#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 of:  fish
  part:  ray.spine  any of the stiff bony rods in the fin of a fish

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