_{Ready... set... GO!}

From the expected Yaks and Goats to astonishing snakes and spiders, part 1 covered the incredible lengths animals will go to survive in extreme locations, either by accident like the snakes, or to exploit a niche with no competition.

The jumping spider came out on top, approaching almost the peak of the Himalayas, but as always, the smaller we go, the more extreme we get. Spiders aren't the end of the story.

Spiders

Ok, to get an idea of where we're going next, we need to continue with spiders. Many spiders _{(Ugh I've said 'spider' in my head so much that it sounds weird now)}have a wonderfully disturbing commute technique called ballooning, or kiting. Basically, they release some silk threads that act as a wind catcher, pulling them into the air to travel along the currents to a new, exciting unknown.

Typically, these spiders such as some crab spiders will only drift off for a few metres, but occasionally they get caught in an updraft or jet stream and get themselves on a first class flight to... up. Ballooning spiders have been found thousands of feet in the air, and even thousands of kilometres out at sea away from any land, being caught on ships' sails and so on. This is very likely how the Himalayan spiders managed to end up living so high in the first place.

_{A whole family of spiderlings launching into the air}

But these are not the only creatures that make use of wind power. Moth caterpillars and spider mites also use this trick, and aphids that have been seen at least 2.5 kilometres high in jet streams over England can be a major pest problem, spreading all over the place where nobody can stop them. These creatures evidently evolved the trick separately, meaning this method of dispersal is a pretty successful technique - despite the inevitable mortality rate that comes with random launching into the air.

Spiders, however, do take the crown for the height and length of these trips, but they don't typically spend much time up there, and it's not that high compared to the Himalayan bumble bees or yaks anyway. But. Other life takes this whole wind dispesal a step further:

Aeroplankton

_{This actually exists}

Yep, there's a name for a whole ecosystem of life beyond the mountain peaks, studied by aerobiologists. Life high up in the atmosphere includes:

...viruses, about 1000 different species of bacteria, around 40,000 varieties of fungi, and hundreds of species of protists, algae, mosses and liverworts.

Never underestimate the little guys, eh? And they aren't exactly rare either. Some scientists counted 5,100 bacterial cells, crossing over 300 families with over 60% still living and thriving, per cubic metre floating over the Caribbean.

Plant pathologist Andrew Schuerger is one of many exploring the life above us, and using NASA's ER-2 aircraft, he and his team managed to scoop up bacteria and fungi chilling out 20km above sea level. For perspective, the previous champion jumping spiders hide away in rocks barely 6.5km up. To top it off, actual living microbes have been recovered from 41km up in the part of the atmosphere we call the stratosphere.

But can they go higher?

The answer at this point is we don't know. But, as mentioned in the previous post, at a certain heights, things actually get warmer than in the thicker atmosphere below, and there is indeed a band of atmosphere called the stratopause (the band above the stratosphere and below the mesosphere) that is kind of like an altitude oasis partly thanks to aerosol particles that absorb solar radiation. Temperatures are still a nasty 0°C, but that's far warmer than below and above.

Note how the temperature fluctuates, indicated on the left

Trying to figure out the limits, Schuerger experimented with the common bacteria Serratia liquefaciens, and even a species found frozen in the permafrost of Siberia, Carnobacterium. He put them under even more unforgiving pressures and temperatures than the stratopause in an oxygen-free environment and found them to survive just fine - even continuing to grow. But this does not account for UV radiation which could destroy DNA of any potential microbes living this high (50-55km!).

The technology is on the brink of production to properly go up there and scoop some life up via NASA's E-MIST balloon or other upcoming techniques.

As usual, I wasn't...quite... satisfied with this. Most of this news came from 2013 and was very speculative as to the hows. So I did a little more digging and found a study from June this year looking at how certain bacteria survive UV stress so well You can find it available here.

Data from this study looked at one bacteria, Rhodobacter sp., a type of photoheterotrophic bacteria.

These organisms use light for energy, but cannot use carbon dioxide as their sole carbon source. They use organic compounds from the environment.

The results found that this bacteria had the ability to use different types of energy to find solutions to UV induced oxidative stress. The research also suspects that mutagenicity - the ability to use the chemical agent mutagen to advance DNA mutation - played a part in physical DNA protection and antioxidant osmoprotectants.

Phew, a lot of vocabulary. Basically, bacteria have clearly found ways to protect against and repair damage from harsh, upper atmosphere radiation. This combined with Andrew Schuerger's research into their ability to survive cold, oxygen-less, low pressure atmospheres means I personally have confidence that microbes can and will be found over 50km above earth.

If so, this leads into a whole new speculative topic; Panspermia, the potential of microbial life 'seeding' other planets. With billions of bacteria potentially skirting the edges of our planet, it only takes some solar wind or bits of meteor to smash into them, pushing them beyond the escape velocity of earth and into deep space (something that I already reported on as a real area of study a couple of weeks ago)

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Questions about how these organisms survive, high above against all odds are still plentiful, but understanding them may lead to numerous drugs and other medical applications such as... super effective sun cream? At the same time, a greater understanding of how pests - and even disease - can potentially spread is of utmost importance. Give a nod to the wonders of extremophiles, but an even bigger nod to those scientists trying to understand them!