots of all the trees and plants. Simard compares this dense network to the Internet, which also has nodes and links—just as the forest.

Fungal highways link each tree and plant to its community, with busiest nodes called hub trees or mother trees. Calling them mother trees is appropriate, given that they nurture their young in the understory; sending excess carbon to the understory trees, which receive less light for photosynthesis. “In a single forest,” says Simard, “a mother tree can be connected to hundreds of other trees.” These mature trees act as nodal anchors—like major hub sites on the Internet—for tree groupings; according to Simard, they look after their families, nurture seedlings and even share wisdom—information—when they are injured or dying.

Fatal Attractions & Natural Bullies

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Bracken fern fronds

The “ordinary” Bracken fern thrives in a wide range of conditions on virtually every continent (except Antarctica). That’s because it plays the “long game” by having several strategies to outlive and outcompete its surrounding nemeses.

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The symbiosis of Bracken fern and ant

Strategies include a loose lifestyle such as several ways to reproduce and grow to accommodate seasons, drought and burning; a shady arrangement with the local thugs (aggressive ants) who protect it for its tasty nectar; use of cyanide and ecdysones by its young shoots; and tough carcinogenic fronds that contain glass-like silicates.

Despite its many uses by humans (e.g., used for potash fertilizer, heating fuel, roofing, bedding for animals), the Bracken fern is considered a pest. In truth, it is a hardy versatile adapter to changing environments. And that is what our climate changing world is fast becoming.

I highly recommend the works of Annie Dillard and Loren Eiseley for wonderful and bizarre examples of natural wonders that resonate with metaphor.

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Stream in coastal rainforest on Vancouver Island, BC (photo by Kevin Klassen)

I also recommend my upcoming book “Ecology of Story” (Pixl Press), which will showcase a diverse set of examples from the literature of metaphoric environment and creatures. “Ecology of Story” is due for release in Summer of 2019. Look for it on Amazon, Kobo, and a fine bookstore near you. Two other books in my writing guide series include: “The Fiction Writer” and “The Journal Writer“.

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nina-2014aaaNina Munteanu is an ecologist and internationally published author of award-nominated speculative novels, short stories and non-fiction. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books. Nina’s recent book is the bilingual “La natura dell’acqua / The Way of Water” (Mincione Edizioni, Rome). Her latest “Water Is…” is currently an Amazon Bestseller and NY Times ‘year in reading’ choice of Margaret Atwood.

 

Nina Talks Water with Grade 8 Students on World Water Day

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Nina talks with Valleys Senior Public School Grade 8 students about water

On World Water Day, at the kind invitation of Alene Sen (supervisor and coordinator for the City of Mississauga at the Mississauga Valley Library) I talked to some 100 Grade 8 students of Valleys Senior Public School about water. Several classes, in groups of about fifty students each, came at tandem to the library to learn something about water.

I had about half an hour to prime them with something that would spark their interest and which they could take home and think about—and possibly apply in stewardship.

carboniferous-paleozoic eraI started the talk by explaining that I’m a limnologist—someone who studies freshwater—and that water is still a mysterious substance, even for those who make it their profession to study.  After informing them of water’s ubiquity in the universe—it’s virtually everywhere from quasars to planets in our solar system—I reminded them that the water that dinosaurs drank during the Paleozoic Era is the same water that you and I are drinking.

We briefly reviewed some of water’s most interesting anomalous and life-giving properties such as cohesion and adhesion—responsible for surface tension and water’s capillary movement up trees. Below is an excellent 4-minute YouTube video “The Properties of Water” that describes these properties well.

I reviewed the circle of life and energy in an aquatic ecosystem and used the grey whale as an example to study trophic cascades and the balanced trophic cycle—with an endnote on the whale’s significant role in influencing climate.

I introduced each class to the incredible and very tiny Tardigrade, also known as the water bear or moss piglet, with magical properties of its own. The 4-minute TED video by Thomas Boothby is particularly instructive and entertaining.

I then showed the class an image of the Three Gorges Dam in China and reported how as a result of so much dam-building and retention of water—and because most dams are located in the northern hemisphere—we have slightly changed how the Earth spins on its axis. We’ve sped its rotation and shortened the day by 8 millionths of a second in the last forty years.

3-gorges dam

Water needs to constantly move. The Water cycle moves through the planet in all three forms (vapour, liquid and ice), over land and sea and through the earth, but also through all life. We are part of that cycle. We drink it and get immersed in it; we also breathe water in with every breath we take and breathe it out with every breath we exhale.

We are water; what we do to water, we do to ourselves.

I invited the class to discuss things we could do to help water as it moves through the planet. We talked about things we could do at home, with our friends, in our school and community to help water. Things like planting a tree in your back yard; adopting a nearby stream and taking care of it; organizing a beach clean-up; deciding to do something at home to waste water less.

Each action is a small thing. But that is how large things happen, through the accumulation of small things. And with every “small” action is a small shift in thinking, which leads to the kind of leadership that will change the world and make it a better place—for water and everything that depends on it.

After a discussion of the problems now facing water on the planet, we asked the students from The Valleys Senior Public School to answer the question “What can we do to help water?” on a small sheet of paper, which we then collected. Their responses showed great thought and a willingness to do something concrete. Alene created a billboard at the Mississauga Valley Library with the Valleys Senior Public School student responses to the question.

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Water Tree Display with student responses to the question: “What can we do to help water?”

Below are some examples of responses by students…

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Alene Sen and co-worker at the Mississauga Valley Library

Water Is-COVER-webYou can read so much more about water in my book “Water Is…”. Go see what people are saying about “Water Is…”

 

 

 

nina-2014aaaNina Munteanu is an ecologist, limnologist and internationally published author of award-nominated speculative novels, short stories and non-fiction. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books. 

A Tardigrade Christmas…

…A Different Christmas Story…

water bear03 copyBlika lived in Mossland with her clone sestras, gathering and sucking the delicious juices of detritus and algae. Never in a hurry, she lumbered from frond to frond on eight stubby legs in a gestalt of feasting and being. Blika led a microscopic life of bloated bliss—unaware of forests, human beings, quantum physics or the coming singularity…water bear010 copy

A sudden fierce wind wicked her water away. In a burst of alien urgency, she wriggled madly for purchase on the frond as it shivered violently in the roaring wind. Blika lost hold and the wind swept her into a dark dryness. Her liquid life-force bleeding away from her, Blika crawled into herself. The moss piglet felt herself shrivel into oblivion.

water bear08 copy

No, not oblivion… more like a vast expanse…

She had entered a wonderland of twinkling lights in a vast fabric of dark matter. Where am I?

It occurred to her that she had never thought such a thing before. Am I dead? She’d never thought about existence before either. What has happened to me? And where are my sestras? She felt an overwhelming sadness. Something else she’d never felt before and wondered why she hadn’t. Did it have to do with that liquid that had always embraced her with its life-force? Here, in the darkness of space, she felt alone for the first time, separated from the plenum.tardigrades_in_space copy

“Welcome, sestra!” boomed a large voice.

Blika beheld a being like her with eight arms and hands, seated on a throne and wearing a jeweled crown. “Why do you call me sestra?” Blika asked.

tardigrade-queen-by-thomas a gieseke copy“Because we are ALL sestras! You are a Tardigrade, aren’t you?” She waved all eight arms at Blika. “Well, I am your queen!” She looked self-pleased. “You are in Tunland now! The land of awareness. And now that you are self-aware, you can do anything! We’re special,” the queen ended in smug delight. The folds of her body jiggled and shimmered.

“Why are we special?” Blika asked.

“Because we are!” the queen said sharply, already losing patience with her new subject. “Don’t you know that you can survive anything? Ionizing radiation. Huge pressure. Boiling heat. Freezing cold. Absolutely no air. And no water…”

Blika gasped. Water was the elixor that connected her to her sestras and her world… her…home…

“How do you think you got here, eh?” the queen mocked her with a sinister laugh. Blika cringed. The queen went on blithely, “So, where do you come from, piglet?”

“I’m trying to find my way home…”

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“Your way? All ways here are my ways!”

“But I was just thinking—”

“I warn you, child…” The queen glowered at her. “If I lose my temper, you lose your head. Understand?”

Blika nodded, now missing her home even more.

“Why think when you can do!” the queen added, suddenly cheerful again. “First there is BE, then THINK, then DO. Why not skip the think part and go straight to the do part? In Tunland we do that all the time,” she went on cheerfully. “And, as I was saying, here we can do anything!”

The queen grabbed Blika by an arm and steered them through the swirling darkness of space toward a box-like floating object. “This is my doctor’s Tardis…”

“Doctor who?” Blika naively asked.

The queen shivered off her annoyance and led them eagerly through the door and into her kingdom.

tardigradetardis copyThey entered a strange place of giant blocks and whining sounds beneath a dark swirling sky.

The first thing Blika noticed was the huge tardigrades floating above them like dirigibles! Others were dressed in suits holding little suitcases and walking into and out of the huge blocks through doorways.

“We’ve crossed into another dimension—my universe,” the queen announced cheerfully. “Here you can do anything you want. So, why be tiny and feckless when you can be huge and powerful!” She studied Blika. “This is your moment to do what you could never do before. Think of the possibilities! You too could be huge!”

Blika stared at the strange world of smoke and metal and yearned for her simple mossy home.

tardigrade-helmet-1 copyAs if she knew what Blika wanted, the queen quickly added, “But you can never go back home!”

“Why not?” Blika asked, disappointed.

Because, that’s why!” the queen shouted.  Squinting, she added, “It’s too late. It’s just not done! Once you’ve learned what the colour green means you can’t erase its significance!”

“But I still don’t know what the colour green means,” Blika complained. “And, besides, I think you’re wrong. Becoming self-aware doesn’t stop you from going home. It just changes its meaning. And if I can really do what I want, then you can’t stop me. I’m going home to my family.”

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The little hairs on the queen bristled. Then she grew terribly calm. “I won’t stop you, but…” The queen pointed to the floating tardigrades above them. “My water bear army will. I sentence you to remain in Tunland forever for your crime!”

“I haven’t done anything…yet.”

“You’ve broken the law of thinking before doing. In Tunland you have to skip that part—”

“You just made that up—”

“Doesn’t matter!” shouted the queen. “Sentence first, verdict afterwards!”

“That’s nonsense,” said Blika loudly. “The idea of having the sentence first.”

“Hold your tongue!” said the queen, turning a shade of chartreuse.

“I won’t,” said Blika.

“Off with your head!” the queen shouted at the top of her voice, pointing to Blika with all eight of her appendages. The water bear army hovered over Blika, taking aim. They were going to get more than her head with those lasers, Blika thought, and scurried for cover faster than her stubby eight legs had ever moved before. She was doomed—

Then, just beyond her sight, she saw—no felt—something far more significant than the colour green…or a huge bloated water bear army about to shoot her…

Water! She could taste it, smell it, hear it. Blika rejoiced with thoughts of her green home.

i believeThe water came in a giant wet wave of blue and silver and frothy green. Tunland sloshed then totally dissolved. Blika surfed the churning water. That green! She knew what it was! Blika reached out with her deft claws and snagged a tumbling moss frond. It finally settled and there were her sestras! So many of them clinging to the same green moss! She’d found her family! She was home! Yes, it was a different home and different sestras, but it was also the same. Love made it so…

Merry Christmas!

 

water bear02 copyTardigrades, also known as water bears or moss piglets, are plump, microscopic organisms with eight clawed legs. Fossils of tardigrades date to the Cambrian period over 500 million years ago. Over 900 species are known. Tardigrades were first described by the German pastor Johann August Ephraim Goeze in 1773 and given the name Tardigrada, meaning “slow stepper,” by the Italian biologist Lazzaro Spallanzani. Tardigrades reproduce asexually (parthenogenesis) or sexually. They mostly suck on the fluids of plant cells, animal cells, and bacteria.

Tardigrades survive adverse environmental stresses including:

  • High and low temperatures (e.g., -273°C to +151°C)
  • freezing and thawing
  • changes in salinity
  • lack of oxygen
  • lack of water
  • levels of X-ray radiation 1000x the lethal human dose
  • some toxic chemicals
  • boiling alcohol
  • low pressure of a vacuum
  • high pressure (up to 6x the pressure of the deepest ocean).

Water Bear or TardigradeTardigrades respond to adverse environmental stresses through “cryptobiosis”, a process that greatly slows their metabolism. Tardigrades survive dry periods by shriveling up into a little ball or tun and waiting it out. They make a protective sugar called trehalose, which moves into the cells to replace the lost water. You could say that the water bear turns into a gummy bear.

Tardigrades have revived after a 100 years of desiccation. The antioxidants they make soak up dangerous chemicals and tardigrades can also repair damaged DNA from long term dry-out. In low oxygen, the tardigrade stretches out, relaxed muscles letting more water and oxygen enter its cells. The tardigrade’s cold-resistant tun also prevents ice crystals that could damage cell membranes.

Tardigrades survive temperatures, pressures and ionizing radiation not normally found on Earth. All this raises questions of origin and evolutionary adaptation. How—and why—have tardigrades developed the ability to survive the vacuum and ionizing radiation of space? Some suggest that it’s because they originated there. Scientists argue that they developed extreme tolerances from Earth’s volatile environments (e.g., water bodies that freeze or dry up, and undergo anoxia). But, if they can make it there, they can make it anywhere. So, where is “home” really?…

Water Is-COVER-web copyMy Book “Water Is…” by Pixl Press explores this creature and many other interesting things about water. Look for it on Amazon, Chapters, Kobo and in bookstores & libraries near you. If it’s not in your local library, ask for it.

 

 

 

nina-2014aaaNina Munteanu is an ecologist, limnologist and internationally published author of award-nominated speculative novels, short stories and non-fiction. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books.