It's possible that the first alien from space encountered by humans will be neither a bug-eyed green dude or a dead ringer for Mr. Spock. Our own planet provides the clues: creatures on the bottom of the sea do not move and communicate the way us land-based bipeds do.
The conditions on the home planet for any species would likewise dictate what they look and move like. Zoologist Arik Kershenbaum at the University of Cambridge explores this thinking in the book The Zoologist's Guide to the Galaxy: What Animals on Earth Reveal About Aliens–and Ourselves.
Prepare for a chat pushing the boundaries of how we think about other animals--and humans.