which was rather unique for what is at its heart a simple monster movie.
As for inspiration, Giger et al had to look no farther than mother nature: the
http://en.wikipedia.org/wiki/Moray_eel">moray for the mouth within a mouth and the
http://en.wikipedia.org/wiki/Spider_wasp">spider wasp for the use of a host animal in which to grow its embryos.
Ichneumon wasps, with their habit of paralysing but not killing their victim, before laying an egg in it with the promise of a larva gnawing it hollow from within, and the cruelty of nature generally, were major preoccupations of Victorian theodicy. It's easy to see why. The female wasps lay their eggs in live insect prey, such as caterpillars, but not before carefully seeking out with their sting each nerve ganglion in turn, in such a way that the prey is paralysed, but still stays alive. It must be kept alive to provide fresh meat for the growing wasp larva feeding inside. And the larva, for its part, takes care to eat the internal organs in a judicious order. It begins by taking out the fat bodies and digestive organs, leaving the vital heart and nervous system till last - they are necessary, you see, to keep the caterpillar alive. As Darwin so poignantly wondered, what kind of beneficent designer would have dreamed that up? I don't know whether caterpillars can feel pain. I devoutly hope not. But what I do know is that natural selection would in any case take no steps to dull their pain, if the job could be accomplished more economically by simply paralysing their movements.
Richard Dawkins, The Greatest Show on Earth