For most of history, sea monsters were considered among the greatest perils of sea travel. Most probably, the “monsters” that they feared were simply whales, sharks and giant squid that have now been thoroughly researched by modern science and are no longer considered “sea monsters.” However, the Midrash (Jewish legend) does record the existence of one “sea monster,” the mighty Leviathan.
On the fifth day of creation, the Torah states in Genesis 1:21, “Va’yivra Eh’loh’him et ha’taneeneem ha’g’doleem,” “God created the giant sea creatures.” The meaning of taneeneem has been much debated (sea monster, whale, crocodile, etc.). In the Talmud, Rabbi Yochanan said (Baba Batra 74b): “This refers to Leviathan the flying serpent [male] and to Leviathan the twisted serpent [female], for it is written: ‘In that day God . . . will punish Leviathan the flying serpent, and Leviathan the twisted serpent; and He will slay the dragon that is in the sea’ (Isaiah 27:2).”
So why have scientists not found Leviathan? According to the Midrash, only a single Leviathan still exists: “Rabbi Judah said in the name of Rav: All that the Holy One, blessed be He, created in his world he created male and female . . . and had [the male and female Leviathan] mated with one another they would have destroyed the entire world. . . . What did the Holy One, blessed be He, do? He castrated the male and killed the female, preserving it in salt for the righteous [to eat] in the world to come . . .” (Baba Batra 74b). Additionally, Rabbi Yochanan points out that God “will, in the ‘time to come,’ make a tabernacle for the righteous from the skin of Leviathan” (Baba Batra 75a).
There are numerous other places in rabbinic literature where Leviathan is mentioned and described as enormous, multi-headed, fire-breathing . . . apparently Leviathan is the original sea monster.