The seventh installment of the Showa-era '''{{Gamera}}''' films. Earth is invaded by inhabitants of the planet Zigra, a water breathing race that wants to use humankind as a food source. Its up to Gamera and a handful of children in the thick of it to save the day. Daiei Studios filed for bankruptcy shortly after the release of this film, leading to a nine year hiatus until the eighth and final Showa Gamera film would be released.

This is one of nine films to be used twice on ''Series/MysteryScienceTheater3000'' once on the local Minneapolis UHF station KTMA in 1988 during the local run of the show and later when running nationally on ComedyCentral. For those versions please go to the [[Recap/MysteryScienceTheater3000S03E16GameraVsZigra episode recap page]].

!!This film provides examples of:
* AbsurdlySharpBlade / SpikesOfVillainy: Zigra
* AlienInvasion: The planet Zigra wants to take over Earth to use humans for food.
* ArtisticLicensePhysics: Gamera breaths fire '''underwater'''.
* BlatantLies: Lora Lee chases the children with the clear intent to kill them, all the while shouting, "Come back! I won't hurt you!"
* BrainwashedAndCrazy: [[spoiler:Zigra's henchwoman Lora Lee]], as it turns out.
* DisneyDeath: Gamera gets one, [[OnceAnEpisode naturally]]; but also [[spoiler:the crew of the bathysphere]].
* DubInducedPlotHole: The Sandy Frank Dub places the film taking place in [[TheEighties 1985]], despite the fact that the film was originally released in [[TheSeventies 1971]].
* EverythingIsAnInstrument: [[spoiler:Even Zigra's beached corpse]]
* [[ThreateningShark Everything's Even Worse With Sharks]]: The aquatic aliens from planet Zigra resemble sharks.
* FlyingSaucer
* GreenAesop[=/=]FantasticAesop: Don't pollute the oceans, or Space Sharks will come down and eat us all!
* HumiliationConga: [[spoiler:In between being defeated and being roasted to death, Zigra gets ''played like a musical instrument.'']]
* KillItWithFire
* LightningCanDoAnything: including [[spoiler:revive a giant turtle]]
* MissingMom: Helen's mom is said to be in a New York hospital.
* MsFanservice: Lora spends a few minutes in a skimpy two-piece bikini, and the rest of the movie in a T-shirt and skirt.
* NamesTheSame: The monster Zigra comes from the planet Zigra.
* NameThatTune: Gamera plays his own theme music, using Zigra's fins as a xylophone.
* ParentService: The Zigra minion Lora Lee is introduced wearing form fitting SpaceClothes before switching to a bikini in an attempt to blend in with humans, finally settling on a mini skirt for the remainder of the film.