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I have a concept for a species of arctic-dwelling organism (let’s just call it a polar bear) that evolved an organ that was able to produce microwaves, which it uses to tunnel through ice.

If such a thing is possible, my question is: which already-existing organ(s) would evolve into this new organ (like how electrocytes evolved from muscle cells in electric eels), what organic structures and processes would develop inside this organ, and what ramifications would this have on the organism’s physiology? As in, how would its body change in order to cope with this new organ?

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  • $\begingroup$ This is a very subjective question and I'm voting to close as POB. Given enough time, pretty much anything can evolve into anything. Biology already uses electricity, so hind sight makes it logical that a muscle might evolve into an electrocyte. But nothing about biology (that I know of) uses microwaves, which makes this a complete guess, which is off-topic. Further, asking 4 questions is too broad (also a reason to close). If you ask one, specific question and qualify the question so there can be a best answer, I'd be happy to retract. $\endgroup$ – JBH Aug 17 at 18:55
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    $\begingroup$ At the time of this comment, the two answers don't seem to have addressed the concern that microwaves, whilst good at heating liquid water - ice is really quite unresponsive to microwave energy. Unless you've compelling reasons to write this into your story (for which you would need to concoct an elaborate scenario involving squirting hot water onto the ice to melt it), you might want to go with infra-red as more practical. $\endgroup$ – 011358 smell Aug 17 at 20:20
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    $\begingroup$ I think it is a bad practice to radically reformulate a question after people start answering it. It creates a discontinuity where the efforts of people providing answers look misguided since they answered an old question. It is a better practice, and more respectful of contributors efforts, to create a new question. As it stands now, everyone that provided answers looks like rather foolish since you changed the topic of your question. $\endgroup$ – EDL Aug 18 at 6:28
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    $\begingroup$ I'd almost consider this XKCD What-if to be an answer. From an energy perspective, melting ice is very expensive for an animal. $\endgroup$ – Cort Ammon Aug 18 at 6:28
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    $\begingroup$ Dude, no. Don't completely change the subject of your question after answers have been supplied. Submit a new question instead. $\endgroup$ – Starfish Prime Aug 18 at 9:42
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TL;DR: generation of high power microwaves from organic mechanisms is very, very hard and evolutionarily unlikely. Microwaves are also a terrible way of tunnelling through ice. Note that polar bears and leopard seals don't bother in the real world; who are you to argue with those highly effective apex predators?


As another answer already touches on the inefficiency of melting ice (even more so when you consider that there's no energy-dense food in there to make the tunnelling worthwhile!) I won't go into that, but lets consider the physiological issues of microwave generation.

Microwave generators have two important kinds of material that are hard to come by in nature: microwave-transparent materials, to cover and protect the business end of the emitting device, and microwave-reflecting materials to ensure that all the microwaves go where they are wanted (eg. out the front) and aren't absorbed by the rest of the equipment which would cause undesirable power loss, heating and damage.

Lightweight polymers like polystyrene or polythene are easy to come by courtesy of modern chemistry and industry, but there aren't many good biological equivalents. The presence of any water is undesirable (because of the resulting energy loss, heat generation and ultimately physical damage that will result) and growing a water-free biological membrane sounds like an absolute nightmare, and something deeply unlikely to evolve naturally. It is remotely possible that you could have some sort of super-thin layer of specialised bone, horn, hair or tooth and have the extruding layer of cells die off, maybe.

Similarly, sheet metals and metal meshes have been available to humans for millenia, but bulk deposition of metals in organic creatures isn't a thing, let alone formation of nice smooth reflecting cavities. There's no obvious evolutionary path to such a trait... seems like mineral/protein composites that most tooth or bone or shell-bearing animals produce is quite good enough without the hassle and energetic expense of refining metals.

Finally, even if you've solved those two not-insignificant problems, you need to actually generate microwaves. Human approaches to this involve vacuum tubes (good luck evolving a vacuum-sealed cavity in a biological organism!) or semiconductors. The latter might just possibly be able to have some organic counterparts but: they are low power microwave sources, the sort useful for communication, perhaps, but not for generating the enormous amounts of power you need to melt enough ice to fit your body through.

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While it's imaginable that an organ could evolve to emit low-powered microwaves, this is not a practical way of tunnelling through ice.

Melting ice - changing it from solid to liquid without substantially altering its temperature - takes a lot of energy. According to Wikipedia, enough energy to raise the temperature of an equal mass of water by 80°C. You then need to raise the temperature of the newly melted water enough to let it flow away before the heat leaks away into the surrounding ice and it freezes again.

Your creature needs to radiate all of that energy as microwaves without cooking itself, which is not plausible, supply rather more chemical energy to the microwave generator organ, which is not going to be 100% efficient, and eat enough to supply all that chemical energy as well as its normal needs. It's just not evolutionarily plausible. Evolving strong claws or teeth, and the muscles to use them to tunnel through ice is far more practical.

The question has now been changed to infra-red emissions, rather than microwaves. This gives more effective use of the radiated energy, but as I failed to consider the ineffectiveness of microwaves in melting ice, simply makes my answer less over-optimistic. Tunneling via infra-red radiation is still completely impractical from an energy point of view.

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  • $\begingroup$ Tunneling through sea ice or glacial ice is basically impractical no matter what means you use. There aren't a whole lot of creatures that bore through solid rock, for example, and you're less likely to freeze to death doing that. $\endgroup$ – Starfish Prime Aug 17 at 19:38
  • $\begingroup$ @starfishprime solid rock is usually at least 5.5 to 6 times denser than ice. Polar bears do dig into ice to build their dens. $\endgroup$ – Renan Aug 17 at 19:56
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    $\begingroup$ @Renan they dig into dense snow, not ice. Ice is too hard for polar bears to tunnel into, and is a much more effective material for losing body heat into. $\endgroup$ – Starfish Prime Aug 17 at 20:01
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I agree with all the observations that such an organ would be as unlikely to evolve as Douglas Adam’s Babel Fish. But, if it did it would more than likely have these properties

  1. A primary dimension — longest — an integer multiple of 6.25 cm. This would allow the cavity to resonate at the same frequency as a microwave oven ~2.3 GHz — the resonant frequency of hydrogen

  2. The organ would be some sort MASER on the animal's skull or spine or shoulder blades or pelvis. The wavelength of the emission excites hydrogen atoms in molecules and while good for softening the ice, it's bad for organic tissue since it will tend to cause their proteins to cook. I think this means the rest of the bear, or walrus must be protected from the emission. I can’t think of a really good way to do that sort of metal shielding which would be odd. Conceptually a complex series of layered materials could form an interference pattern and act as an RF mirror but doesn’t seem evolutionarily likely

  3. Some sort of chemical reaction similar to a primary cell battery to generate the power needed to drive the organic maser in the bear's skull (or wherever)

The maser wouldn’t melt the ice but since the skin depth of 2.3 GHZ is very long, the maser could soften the ice, causing fractures, that would allow the bear's great physical strength and adamantium claws — sorry, those are wolverines, right not bears — strong and sharp claws to carve the ice.

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You said "tunnel." You didn't say "melt a huge glob of ice that leaves the empty space desired."

Different tactics are required. The critter won't be melting entire tunnels. It will be using something-or-other to cut blocks that it is then able to push out of the tunnel. It is evolving an ice knife, not a subway-tunnel-digger. It's a snow knife such as used by northern dwelling folk to build shelters out of ice.

Not microwaves, not ultraviolet, but ultrasound. The critter would have a specially developed item in its claws that sent out an ultrasound pulse to weaken the ice along a narrow slice. It would do this to weaken a block which it could then tug out using regular old brute physical force. Maybe it has a particular pattern that it starts with from the surface so it can get wedges of ice out and then push them out the tunnel. Maybe it has different frequencies for different types of ice, depending on the amount of trapper air etc.

The amount of ice it actually has to affect is extremely small, perhaps a fraction of a millimeter. In principal it could use a lot less energy doing this than trying to break the blocks out with its claws. The splits would be a lot cleaner with less fractures, so the tunnel would be more stable. The bear could even be clever enough to use the ejected blocks to build some simple structure at the entrance to the tunnel. Even if it's just a simple pile of blocks to disguise the entrance of the tunnel.

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It’s an alien from a planet where all the vertebrate-equivalents have metal bones. In its particular case, it has an organ with a coiled metal bones that can function as a microwave antenna, connected to electocytes that pulse at microwave frequencies. The microwaves that this organ generates are then focused by a metal “bone” dish and projected through a layer of horn onto the things it wants to heat up (e.g. prey animals, most likely).

It evolved this organ from the crude organic radios that animals on this planet developed as a result of nerves being connected to their bones to register the voltage their bones registered while acting as radio antennas, then other animals developing electrocytes that could transmit signals as well as receive them.

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