These generals used bomber-like spaceships called Grotectors to create artificial black hole vortexes to travel to Earth and back. Throughout the series the Death Cross Generals and Darius note that natives of Zela originally came to Earth for research purposes before slowly colonizing the planet and using it to hide various dark monsters with the rise of humanity, as far back as one million years before the start of the series until the twelfth century AD. For their military natives of Zela were brainwashed and genetically altered into birdmen called the dark avians with elite individuals becoming dark knights. A mecha defender robot consisting of three separate components: the Great Space Dragon's head, an arm unit, and a leg unit (the arm and leg units are stored inside the Great Space Dragon and exit from a gateway located below the Dragon's head). These three launch from the Great Space Dragon and combine, while in flight, to form Gaiking. The Great Space Dragon's head forms Gaiking's core (i.e., chest and back) and contains Gaiking's own head. Gaiking is operated by baseball star Sanshiro Tsuwabuki ("Aries Astonopolous" in English and "Brando Drummond" in Spanish). A gigantic dragon-shaped robot (known as the Great Space Dragon or Kargosaur in the English version) that defends Earth from invaders from the planet Zela. It possesses numerous weapons and houses the sections of the Gaiking super-duper attack robot. Both Gaiking and the Daiku Maryu are composed of the super alloy Zolmanium Steel which was later reinforced with iron deposits from the Moon. A small tank-like robot resembling a Plesiosaur, Nesser is used for scouting missions in water. Its weaponry includes lasers emitting from its eyes, a flamethrower emitting from its mouth, and three mortar cannons located on its chest. (Known as Dynatar in the English and Super-Caracol in the Spanish versions, respectively.) A small jet-like robot resembling a Pterodactyl, Skylar is used for scouting missions in the air. Its weaponry includes machine guns and missiles. (Known as Skylar in the English and Spanish versions as well.) A small, but very fast, tank-like robot resembling a Triceratops, Bazolar is used for scouting missions on land. Its weaponry includes laser canons, a drill, and a mortar cannon. (Known as Rhinatar in the English and Super-Tanque in the Spanish versions, respectively.)    "Daikū Maryū Gaiking" was Toei Animation's first super robot series not based on an existing manga (the company's previous super robot anime Mazinger Z, Getter Robo, etc. were based on manga series by manga artists and writers Go Nagai and Ken Ishikawa respectively).