Actually, we’d have to retro-evolve back to webbed feet and gills like the mermen/mermaids shown on the Animal Planet series.
That was one of the all-time great spoofs, right up there with Orson W's radio version of "War of the Worlds", during the hour or so of which Martians are supposed to have landed, fought the army, killed some soldiers, and during a return to a program of dance music (lasted a few minutes) one of the dead soldiers' body was driven some miles away and autopsied and the report was ready. :')