Assertion: gill | /r/CapableOf | call opercula singular: operculum
Facets:
Source sentences:
text: http://i.imgur.com/rsMJwTM.png?2] Alternate opening of the mouth and two flaps of skin that cover the gills called the opercula (singular: operculum) helps to force water across the gill surface = '''ventilate''' the gas exchange surface.