Assertion: dolphin's flipper | /r/ObjectUse | used for steering
Facets:
value: mainly
type: DEGREE
Source sentences:
text: Dolphins swim by moving their tail fin and rear body vertically, while their flippers are mainly used for steering.
text: River dolphins swim by moving their tail fins and lower bodies up and down, propelling themselves through vertical movement, while their flippers are mainly used for steering.