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Nelson, J.S., 1994

Gymnotiformes knifefishes

Actinopterygii

Siluriformes 150 M years

Carroll, R., 1988  |  Colbert, E. and M. Morales, 1991

late Miocene

ສັດທະເລ

ຄວາມສົດ

ນ້ຳກ່ອຍ

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.

Greek aktis = ray, thunderbolt, beam + Greek pterygion, diminutive of pteryx = wing, fin. Ref. 45335.

Greek, gymnos = naked + Latin, forma = shape (Ref. 45335); ous or otos refers to opercle.

( n = 6 ) -
Apteronotidae Gymnotidae Hypopomidae Rhamphichthyidae Sternopygidae

Ref.
[ e.g. 9948]                       

Glossary
                    [ e.g. cephalopods]