Leviathans

Leviathans (原生海獣クジラ ,) are primordial sea beasts which inhabit the deep waters surrounding the continent. The Leviathans are the reason humanity has not ventured beyond the Continent. They are territorial creatures, zealous in defending the waters and skies in the vicinity they live in. They are able to swiftly dispatch water and air craft using the laser-shooting organ on their forehead.

Trivia

 * The original Japanese name for the creature is Kujira, meaning 'Whale', while the kanji translates to 'Primordial Marine Mammal'. The translator decided to render it as 'Leviathan' due to its double meaning as both whale and sea serpent in Hebrew.