Question People for parts

Was watching, sort of, Mysteries Decoded last night and it spawned a twisted idea about how my space elf gets stranded on Earth: she was picked up on her homeworld, to be a replacement part for an alien space craft. But the problem with this idea is why wouldn't the aliens remove the relevant bits? Lop off limbs if she's a new power core, remove the brain if she's a computer...
I think I'll likely go back to the slave trafficking idea I had in the first place.

Limbs regrow, and trying to chop them off makes her devote all the power to it.

Things might be different with space elves, but one issue that you get with de-limbing humans is increased fragility. In the context of treating a body as a largely immobile part in a machine, limbs are basically resource reservoirs. They store extra blood, protein, and calories that the rest of the body can cannibalize when needed, making it less sensitive to transient problems. Limbs also contain bones, which are what generate blood cells, so having more limbs means faster regeneration of lost blood and a more robust immune system. Limbs that are free to move also function as self-adjusting heat radiators -- they can be extended away from the body to increase exposed surface area when heat needs to be shed, and held close to the torso when surface area needs to be minimized to increase heat retention.

Depending what you're using the elf for, they might also have relevant organs that are distributed throughout their body. For example, if you're using the elf as a neutrino sensor, you could say that space elves have neutrino-sensitive cells spread through their skin much like how humans have touch-sensitive cells all over. Removing limbs would therefor reduce the elf's effectiveness as a sensor.

One of the big advantages in using living creatures over machines is that most creatures are capable of performing at least some of their own maintenance -- and humanoids can usually perform the bulk of it. De-limbing them severely hampers this, potentially creating a situation where the living creature requires more maintenance from crew than a technological solution would have.

Another factor to consider is that de-limbing a body will reduce your options for what you can do with that body later. Hard to repurpose your warp drive into a maid if you've removed its limbs, and it'll usually be worth less money if you ever try to sell it.

And, assuming that 'Space Elves' ("eeeelllvvveessss iiinnn spaaaaaaccceee!!") are like humans, remember that while we tend to think of the brain as the computer that runs our body-machine, in fact, thought, memory and emotion are distributed throughout our entire nervous systems. A person who loses an arm or leg really IS different afterwards, and it's not just the trauma or the loss of an appendage; they have literally lost a chunk of their minds. So, lopping off one of your lop-eared captives limbs changes who they are, in more ways than one.

I thought you were asking for some spares. If so, I would be more than willing to give you all of mine, except my brain, that's pretty much rotten and useless.

Actually, they all are, but right now getting disassembled and having that nasty lump of gray matter tossed to wolves sounds pretty good right now.

Thanks Kettle, that explanation actually made a few Trek episodes make more sence, beyond Status Quo is God.