Maybe this kid is really ugly. Maybe he was born without a nose or mouth. Maybe his skin is inside out on all parts of his body other than his arms and upper face. Maybe he fell down just as this picture was being taken. Maybe the photographer fell just as this picture was being taken. Maybe... ok, I've run out of possible reasons for showing nothing but the kid's upper head and arms.
Maybe Daniel isn't talking because you didn't think his mouth was important to the cover of the book.