<P>Did you know that a barn owl has one ear higher than the other? This helps it find squeaking mice that humans can't hear. Baby opossum hang on to their mother's fur for safety. Read and find out more about what nocturnal animals do as we sleep.</p> <P>Outstanding Science Trade Books for Children 2000 -- selected by Natn'l Science Tchrs Assoc. & Child. Bk Cncl.</P>