Sources : Ezochius maris

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Fish 7.37): Ezochius is also that fish of the sea, which is commonly called 'esui'. Here it rises to about seventy cubits in length, and fourteen cubits in height or breadth. In the lower jaw there are two bones like beams; in these there are forty-two large teeth; but in the upper mandible there are no teeth, but in the bones of the upper mandible there are certain cavities to the number of teeth, in which the teeth of the lower mandible, when they touch the upper one, are closed in the manner of sheathes. In the front nature has given it an eye four cubits wide. It has such a wide mouth that a boat that holds twelve men can be enclosed in it. It has intestines in such abundance that they exceed the quantity of intestines in forty oxen. It is an animal of singular thickness. It is captured in this way: it goes out of the sea to fresh waters. When the fishermen have noticed it, they pursue it with crossbows and bows. And when, fleeing, it comes to such straits of water, that it could neither ascend nor return, on account of the importunity of those who follow, it draws up water like the abyss of Scillia, and unexpectedly overwhelms its adversaries with such an inundation, that it drowns most of them as if enveloped in waves. When this attempt is frustrated, it tries something else. It puts his tail to his head and strikes those who approach it so violently that hardly anyone it touches escapes without danger of death. After this, however, if it is captured and defeated, where it has received a fatal wound, it utters a voice of shrieking so horrible that one of the demons seems to have cried out louder than all the sound of beasts or men. - [Badke translation/paraphrase]