Order Summary for Gymnotiformes

  Main Ref
:
  Order
:
Gymnotiformes knifefishes
  Class
:
Actinopterygii
  Sister Order
:
Siluriformes 150 M years
  Ref..
:
  First Fossil Record
:
late Miocene
  Occurs in
:
Marine
Fresh
Brackish
  Remark
:
Body eel-like (compressed or rounded); pelvic girdle and fins absent; dorsal fin absent; anal fin extremely long (more than 140 rays and extending from near pectoral fin origin to near tip of body) and employed in forward and backward movements; caudal fin absent or greatly reduced; restricted gill openings; anal opening under head or pectorals; basal pterygiophores to anal fin with only one section (radial) and a hemispherical cartilaginous head that articulates the fin rays (allowing them to move in a circular motion); electric organs present; suboperculum absent; palatine not ossified; maxilla rudimentary.
  Classetymology
:
Greek aktis = ray, thunderbolt, beam + Greek pterygion, diminutive of pteryx = wing, fin. Ref. 45335.
  Orderetymology
:
Greek, gymnos = naked + Latin, forma = shape (Ref. 45335); ous or otos refers to opercle.
  Families
: