When the two Gappa creatures are attacking the industrial part of Tokyo towards the latter end of Gappa-The Triphibian monster, one of them rears back its head and roars. That brief excerpt ended up being used in the Red Dwarf 4th season episode Meltdown, on a planet that featured some fake-looking dinosaurs.
OK, so much for where I first saw these beasties. But what is a Gappa? Well, if Godzilla and Rodan mated and had a baby, it'd probably look like Gappa. It's inherited Rodan's head and wings, and Godzilla's gray-green scaled body, blue flame, and a resonant roar more like the sound of a flushing toilet played backwards, it doesn't give a rapid constipated bark like Rodan, but durned if I know whose eyes it got.
The story too is derivative, coming from Mothra. Basically, Mr. Funatsu, publisher of Playmate Magazine, finances and sends a team that includes reporter Kurosaki, female photographer Koyanagi, and scientist Tonaka to Obelisk Island in the Pacific to collect bird and animal specimens, as well as native women. His plan is to open a holiday theme park so that Japanese do not have to go all the way to the Pacific to get that exotic Polynesian atmosphere. The expedition is greeted by the dark-skinned islanders, led by a white-haired patriarch (same as in Mothra). However, despite warnings from the young boy Saki not to enter a cave, Kurosaki and Koyanagi do so and find an egg which hatches into a prehistoric-looking reptile. The expedition take it back with them to Japan, against the wishes of the natives. "Gappa angry," they keep repeating. And that's true, as the parents of the abducted baby head over to Japan to recover their child (q.v. Mothra coming to Japan to rescue the twin fairies). But Funatsu's profit-motivated greed gets the better of him, like Nelson in Mothra, and he refuses to give the baby up, even despite the pleading of his young daughter.
The scenes of destruction are nothing much to shout home about, as they are the usual retreads of people in rubber suits stomping on model Tokyos, trampling on buildings, melting model tanks, blasting airplanes out of the sky, and convoys of military vehicles.
Apart from this being widescreen and in original Japanese, something not available in any of the Toho monster pics over here, there are some interesting issues explored. One is the examination of empathic understanding. In one scene, Saki and Funatsu's young daughter go up to the captured baby, who quiets down and looks at them sadly, showing a link between animal and human kindness.
Another is the role of women in 1960's Japan. In the dark cave, Koyanagi becomes a bit hesitant. Kurosaki then taunts her, "[fine], go back marry an office worker, have babies and change diapers" a la the traditional role of women in the modern world. One phrase that isn't translated in the subtitles is "tamanegi o kitte," meaning cutting onions. In other words, stay in the kitchen.
So what does that title mean, "triphibian"? Well, given its Greek etymology, amphibian means able to live a double life, in water and in land, as frogs and salamanders. Triphibian thus means water, land, and air.
Despite some serious issues explored, material cribbed from Godzilla, Rodan, and Mothra by Kaiju Productions, (kaiju meaning Japanese for monster) and unconvincing monsters overshadow what could've been a good story.