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Isonades can live for over ten millennia and spend most of that time in hibernation. When an isonade is preparing to hibernate, it will consume a huge quantity of food: it can eat anything but prefers big prey like giant squid and whales. An abundance of fish can signal the territory of an isonade who has eaten all the predators. An isonade can hibernate for centuries, waking when its food stores run out or when startled by a natural disaster.1
Because of this long hibernation, isonade rumours are often embellished, making their exact territories hard to predict. When first rousing, an isonade beings with the large, slow prey in the depths, but inevitably circles upward as its appetite grows. Isonades are intelligent enough to know that a ship contains many warm and screaming snacks in one convenient place. Ship captains often take extra crew when moving through an isonade's territory, knowing that some of them might just vanish.1