The guyver was based around a "bio suited armor" which was contained in box with things which looked like worms around an old film reel, the worm things moved too.
once it graphted on to its host, namely Sho they would have the bug inside of them and would be able to activate it at will.
When you see the intro (if you dont watch the anime) you'll see that he has two unsual prongs (maybe) that move like insect raidars that behave as ears I think (don't really remeber) They could move backwards and forwards on his head. concluding that His bio suit was also possibly some sort of animal ish suit..
But the cartoon is a must.
The guyver unlike many of the other films I've seen portraying man/animal hybrids, dosen'f use it in a sexual way. i.e. Minatours and other half man/animal mixtures are used to show sexuality/ ferilatiy..
however the guyver uses it to described them as losing a concience/soul when they change, they are left as feroscious beasts.