I'm attempting to design a creature whose internal anatomy includes a powerful electromagnet so that it can do things like pulling guns out of people's hands at close range.
Like many electromagnets, this electromagnet will be a wire wound into a helical coil - a solenoid. However, this creature must biologically grow the wire itself, rather than have an artificial one implanted into it. As such, I need a biologically-grown electrical conductor.
I initially chose salt water, but, after seeing the electrical conductivity and resistivity of various materials, as well as a list of biometals, I chose calcium, which, at 20° Celsius, has a resistance of 3.36 × 10-8 (0.0000000336) ohm-meters and a conductivity of 2.98 × 107 (29,800,000) siemens; in comparison, annealed copper - a common electrical conductor - has a resistance of 1.72 × 10-8 (0.0000000172) ohm-meters and a conductivity of 5.8 × 107 (58,000,000) siemens at 20° Celsius. That's ~1.95 times less resistant and ~1.95 times more conductive than calcium.
While calcium isn't quite as good a conductor as copper (annealed or otherwise), it's much more readily available to an organism with Earthly biology. That, along with calcium's within-the-ballpark-of-copper performance as a conductor, made me decide to use a strand of calcium as the wire of this creature's electromagnet.
There are several caveats to this:
- as far as I know, only pure calcium metal embodies these characteristics, and compounds of calcium don't
- calcium metal "reacts exothermically with water and acids", and internal exothermic reactions aren't good for any creature
- in addition to that, this wire will be carrying serious current (at least 2,000 amperes)
- on top of that, calcium tends to be highly reactive, meaning that it likes doing chemistry with things
- finally, since this biological calcium wire will be carrying a lot of current, it'll put out a lot of heat
As such, I - for the sake of insulating this calcium wire - require a calcium compound that is:
made out of calcium and (an)other material(s) that can be easily metabolized by a creature with biology similar to Earthly life; no xenon, uranium, arsenic, or such, please
resists electricity and heat as much as possible
conducts electricity and heat as little as possible
This way, the compound in question stops the calcium wire from reacting with, electrocuting, or burning the rest of the body.