G.I. Joe: A Real American Hero - Season 1 - Eps 21: Cobra's Creatures
Mutt, Junkyard, & Ripcord are kidnapped by Cobra, so that the evil scientist, Dr. Lucifer, can test his new invention, High Freq, a device which controls the minds of animals and insects, on Junkyard. Cobra use it to gain control of an army of animals to take over the world, and send Junkyard hunting after Mutt. In exchange for High Freq, Cobra agrees to break Dr. Lucifer's love, Dr. Attilla, out of jail. GI Joe learns of this, and has Scarlett pose as Attilla, but it's obvious to Lucifer she is not Attilla, and Scarlett is captured. Snake-Eyes and Spirit come to the rescue, using Timber and Freedom to sneak into Cobra's jungle castle and rescue Ripcord and Scarlet, and stop High Freq.
About G.I. Joe: A Real American Hero

Title: G.I. Joe: A Real American Hero
First Air Date: 1983-09-12
Last Air Date: 1992-01-20
Status: Ended
Rating: 7.7/10 (from 70 votes)
Language: EN
Seasons: 5
Total Episodes: 139
Network: Syndication
Genres: Animation, Action & Adventure, Kids
Production Companies: Sunbow Productions, DiC Entertainment
Synopsis
G.I. Joe: A Real American Hero is a half-hour American animated television series based on the successful toyline from Hasbro and the comic book series from Marvel Comics. The cartoon had its beginnings with two five-part mini-series in 1983 and 1984, then became a regular series that ran in syndication from 1985 to 1986. Ron Friedman created the G.I. Joe animated series for television, and wrote all four miniseries. The fourth mini-series was intended to be a feature film, but due to production difficulties was released as a television mini-series.
Cast

Ted Harrison
Duke (voice)

Christopher Collins
Cobra Commander (voice)

Maurice LaMarche
Destro (voice)

Don Brown
Sub-Zero (voice)

Garry Chalk
Pathfinder (voice)

Morgan Lofting
Baroness (voice)

Suzanne Errett-Balcom
Lady Jane (voice)