Last time I concluded the journey down to the deepest parts of the earth that life can endure, from deep sea diving whales to freaky fish and slugs, all the way down to extremophilic bacteria. Today we're gonna do the opposite and look up.

You'd think this would be easy enough, pressure doesn't nearly reach such high extremes in air, there's still obviously going to be sunlight and the icy tundras above are literally made of water. So what's the problem?

For the most part, it's the lack of air pressure. With an increasingly thinning atmosphere, animals need to adapt in very particular ways just so they can breath right. We're gonna work our way up and up, and you'll hopefully be as surprised as I was researching this, cause you'll never guess who the altitude champion is! _{It's pretty obvious}

The Himalayas

The best place to look into this is, of course, the highest place on earth. I'm particularly interested here since I spent a month there, trekking up to about 6,000 metres. The BBC covered a similar journey of life up the Himalayas but it was disappointingly brief in some areas so I had to dig a little deeper for satisfaction.

Red Panda

Starting at up to 4,000 metres, the über-cute red panda has made a bizarre choice. Sure, it eats bugs and eggs in the summer, but in the winter it thrives purely on bamboo, like the famous giant panda. This is such a stupid choice if you ask me. I mean, bamboo has barely any nutrition, is hard to digest (they only digest about a quarter of what they eat), and the red panda's body isn't even adapted to extract nutrients from it anyway.

Well, there's no magic going on. The panda doesn't somehow extract energy from the aether, but instead it has to slow its metabolism down to such an extent that it becomes comparable to the sloth. This also means that a good 13 hours or more of their day is consumed by the consumption and search of bamboo.

The one benefit that springs to mind for the panda and other extremists like this, is simply the lack of competition, which obviously works since they're still around!

Snakes

So we've gone up higher and higher and past some interesting plants, fish, even tigers and snow leopards, all the way past snub-nosed monkeys, red pandas and deer, all the way up to 4,500 metres.

At this point it's COLD. So it's no surprise that there are no cold-blooded reptiles here. Except there is. The Bailey's snake is a freak of nature endemic to Tibet. Again there's no magic trick here, and these snakes are found around the only sources of heat available: hot springs.

It's suggested their existence there

...might be an early adaptation to the cooling climate during the plateau uplift.

This is such a crazy thought, that the snakes had just been sitting there at the top of the mountains, desperately adapting as it rose closer and closer to the skies, finding refuge in the active hot springs. The genetic diversity is somewhat stunted due to mountain ranges and limited hot springs to thrive on, but they seem to be doing just fine once more!

Yaks

Further we go and we get to the highest living humans, Tibetans that have a unique genetic mutation that allows them to bypass all the problems with altitude humans typically have up here, from sickness to low fertility rates and death. Alongside these super-humans are the Tibetan Mastiff dogs who also mutated a gene or two to survive up here, having been by the side of the humans for the last 30,000 years or so.

It would be no surprise to me if we stopped here, humans having conquered every corner of the globe with our oversized brains helping us survive.

But nope. Beyond this at 6,100 metres we get a huge beast with exceptional adaptations; the Yak.

_{Damn, yaks are so cool.}

Immediately, you can see that the yak has a huge layer of fur to help it stay warm, and its size allows it to retain more heat than any small creature, but its what's inside that's so special.

Multiple genetic mutations allows for a bigger heart and lungs for obvious reasons, but the yak also lacks something called hypoxic pulmonary vasoconstriction, the process by which arteries constrict when in low levels of oxygen. By keeping the arteries open, it allows an increased potential of oxygen to get in.

But numerous genes focused on solutions to hypoxia - oxygen deprivation - and nutrition metabolism, among others. and by numerous, I mean the paper I'm reading describes 596 gene families that were 'substantially expanded' compared to other mammals, including nutritional pathways, fatty acid and amino acid metabolism and a whole bunch of fascinating changes you can read more about below.

Interestingly, the yak is so well adapted to these heights that it can be fatal for them to move below 3,000 metres, suffering from heat exhaustion and disease susceptibility.

But here's where things get particularly surprising. Remember when you read about 3 minutes ago that the yak's size gives it the advantageous ability to retain heat? So what about...

Spiders & Bumblebees

How can such little creatures survive these heights? Jumping spiders were found at 6,700 metres, and a whole colony of bees were found around the same height but were tested to have no trouble flying under conditions equivalent to 9,000 metres, expressing 'substantial aerodynamic reserves' and energy efficient adjustments to flight patterns.

For carnivorous food, the spider has to feed on dead stuff that blows upwards from below, but this enough to make it a permanent resident up here, possibly making it the highest permanent animal the earth has to offer.

The striking thing about this is that there are apparently no obvious adaptations to this height compared to its cousins down below. At these elevations, temperatures are higher than a little lower down, since there are fewer clouds and atmosphere to create colder weather, and so temperatures can and have been recorded at 33°C on the surface of the rocks where the spider resides!

The question of how they got there, I can only speculate, but there are numerous spiders who depend on traversing the winds high into the sky in order to get about, with only a line of webbing to keep its journey under control, so it might be the case that the jumping spiders just kept accidentally flying too far every generation or so, getting lost in the mountains and just dealing with it, only to find its child ends up doing the exact same thing a year or so later until they end up stuck up Mount Everest for eternity.

Jumping spiders are badass. If you don't believe me, check out this whole article I wrote about them some months ago.

Spiders win?

You might think that given the Himalayan jumping spider is the highest known animal to permanently set up shop, that there wouldn't be much else to talk about. But where's the challenge in that? We are indeed only just beginning!

Take a look up at the sky, beyond the lost, floating arachnids and see what you can see. Answers will come next time!

Images sources CC0 licensed

References:

_{BBC Altitude hike | Red Panda | Bailey's Snake | The yak genome and adaptation to life at high altitude | Flight of the bumblebee: 'extreme flight performance of alpine bumble-bees' | Himalayan Jumping Spider}