Zigra invaded earth with the intention of enslaving the human race and raising them like cattle - he came from a planet where instead of people eating fish, fish eat people (thus making the film the first known Japanese instance of the Russian reversal). Like Viras attempted three films earlier, Zigra held a pair of human children hostage in order to force the human race to conform to his plan, but Gamera engaged him in battle. Gamera eventually threw him on land, using a rock to play his theme song on Zigra's dorsal fins like a xylophone before burning the huge Alien shark alive, incincerating and killing Zigra.
Zigra's attacks are all based around his blades on his back, head and, fins. His great speed and agility allows him to easily doge Gameras attacks and out monover him. But Zigra's weakness is that he is helpless outside of water. Zigra can also shoot a beam of light from the gem between his nose that paralayses an opponent.
Like many of his fellow Showa monsters, Zigra has not made a film appearance outside his initial debut, (except for the obvious stock footage scenes). However, he made an appearance in the Gamera comic series by Dark Horse Comics, that was based on the Heisei Gamera series. In the story, Zigra was an escaped alien creature from outer space, who managed to find his way onto Earth. He'd eventually meet up and face Gamera, who made relatively short work of him. In this series, he was pretty much unchanged, except for the fact he was more of a wild animal, and was more aquatic-based.