#fin  organ of locomotion and balance in fishes and some other aquatic animals
  supertype:  extremity__appendage__member  an external body part that projects from the body; "it is important to keep the extremities warm"
  subtype:  dorsal_fin  pectoral_fin  pelvic_fin  caudal_fin
  part:  ray.spine
  part of:  fish  any of various mostly cold-blooded aquatic vertebrates usually having scales and breathing through gills

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