τὸ κῆτος – a sea monster, a whale
πολλὰ φοβερὰ κήτη ὑπῆρχεν παρὰ τοῖς παλαιοῖς· γνωστὸς δὲ ὁ λόγος περὶ Ιωνα τοῦ προφήτου ὃν κατέπιε κῆτος μέγα·
„Καὶ προσέταξεν κύριος κήτει μεγάλῳ καταπιεῖν τὸν Ιωναν· καὶ ἦν Ιωνας ἐν τῇ κοιλίᾳ τοῦ κήτους τρεῖς ἡμέρας καὶ τρεῖς νύκτας. Καὶ προσηύξατο Ιωνας πρὸς κύριον τὸν θεὸν αὐτοῦ ἐκ τῆς κοιλίας τοῦ κήτους […] καὶ προσετάγη (ὁ θεὸς) τῷ κήτει, καὶ ἐξέβαλεν τὸν Ιωναν ἐπὶ τὴν ξηράν.“
There existed many sea monsters in antiquity: Famous is the story of Jonah the prophet whom a whale/sea monster gulped down:
„And the Lord appointed a great fish to swallow up Jonah. And Jonah was in the belly of the fish three days and three nights. Then Jonah prayed to the Lord his God from the belly of the fish, […] And the Lord spoke to the fish, and it vomited Jonah out upon the dry land.“