The biological truth Wells has given us would slow down an alien encounters on Star Trek or Farscape, where intrepid adventurers rarely worry about local languages, much less breathing the local air. The aliens have invaded because they have a fondness for human blood, sucked from living beings (how they discovered they had a taste for us is unclear, but it makes dramatic theater, anyway). If you haven't read Wells, you need to; Wells created a landmark -- he is a thoughtful social commentator, a pioneer of what makes SF intellectually appealing, and a damned fine storyteller, too.
Herbert George Wells (1866 - 1946)-known as H. G. Wells-was a prolific English writer in many genres, including the novel, history, politics and social commentary, as well as textbooks and rules for war games. Wells is now best remembered for his science fiction novels and is called the father of science fiction, along with Jules Verne and Hugo Gernsback. His most notable science fiction works include The Time Machine (1895), The Island of Doctor Moreau (1896), The Invisible Man (1897) and The War of the Worlds (1898). He was nominated for the Nobel Prize in Literature four times.