Assertion: beaver's head | /r/HasProperty | visible
Facets:
value: unlike a muskrat
type: OTHER
value: usually
type: DEGREE
Source sentences:
text: When swimming at the surface, only the head is usually visible, unlike a muskrat where both the head and back are partly above the water.  
text: When swimming, only a beaver's head is visible.
text: When swimming, only a beaver's head is visible.