The sounds which Gastrodon make have given rise to the terms for stomach and tooth in many European languages. This is because they possess the ability to swallow even large prey whole, but do not have any corrosive venom such as Arbok or Swalot, so they were thought to possess teeth in their stomach. Legends were told of Gastrodon growing to enormous sizes and swallowing men who escaped through their necks before they were pulled, slowly but surely, to the terrifying, enormous teeth in these pokemon's stomachs.

Because of this tale, warriors often wore helmets into battle patterned after a Gastrodon's horns and fake eyes on their foreheads to terrify their enemies. At times the helmets worked as intended, causing armies to break and flee in fear. At others it worked too well; resisting armies would fight to the death for fear of being eaten, for they were convinced the helmets marked the Gastrodon units as cannibals!

In reality, even the European Gastrodon can not grow large enough to eat human children, let alone full-grown men, and they feed on much smaller tidal pokemon, such as Froakie. But legends can grip the imaginations and terrors of men, and a story told a thousand times can make the most gentle of pokemon terrifying. It is true that Gastrodon possessed large, spiked shells in antiquity, but the spikes were to ward off predators; there is no archaeological or behavioral evidence that they were ever a weapon.

As a further testament to the power of legend to shape perceptions of a pokemon, Gastrodon are far from feared in other parts of the world. Indeed, in Sinnoh and other locations in Asia, their third eye marks them as a uniquely enlightened pokemon and they give their name to a god of the sea!