On the fifth day of Creation God started with the creation of living creature in the water and in the sky. The sea monsters, ‘הַתַּנִּינִם הַגְּדֹלִים’, were refered by name and that signified great energy and power over their domain, the sea. God neutralized the male leviathan, by removing his female and what’s left is the negative aspect, which is the ‘monsters’ of the sea.
“דַּבֵּר וְאָמַרְתָּ כֹּה-אָמַר אֲדֹנָי יְהוִה, הִנְנִי עָלֶיךָ פַּרְעֹה מֶלֶךְ-מִצְרַיִם, הַתַּנִּים הַגָּדוֹל, הָרֹבֵץ בְּתוֹךְ יְאֹרָיו: אֲשֶׁר אָמַר לִי יְאֹרִי, וַאֲנִי עֲשִׂיתִנִי”
“”Speak and say, ‘Thus says YHVH GOD, “Behold, I am against you, Pharaoh king of Egypt, The great monster that lies in the midst of his rivers, That has said, ‘My Nile is mine, and I myself have made it.’”
The Nile river was the source of life for all Egypt. Pharaoh was the Egyptians ‘god’ on earth and it is obvious that he would claim control over the ‘monster’ of his Nile river from where he drew great powers.
God took these powers away from Pharaoh and the Egyptians during the process of the 10 plagues and the splitting of the Red Sea.
“אַתָּה פוֹרַרְתָּ בְעָזְּךָ יָם; שִׁבַּרְתָּ רָאשֵׁי תַנִּינִים, עַל-הַמָּיִם”
“You divided the sea by Your strength; You broke the heads of the sea monsters in the waters.”