One of the curious features of Spider-Man as a creative property is that it has long practiced a form of "facial erasure" that, to varying degrees, denies the geometry of the human head. The degree of indulgence varies from artist to artist; nearly all deny the existence of the nose to a degree that makes anime seem anatomical by comparison, but skim through panels rendered for the comic and you'll often spy depictions that gloss over the ears and chin as well. From this cutting of corners, one can only conclude that the logical conclusion of the Spider-Man brand is a sort of Spider-Egg, with the entire franchise following a slow Benjamin Button arc of the character gradually morphing to his pre-hatched state.
Spiders don't even have heads. Spider-man is only approximating that.