Introduction
The Earth is a special planet in the universe for a variety of reasons. The two most famous of these, of course, are the fact that the Earth has life and the immense variety of environments in which life thrives. Earth boasts an impressive portfolio of over 9 million different Eukaryotic Species (although only a small percentage of them have actually been studied), and don’t even get me started on prokaryotes. Life, particularly prokaryotic life such as Bacteria and Archaea, is just about everywhere, even if you can’t see it directly.
Every organism, no matter how different, is unified by a single common theme: the need to thrive, reproduce, and survive on whatever the environment provides. This can be as simple as giraffes having longer necks to reach food that’s high up in the trees, but it’s such a complex process that it has a whole field of study devoted to it: ecology.
As time progresses, we’re finding out more and more about how it thrives and how the world shapes it, and throughout our scientific studies, we’ve encountered some very bizarre ways in which life transforms. These are three of the craziest types of organisms that we’ve discovered on Earth and the odd ways in which they’ve learned to survive in this chaotic, complicated world.
Aliens ARE On Earth… You Just Haven’t Met Them Yet
At the present moment, we don’t know of any life forms that currently exist on other planets. Venus, for one, has a surface that is far too hot (Roughly 860 Degrees Fahrenheit) and far too pressurized (Similar to being 900 meters underwater). Our other planetary neighbor, Mars, is the polar opposite. It is incredibly cold (Around -81 degrees Fahrenheit) and has almost no pressure at all. Without a protective suit, most humans would die in a matter of seconds.
You’d assume that Mars and Venus are completely uninhabitable because organisms can’t thrive in those conditions.
And that’s true for some species.
But not all of them.
Enter: The Extremophiles. Consisting primarily of prokaryotes, the extremophiles (Or extremity-loving organisms) are unified by one key characteristic: they can thrive in all of the places that would kill humans in a matter of seconds. These are the little guys that really push the boundaries of life to its fullest extent. If the limitations of life are a prison, extremophiles are the masterminds who plan a daring and ultimately successful escape in a wide variety of ways. The most famous of these types, of course, is how life manages to break out of the Prison of Temperature.
Thermophiles, which are a type of extremophile that can survive unbelievably high temperatures, have been found to grow and reproduce extensively at up to 122 Degrees Celsius (251F) and remain alive at 130 Degrees Celsius (266F). That kind of heat would literally cook most humans to death, but surprisingly, this doesn’t apply to them.
So how are thermophiles able to get through these crazy conditions as if just taking a stroll for the day? Well, the most important part is their anatomy. Enzymes, which are the proteins in their body that help them accomplish various tasks, are built with more stable structures that allow them to experience enhanced Hydrogen Bonding. The use of hydrogen bonding and salt bridges (Basically, attractive interactions between different parts of the protein based on charge) makes it more difficult for the heat of the thermophiles to break the structure of the enzymes.
Another difference in these Extremophiles is their genetics; at high temperatures, regular DNA and RNA would be at significant risk of denaturing. This is a huge bullet to life’s survival, but extremophiles have successfully dodged it by simply making their DNA smaller. When the heat damages part of the thermophile’s DNA, the mechanisms that repair naturally can fix the problem more quickly, and thus preserve their genes for future generations. The need to fix DNA and RNA is also alleviated by the presence of a higher G+C content (The complementary bases in the DNA) that holds together the atoms making up the DNA more closely, thus helping to keep it more stable and preventing the risk of it falling apart.
The opposite is also true; organisms can also survive in environments that are extremely cold. (They are called psychrophiles) The lowest temperatures in which these psychrophiles can survive are around -20 Degrees Celsius, which is about -4 if you’re American.
You’ve probably guessed that because hot is the opposite of cold, these psychrophiles survive by doing the opposite of what thermophiles do. And you’d be right: while enzymes in thermophiles focus on increasing their rigidity, psychrophiles are more focused on increasing the flexibility of their enzymes. They contain fewer ions within their structure and have fewer attractions between the amino acids that make them up. This flexibility makes it easier for the enzymes to work at temperatures.
But the prison of life isn’t just limited to temperature; there are several other metrics that organisms have pushed to the absolute extreme. Acidophiles can survive in places of incredibly low pH by having pores in their cell membranes that have a net positive charge to repel the high concentration of Hydrogen Ions that threatens to enter and destabilize them every second. Alkaliphiles, the opposite of acidophiles, survive in incredibly basic environments by producing acids internally to neutralize the immediate external environment. Piezophiles (organisms that enjoy high-pressure environments) adapt by packing cell membranes with unsaturated fatty acids to keep them flexible under pressurized environments. Radiophiles (Survive in places with music— I MEAN, radioactivity) create several copies of their genome as backups stored in highly condensed nucleoids that contain damage in radioactive environments.
There’s even a group of organisms called Polyextremophiles, the most extreme of the extremophiles. These are the guys who survive many different extremities at once. And once again, these polyextremophiles are very important for our understanding of what life could be like on other planets. Other planets aren’t habitable to us, but there’s definitely potential for some of these bacteria to be able to survive and form colonies up there. Knowing how life adapts to the most crushing of stressors could be the gateway to our understanding of aliens and how they thrive on other planets.
Certain polyextremophiles, in particular, have been known to thrive on parts of Earth that parallel other parts of the solar system. Microbial ecosystems in Antarctica could serve as a template for the life that thrives on Mars, where temperatures and pressures are low. Halopsychrophiles (Thrive in salty/cold conditions) have also been discovered in Antarctica, which could use similar functions to survive that we find in a microbial colony that survives on moons like Europa (Jupiter) and Titan (Saturn). We haven’t discovered any extraterrestrial beings yet, but many of the diverse groups of prokaryotes out there definitely give us a glimpse into what aliens could look like.
The Most Bizarre Way To Give Birth
Many of Earth’s organisms reproduce in fairly simple ways. Some of them rely on each other, others can clone themselves using their own genetic information. Some organisms, like flowers, rely on animals to spread their pollen to other flowers. However, have you ever thought about “giving birth” as something explosive, where you’re launched into the air through complex fluid-pressure release systems designed to spread millions of tiny cells into the broader world? There’s so much offspring, in fact, that it literally looks like a cloud of baby fungi. Well, this is exactly what happens in the majority of fungi, a process called spore dispersal.
Spore dispersal is the main reproductive process that millions of fungi species utilize. While some fungi can reproduce asexually (essentially cloning their DNA), spore dispersal is used by the majority of fungi on Earth. So… how do fungi actually use spore dispersal? Well, two main types of fungi utilize sexual reproductive spores: Basidiomycota and Ascomycota.
These are differentiated based on their fruiting body structure, which affects how spores are eventually released into the world. The fruiting body is the thing that you usually see, such as a mushroom. It’s usually above ground and produces spores. Basidiomycetes produce their spores in the basidia. These are elongated, club-like cells on their fruiting body, where spores form on tiny projections called sterigmata. These basidia are where typically four spores and projections can be found, though exceptions exist. Mushrooms, gasteromycetes, jelly fungi, wood-ears, corticioid, boletes, polypores, coral fungi, and many more all use this type of spore production method.
Ascomycetes produce their spores differently. They have spore-producing cells called the asci, which are contained in the fruiting body. They are little “sacs” that hold the spores. Unlike basidiomycetes, the spores form within the ascus (singular for asci), rather than on outer projections. The asci typically hold 8 spores each, but some extreme exceptions have only 1 per ascus, while others can have upwards of hundreds per ascus. Cup, flask, and true truffle fungi all are all types of ascomycetes.
Now, there are two main ways in which fungi will disperse their spores. Actively and passively. The active methods can get quite complex, but there is often a mixture of the two in order to effectively disperse spores.
In basidiomycetes, active spore dispersal is launched like a miniature catapult. The spores using this technique are called ballistspores, and they have a tiny “spike” called the apiculus, which connects to the sterigmata. Its main component for launch? Water. The apiculus begins to secrete molecules of sugar, which water dissolves into, forming a water droplet. Water also forms on the surface of the spore. The center of mass shifts toward the apiculus, where eventually, the two water regions come into contact. This causes a rapid shift in the center of mass, as the water flows into the surface film, giving the spore large amounts of momentum. This is where passive transport comes into play, where wind carries the spores away from the host fungi.
Some basidiomycetes launch their spores in a widely different method.
In ascomycetes, active dispersion involves complex pressure mechanisms that launch the spores like a cannonball. The asci act as microscopic cannons, utilizing turgor pressure to launch the spore through the air and into wind currents. At maturity, the pressure forces the spores out of the top of the ascus, differing between species. Some let them out with a little “lid” that is forced to open, while others rupture the tip of the ascus, shooting the spores several centimeters outward. Many asci simultaneously shoot their spores out, creating large spore clouds.
Passive spore dispersal is often utilized in tandem with or alone from active dispersal. The most common method is utilizing wind to transport them. Both ascomycetes and basidiomycetes utilize some form of passive transport. Some rely on raindrops to condense the pressure in a sack of spores (in the basidiomycete puffball mushroom). Others rely on animal transport, mainly trying to be either carried or eaten. The spores of stinkhorns coat themselves in a thick, foul-smelling substance, attracting flies and other carrion insects. Truffle-like fungi simply make themselves look the most appetizing, emitting delicious aromas so that animals can dig up their fruiting bodies, later excreting the spores alongside their excrement far away from home.
Through all of these unique methods, fungi continue to survive and thrive among Earth’s complex ecosystems, being a wonder for us all to observe. Spore dispersal may even be a clue to how life can travel in space. Spores are highly durable, capable of withstanding heat, drought, UV radiation, and much more. Just like how spores sometimes hitch a ride on animals or forces of wind, which could give us insight on how life may survive on other planets. Spores in general could also be used in medicine, being used as drug delivery systems or dispersal systems.
The Tiny, Invisible Empire of Bacteria
It’s a pretty common misconception in society that humans are set apart from other species because of our ability to work with one another and function together as an organized community, or a society. In some ways, that is true; we definitely, as a species, have reached levels of sophistication that aren’t found anywhere else in the Animal Kingdom. We do, however, acknowledge pretty often that some decently sophisticated societies are formed by others in the animal kingdom, such as through ants, bees, and wasps that have very complex ways of interacting with one another and working to help each other survive in the wilderness.
Okay… so is that all? Is the ability to form societies limited only to species within the animal kingdom?
Nope! The Animal Kingdom produced the most well-known instances of separate organisms working together with one another to help survive, grow, and reproduce. But a less acknowledged way in which organisms collaborate is hidden in the depths of the microbial world.
Picture this: you have several bacteria in an environment where resources are incredibly scarce; the organic molecules that they typically feed off of are hard to come by, and as a result, chemical processes don’t happen that much, so the bacteria simply need to conserve energy. Some of the reactions involved with an organism’s metabolism are just too expensive for a bacterium to do on its own. In extreme places, this makes survival quite the challenge. But imagine that each of these bacteria, in proximity, works together to be able to facilitate the reactions they weren’t able to do beforehand. It works by having a group of bacteria consume the products of each other’s reactions, allowing for them all to survive.
Now, imagine you take that concept of bacteria systematically processing organic matter together as a group and expand it to the point that its scale extends far beyond the microscopic world. When you do that, you’ll find something eerily similar to how animals function and work together. This is an invisible civilization, and we call it the Biofilm.
These empires, which are hiding in plain sight, survive in a medium that they produce themselves, called the extracellular polymeric substance matrix. They attach to pretty much any surface they can find for stability, using a vast array of different biomolecules like polysaccharides, proteins, and ions (if you forgot what those are, re-read the Biometaphor on Macromolecules) to attach and communicate with each other. They even use DNA to stabilize the matrix and facilitate gene transfer.
This massive complex biofilm isn’t just some big, uniform, messy matrix of macromolecules holding everything together— it contains more parallels with human society than simply demonstrating that their organisms work together. It has layers and regions to it as well, like a whole civilization divided into different districts. The biofilm has its own water channel, functioning a lot like a highway system that allows it to move nutrients around like cargo on trade routes. Within larger biofilms, smaller groups called micro-communities evolve to interact by transferring their waste as reactants for another bacterium’s chemical reaction, akin to recycling. In a way, this is even more efficient than our society; it ensures that no molecule goes to waste at a time when resources may already be hard to come by.
Every empire that has ever existed on Earth has some intense lore and major figures that helped propel its growth into a thriving civilization; the Romans, for example, had Romulus and Remus. The Muslim Caliphates all started because of Mohammad and his first conquests, which snowballed into something much bigger than just a simple campaign. The life cycle of a biofilm, in a lot of ways, is parallel to the beginning of a grand civilization.
That story begins with the bacteria first finding a surface that will serve as the very foundation for the colony. They might not pick the first surface they find; usually, after first encountering a surface, the bacteria will attach to it with the flagella (the “tail” of the cell) using electrostatic attraction. This first attachment, however, can go backwards pretty easily. At this point, the pioneers of the future colony put the area through a sort of “test” to see if it’s worthy of being the starting ground for their colony. If bacteria find the surface unstable or the place is unfavorable, they can withdraw and continue searching for a new place to found their great empire.
If the area passes the test, then the bacteria begin to create more irreversible forms of attachment to the surface that they’ve chosen. Like the original British Colonizers of America building up their settlements, these pioneer bacteria have the complicated task of creating the big biomass that makes up a biofilm. They secrete these Extracellular Polymeric Substances as the building blocks for the colony. This is the part where that web of proteins (called Adhesins) starts forming to lock them in place and allow for communication between different species.
As they settle into their new home, the bacteria start growing in population and forming the systems in which they use their biochemical pathways in order to process nutrients. The concept of one bacterium using another one’s waste as its nutrients starts here (syntrophy) as they all start adapting to the new environment they’ve been introduced to. The colony grows and grows until it becomes a vibrant marketplace of different organic molecules that are all shipped through the advanced network of circulatory water channels, helping supply the micro-communities that need them the most.
The last step of the Biofilm life cycle, of course, is to spread out and plant the seeds for a new colony to form. Like the age of imperialism in the 1800s, the bacteria seek out new lands to control, spreading out (often with help from the external environment) and signalling to the rest of the mature biofilm to break away. This facilitates the restart of the new biofilm life cycle all over again.
These biofilms, in addition, are just about everywhere you look. In a lot of ways, they’re like extremophiles and can tell us a lot of insights into what life on other planets might look like, as the collaboration of bacteria has led to some pretty robust societies forming in places that probably wouldn’t be too friendly to the average human. Biofilms can be found everywhere— they’ve been discovered in the depths of the deepest caves and oceans, and there are even some weird types that can fuse way up in the sky in clouds or fog. And you thought that was only the domain of birds! (prepare to be potentially disturbed)
Oh, and they’re also inside you right now.
A lot of chronic diseases, about 80% or so, are actually the result of the formation of biofilms inside your body. Yep, that’s right; your body also happens to be one of the extreme habitats in which biofilms thrive. They’re all over, from the plaque on your teeth (Brush your teeth already. I know it’s been a good three days for you.) to your gut to the mucosa (the innermost layer of your organs) and in your food? Biofilms, although their scale might make them seem harmless, are a primary cause of health-related deaths.
They’re in your food, too! The empire of Biofilms also heavily affects human industries when they form in food production facilities, leading to disease outbreaks that come about as a result of the food. Their presence decays the quality of oil pipelines and messes up the hulls of ships, leading to issues in the production of goods around the world.
Humans have a really big impact on the Earth and its environment. We often like to think of ourselves as the powerful shapers of our planet. But these biofilms, these huge colonies of bacteria, form and cause huge problems for our healthcare and our economy. It really prompts us to ask the question: do humans really control Mother Nature yet, or does it still control us?
Conclusion
Living beings are constantly finding new ways of surviving and advancing themselves so that they can grow, thrive, and reproduce. This article has only covered the surface, but it really gives us a demonstration of how far life will go in order to make sure that it continues to push forward. This also, hopefully, gives some insight into how organisms may be able to survive on other planets.
Cody Nguyen, Tristan Chiu