Maybe ... What if we are actually seeing genetic constructs by AI or Aliens from another planet?
Because, what if the only way to safely traverse interstellar space is to send fully automated AI ships that will explore for you. Once they get to a planet with life they would reconstruct themselves by manipulating the genetic material found on the worlds they encounter (animal mutilations come to mind) and incubate or printout carbon copies of whoever/whatever they have on their ships' genetic files from the homeworld.
If they find a planet with highly intelligent life they could then begin a program that would genetically splice their alien DNA into the hosts until they have created something that is more like them than the host. They could effectively colonize other solar systems without leaving their home planets.
Imagine it, you're not originally a water world species but you could easily become one through genetic splicing and manipulation. There would be no life spawning habitat you couldn't live on.