| Image of: Gyraulus Image of: Gyraulus
 
 ADW: 062.rjb1.jpg
 
 
 Caption
 Gyraulus
 .The
 Planorbidae
 is a freshwater snail family of the subclass
 Pulmonata
 .  These snails, although aquatic, are lung breathers.  Gills are lacking; instead there is a large pulmonary sac for gaseous exchange.  In the snail shown here, nearly half of the last whorl is occupied by the lung, clearly visible as an air-filled space.  The
 Planorbidae
 |