The Insane Biology of: The Tardigrade

oh my God I'm on a hunt for the world's favorite and most mysterious microorganism one with eight legs and a reputation for invincibility supposedly they're everywhere they've been found on the tops of mountains at the bottom of the ocean in tropical rainforests Antarctica and maybe on the top of my moldy garage but tardigrades are more than just Charming and ubiquitous they are really intense if you've ever heard about tardigrades you've probably heard that they're invincible and there is some surprising truth to this certain species can survive being frozen to just above absolute zero and heated

to more than 149° C they can survive being completely dried out and have even survived going to space in these extreme conditions Tarter grades go into a sort of suspended animation and even after Decades of being in this suspended State they can be woken up as if nothing happened it's so unlike anything we see in our day-to-day lives that it makes scientists question the boundaries of what we consider alive versus dead and Beyond this perplexing resilience even the basic anatomy of tardigrades comes with its own puzzles most creatures in the microscopic World wriggle thrash or

have beating cyia or flagella legs are almost unheard of for creatures this small and the Mystery of tardigrade Anatomy only deepens when you learn about Marine tardigrades that have insane structures coming off their body that are as dazzling as they are baffling some look like flag poles others look like inflatable sticky feathers and for many of these structures we still don't know what they're for for an organism so prevalent in nearly every part of the planet tardigrades are still deeply mysterious why did this microscopic creature evolve to walk at all and what's with those crazy

morphological structures why are tardigrades thought to be invincible and could their incredible abilities one day allow them to colonize outer space and the harsh environment of [Music] Mars all tar R grades are aquatic animals requiring a film of water around their bodies to permit Locomotion and gas exchange however most of the tardigrades known to science are found on land in mosses and lyans all over terrestrial environments these tardigrades are known as limot terrestrial and are classified as UT tardigrades but you can't see them with the naked eye they are between 100 and 500 microns in

length and only visible under a microscope but luckily for me it doesn't have to be a very powerful one so having recently moved to a very wet Mossy environment I'm going to see if I can find one so the scientists told me that uh you can find Charter grades in mosses and lyans so I'm going to collect some Moss from this rock that I just found um Betty's going to help me you helping um and I'm going to put it in this petri dish and later we'll try to decant some tardigrades out of it the

origins of tardigrades appear to go back all the way to the Cambrian around 550 million years ago before land plants before the earliest ancestors of mammals before the dinosaurs basically tardigrades have been around for a long long time today scientists struggle to fit the tardigrade neatly into the evolutionary tree they're in their own film called tardigrada and there is still much debate about whether they're more closely related to arthropods or to nematodes PhD student Mark mapalo considers himself a Paleo gridlist and has special interest in studying ancient tardigrades the oldest fossil tardigrades that we are

sure is a tardigrade is actually around the Cretaceous it's dated around the Cretaceous which is like you know the time of the dinosaurs basically so it's it's 90 million years old and all of those stardog grade fossils are actually preserved in Amber so our hypothesis that this the star degrees are so small that the only way for you to actually preserve them or the highest chance of them being preserved in a fossil is in Amber Amber is fossilized tree resin you're probably familiar with the sticky resin that comes out of some trees when their bark

is injured now and in the past insects or tardigrades often get trapped in the substance and can't escape on occasion some of these ancient Globs of resin fell in water and ended up becoming buried in the sediment as it settled deeper and deeper into the Earth the pressure and temperature began to rise over Millennia these conditions caus the resin's compounds to polymerize where they turn hard and glassy whatever organisms were trapped inside the resin insects plants or tardigrades can be preserved with extraordinary Fidelity unfortunately the DNA of ancient tardigrades isn't preserved because DNA is fragile

the very oldest traces of it we've ever found are only 2 Mill ion years old but much of tardigrade Anatomy is preserved in the Amber and even though the oldest tardigrade fossil is 90 million years old it still very much looks like a modern tardigrade you would see it and it's actually like still looked the same as living it's just like amazing how basically their external morphology did not really change that long and that's because the tardigrade body plan is remarkably effective at the head they have mouth-like organs equipped with piercing stylets they use these

freaky little tongues to pierce the cell walls of Plants algae and fungus they esophagus then sucks the food in and the nutrients spread from their digestive tract to the rest of the body but some tardigrades eat more than just plants and fungus some are predators that consume entire living organisms such as rapers nematodes and even other tardigrades predatory tardigrades can even have a significant impact on the biodiversity of other micro animals around them scientists found that hungry tardigrades will eat up to 56 nematodes a day in certain conditions and this can be really beneficial to

the soil quality if those nematodes are pests who parasitize plants also on the first body segment some species of tardigrade also have very basic eyes made of just a handful of visual cells that allow them to detect light but like with everything else with tardigrades we're not exactly sure that's the whole story recently scientists identified multiple R opsins in tardigrades that were associated with vision but these opsin didn't seem to help them with color vision as they might in other animals weirdly they weren't even really active in the adult tardigrades these opsin were most active

when the tardigrades were still eggs what on Earth eggs need visual options for no one has any idea next on the tarr's body are the three trunk segments all of which have a pair of legs on either side and claws on those legs and the fifth and final segment of the body has a pair of legs that face backwards it's thought that the orientation of these legs helped the tardigrades grip onto things almost like a prehensile tail and the existence of all of these legs make tardigrades really strange microscopic animals the size of tardigrades rarely

have legs and if they do they aren't used for walking water fleas for example have legs but they're used for swimming and sweeping food into their mouths rotifers of similar size swim or inchworm along their substrate and roundworms sort of just wiggle around walking in this microscopic domain is kind of unheard of one reason it might be so rare is because walking in water while being so small requires overcoming a ton of viscous forces it would be like walking through honey for us tardigrades also have to overcome an extremely variable environment moving through syrupy water

climbing over piles of sediment or through clumps of tangly plant matter yet tardigrades used their eight stubby legs to walk through all of this with ease the world over does the smallest legged animal have some unique method of using their legs to overcome these obstacles to find out scientists looked at the Gate of tardigrades with specialized cameras they found that when tardigrades walk slowly they lift one foot at a time as they speed up they lift two feet that are diagonal from each other across the body keeping 4 feet on the ground and as they

go even faster 3 ft are off the ground at once they keep a minimum of 3 ft on the ground at all times even at their fastest speeds not including the backward facing legs this differs from many fast vertebrate Gates like a horse's Gallop where all four feet come off the ground at once while the the tardigrade walking pattern may seem random to us it's actually not unique at all the scientists realized that despite having significant differences in size and skeletal structures this way of walking was very similar to insects like larger panarthropods such as

stick insects insects about 500,000 times their size and separated by about 20 million years of evolution but what's the benefit of this type of walking for stick insects always keeping three or 4 ft on the ground provides them great stability over pointy Jagged and variable twigs and branches for tardigrades keeping 3 or 4 feet on the ground May similarly help provide stability as they trudge through variable complex terrain so tardigrades can't run fast like a horse or a micro horse I guess so they're slow but most importantly they're steady this similarity between tardigrade walking and

insect walking was a surprising result and one that may point to the reason behind the existence of tardigrade legs in the first place it could be that arthropods and tardigrades share a common ancestor that had legs much like this nurly wired to walk with this pattern thus this could be a piece in the puzzle of tardigrade taxonomy putting them closer to arthropods than nematodes after all and further assisting tardigrades in their journey through thick and tangly environments are the claws at the end of their legs many tardigrades actually have complex double claws on each leg

which consist of two slender primary branches and two basil secondary branches which themselves have two or three hooks these hooks help the tardigrade hold on to the substrate so they don't get carried away the difference in the number of Claws and their shape is an important way that scientists can distinguish between different species and there's something else fascinating about all the cells that make up those claws legs and body segments of tardigrade every cell that makes up every one of these body parts is a cell that the tardigrade has always had tardigrades don't grow by

cell division like we do their growth occurs by enlargement of the individual cells rather than by cell division and adult tardigrades of the same species will all roughly have the same number of cells some with up to 40,000 this phenomenon is known as UTI it's possible that growth like this decreases the risk of cancer or other problematic mutations that arise during cell division with all of this incredible Anatomy combined tardigrades live basically everywhere in freshwater lakes rivers and ponds and on every single continent so if I were to get a microscope uh what do you

think my chances would be if I went out into the world to look for grades where are you right now if you don't if you don't me am in Connecticut in New England okay yeah well I would say there's a high chance of you finding tardigrade there I feel like I always find the tardigrades in New England I don't see it's kind of tardigrade shaped oh there's something moving oh oh what was that but as much as I'm struggling to find a terrestrial tardigrade there's another type that's even harder to find the Marine tardigrades terrestrial

tardigrades may be amazing but Marine tardigrades are like something out of a Dr Seuss hallucination Marine tardigrades are usually hetero tardigrades and they can be divided into three major ecological groups there's the species that live on the Slime of algae or the plates of barnacles and are sometimes known as ectoparasites there's the interstitial species which can be found in the top few centimeters of sand in the loral zone and and there are the deep sea benthic species Marine tardigrades are characterized by their calic sensory structures that are absent in ut tardigrades and many of these

structures are downright flamboyant you know how when you look at a if you look in a stream and you look at macro invertebrates in a stream they're cool but then you look on a coral reef and it's like whoa mind-blowing tardigrades are like that terrestrial and freshwater tardigrades are cool you look at Marine ones and they're mind-blowing Dr Paul Bartels has been studying tardigrades since 2000 and more recently started focusing on Marine tardigrades and I can totally see the appeal some of these tardigrades are truly spectacular like tartis bubalis which was found in the Atlantic

around the Pharaoh Islands it's got these posterior branches that come off the back end they branch and branch and branch and branch and then at each end there's these bubble like formations that can inflate or deflate and they can when they deflate they're like adhesive and when they inflate they can be buoyant and so it's this like Dr Seuss like character with these big balloons coming out the rear end and it's just crazy stuff like that and that's hardly the only oddl looking hetero tardigrade from the ocean some have adhesive claws some have wing-like structures

that are extensions of the cuticle some have long inflatable Tails one of the ones I'm really interested in is there an intertial one that's called uh bpes bul codus bpes are these ones with little suction cup toes and they live in the mostly in intital Sands the suction cups allow them to hold on to Shifty intital beach sand but they vary there's about 40 species it's the most speos of all the Marine tardigrades and one thing that they clearly vary in from species to species is their coddle structures one of them that one of my

students found near her home in the Outer Banks of North Carolina has this tail that is like it's like a flag pole at the end of the body it sticks up almost vertically from their rear and at the end of the tail there's this big membranous bubble like a balloon but what are these ridiculous structures for for some things scientists have a decent idea some of them are um kind of thick paddle-like structures and some of them more filamentous hairlike structures and we know that at least on some of the paddle shaped ones they have

a pore at the end so presumably I think there's pretty good evidence that those are um chemosensory and the hairlike ones are probably tactile and for the crazy looking coddle structures like the flag pole for things like this there is less certainty one theory is that it helps them hold on tighter to their substrate like an anchor but the flag pole isn't mucusy and sticky like the feathers of tartis bubalis so it might not actually stick very good it could be that it gives them some buoyancy they don't Marine tter grades don't have any larval

uh planktonic stage like almost all uh macroscopic marine animals do so they don't have an obvious way to disperse and yet in some cases we know they have pretty broad ranges and so maybe they're dispersing passively they don't swim no tardra swim they're all benic and living on the bottom but surely they get stirred up in the sediment and swept away with currents and so if you can stay up in the water column longer you're going to disperse further so maybe they have that has something to do with that I my my dream there is

to figure out how to cut off the tails of the of the bulock codus with the flag pole and then drop them and measure how fast they drop wouldn't that be a cool experiment but experiments like this come with a challenge for as hard as terrestrial tardigrades are to find that's even more so the case with Marine tardigrades what about the Marine ones are so much harder to study or harder to find yeah you got to have quite a bit of patience they can be really rare they're much smaller in size than um terrestrial ones

and you got to use a trick or two to isolate them from the sediment um namely something called the freshwater shock technique which is where you take a bucket of sand you pour a bunch of fresh water on it and they go into osmotic shock and release their grip on the sediments and it stuns them and then you can decant them through CVS and if you're studying the deeper living tardigrades it's even harder you have to scuba diive or have some other deep water collecting technique for this reason the vast majority of studies look at

intertial Marine tardigrades there's probably less than 10 of us in the world that are actively studying Marine tarder grades and so every place I've gone to do inventory type work on Marine grades we always find new species in fact they kind of get in the way it takes so much work you know to to do some sort of ecological question that you're interested in it you end up discovering all these new species that have to be figured out today there are more than a thousand species of tardigrades that scientists have discovered and based on where

we have and have not looked for tardigrades scientists believe that there are many many more to still be found so I'm from the Philippines basically I collected some mosses in the back of our building and started culturing this stard grades that I have and was able to create some monospecific cultures and and yeah and it turns out that species was like a new species so how many species do you think are still out there to be found is it in the tens or hundreds or thousands oh definitely I would I would I want to say

at least a thousand thousands of new species out there and I can't even find one individual uh it's got a little swimy guy guys but that's not a tter grade oh wait what's this oh it's cool uh not as hard a grade oh oh oh we've got movement Oh I thought I was just going to be a worm but then look oh my God you can totally see his little fies my first tardigrade tardigrades are often referred to as Invincible which is of course not completely true in their natural environment they're pretty likely to get

eaten or injured or die of old age but there is a reason they have this reputation in 1950 scientists demonstrated that certain tardigrades survived after exposure to -273 3° C close to absolute zero later experiments showed that these same species can survive briefly being heated to 150° C they can also survive being almost completely dehydrated how can this squishy little animal do any of this and what's the point why does a tiny little aquatic animal need to survive such extreme temperatures the overarching method for living through dramatic environmental changes es is called cryptobiosis this is

when the tardigrades go into what's called a ton State a sort of suspended animation to do this they shut their metabolism completely down to the point where they're very almost dead the fibers in their muscles lock into place a bit like rigor mortise and often they lose an incredible amount of water from their body up to 98% in some cases when there's not enough water or when it's too hot a tier grade will fully contract into this ton State and freezing temperatures trigger a slightly different ton State called cryo biosis here the tardigrades use ice

nucleating proteins outside of their cells to draw water out of them to prevent ice crystals from damaging them also aiding in this miraculous transition are a unique group of proteins called cytoplasmic abundant heat soluble proteins when the tardigrade undergoes stress like loss of water these proteins are produced and then condensed to form a network of filaments these create a gel-like substance that encases cells and provides them with structural Integrity without the pressure of water inside the cell the cells would collapse in on themselves in these realtime videos you can see the gel stiffen to provide

a structure that keeps the cells from collapsing when conditions return to normal the proteins are no longer produced and the gel breaks down the gr takes in water again and can wake up and in this ton State the shriveled nugget slows its metabolism to as little as 0.01% of its normal rate and even more impressive is that they can survive this state for decades researchers who collected Frozen Moss from Antarctica in 1983 stored the samples at -20° C for more than 30 years then the sample was thawed and two tardigrade were extracted from the sample

named Sleeping Beauty 1 and 2 they were given algae for food and closely monitored unfortunately Sleeping Beauty 2 woke up but died on day 20 but Sleeping Beauty 1 woke up after 9 days and it started crawling around the petri dish it didn't eat until day 13 but by day 23 it was actually laying eggs and continued to do so four more times given these results it's clear that the recovery process is not easy and that not all tardigrades survive they are not extremophiles like the bacteria that grow near hydrothermal vents in the deep ocean

and only some species of tardigrades can do this therefore tardigrades are considered extremo tolerant they can survive these states by going dormant but that's not where they Thrive tardigrades are often called the most Invincible animal but they don't even hold the record for the creature that can survive the longest in a suspended State just in the last couple years there's been a couple papers come out that kind of make tardigrades look like nothing you know right now the only tardigrades that we know for sure the the length of time that they've survived in cryptobiosis is

a matter of like 30 40 years maybe 50 in one study there were just two papers for rotifers there's a paper on rotifers and a paper on nimod that came out over the last couple years that were um looking at Siberian permafrost ice core samples that were dated to 26,000 years and 43,000 years ago and they found nematodes and rapers in those two ice cores and when they brought them back to to room temperature in water they came out of cryptobiosis successfully Tarter grades don't even come close to those numbers as far as we know

it's likely we just haven't found the evidence yet I believe it's only a matter of time before tardigrades are found um in those samples as well because we know biochemically they have at least as many tricks as the nematodes and the rivers have but why did tardigrades evolve to survive such extremes at all surviving absolute zero seems like Overkill it's likely because the tardigrade didn't evolve specifically for these scenarios but those are rather a nice side benefit that comes from what the tardigrade did evolve for scientists think that tardigrades evolved their extreme response to extreme

environmental changes in the seas and oceans of the very ancient world the ability to go into the ton state may have first appeared as a response not to dry places or super cold places or super hot places but to changes in salt level in the sea if they lived in the intertial area when the water around these ancient tardigrades increased in salt concentration the water inside the creatures would have been pulled out through their permeable cells by osmosis where water flows from low to high concentrated environments the tardigrades would need some way to manage the

way these changes in salinity dehydrated them the survival strategy they came up with is a ton state known as osmo biosis and this ability to survive overly salty conditions also became a way to survive completely dry conditions and as tardigrade started to populate sometimes temporary puddles and streams this became crucial and this dehydrated nugget State also conferred some resistance to the cold and to the hot allowing them to spread all over the world and often their hardiness allows them to be the first ones in new environments scientists sometimes refer to tardigrades as a pioneer species

which means they are often the first species in a harsh environment whether that's the cooled and hardened lava Fields after a volcanic eruption or the toxic degraded soils that result from coal mining the tardigrades start eating and mating and becoming prey for other micro animals all that behavior sets the stage for an ever increasing number of creatures to enter that environment so pioneering Tendencies incredible ability to survive almost anywhere for scientists these things lead to the next big question can tardigrades survive space or even one day colonize new planets space hypothetically is the final environment

to colonize one that almost no organism can withstand due to its vacuum and intense radiation but tardigrades are not most organisms so in 2007 scientists did the natural thing and yeed them up there the tardigrades hitch deride on the European space agency's Photon M3 Mission an unmanned mission that carried 40 different experiments into low earth orbit for 12 days including 3,000 tardigrades from two species they went up in their dehydrated chicken nugget State and were exposed to space vacuum in both UVA and UVB radiation the sun emits UVA UVB and UVC radiation on Earth UVC

rays are almost completely absorbed by the atmosphere which is a good thing because they're the most dangerous about 90 5% of UVB is absorbed by the ozone layer but there's still enough getting to the surface to cause sunburns UVA is the least dangerous but still slightly increases the risk of skin cancer for the experiments researchers exposed some tardigrades just to the vacuum of space and others were exposed to the vacuum of space along with UVA and UVB radiation and some were exposed to all types of radiation the tardigrade exposed to just the vacuum of space

did great those exposed to all types of radiation all died but some exposed to UVA and B did survive the tardigrades that survived these conditions represented the first animals ever to survive the combined exposure of vacuum Cosmic radiation and UV radiation in outer space and it's largely thanks to their damaged suppressor or dup genes the these genes code for a protein that can form a bubble wrap around their DNA ongoing studies suggests that by binding to DNA in the nucleus of cells dup acts as a physical Shield preventing radiation waves hitting the DNA it's the

type of thing that makes scientists think those genes could be applied as protective therapy to other animals even one day us scientists have even inserted the duub gene into human cells using a virus as as a carrier they then fired X-rays at these human cells they found that DNA in the edited cells was 40% less damaged than those without the inserted Gene it's a long way from practical use but a tantalizing look at how these genes might be used to protect astronauts going into space while mutant human tardigrade astronauts are a long way from being

engineered experiments tardigrade survival in space might also open up Avenues to space colonization Mars has long been eyed up as a potential second home for humans but it's cold unprotected from radiation and very very dry all things a Tarter grade can manage pretty easily we already know that moss and lyen who are also pioneer species like tardigrades can survive in very harsh environments researchers are investigating whether Genetically Enhanced versions of moss could grow in even harsher envir environments and still be good habitats and food sources for tardigrades if that were the case these could be

a starter pack for bringing life to new planets like Mars this is all theoretical for now and there remains one vital element missing that even tardigrades can't live without and that's water on Mars the little water that exists is trapped in ice or minerals in the surface of the planet but this wasn't always the case Mars used to be covered in expansive oceans and just a few days ago the perseverance Rover made a huge Discovery the robot came across a viny rock on July 18th that could change the course of science Forever The Rock has

evidence that water once ran through it and the Rover detected carbon-based molecules within the rock along with evidence that life sustaining chemical reactions may have occurred and most excitingly the rock is covered with what looks like leopard spots on Earth leopard spots like this in rocks are often a sign of fossilized microbes while we won't know for sure until the rock makes it back to Earth to be studied if evidence of microbes is found it's painfully exciting to wonder what those microbes would have been like would they have been similar to life on our planet

similar to tardigrades or nematodes or bacteria as we know it when the story broke I knew immediately that this would be the kind of story to get sensationalized and that many news articles were going to get the facts straight up wrong so to help me Wade through the headlines and find the best sources I opened up ground news the website and app designed to help you pull back the curtain on media bias and factuality on ground news every story comes with a visual breakdown of the political bias reliability and ownership all backed by ratings from

from three Independent News monitoring organizations and instantly I could see that yep the headlines were all over the place with some headlines claiming NASA scientists discovered actual life on Mars and others being misleading at best so I really appreciated the ground news headline summary of the story that said no NASA hasn't found life on Mars yet but the latest Discovery is intriguing so then knowing that I was about to head into a field of misinformation I wanted to select articles to read that would stay true to the science with ground news you can quickly scan

the headlines and see which articles are flagged as having low high or mixed factuality so when I'm needing to do research on a subject I can easily filter out the ones with mixed or low factuality giving me the most factual information on a given news story on top of this when writing these videos I need to be aware of the bias in the reporting if only the left or only the right is reporting on a story that's a pretty big red flag and is something I need to look into before I repeat that information myself

for this NASA and Mars story I could see that 43% of the sources lean left 29% lean right and 29% lean Center while this isn't a huge bias it is there and this information allows me to pause and make sure there is no ulterior political motive behind the stories I'm reading sometimes the bias is much worse and ground news helps illuminate blind spots with their aptly named blind spot feed another major science story right now is that the Earth just broke the record for its hottest day 2 days in a row and ground news shows

that this story is a major blind spot for the right with only 11% of sources on this story leaning right I particularly like browsing the blind spot feed which highlights stories that are disproportionately covered by one side of the political Spectrum it helps me to understand the motives and intentions of media outlets and makes me feel like I'm circumventing the wool that so many media Outlets are trying to pull over everyone's eyes ground news provides all the tools you need to be a critical thinker and at this particular moment in our history that has never

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