'Sea monster' in the Bible

In that day Jehovah with His great and fierce and strong sword shall punish the sea-monster, the darting serpent, the sea-monster, that twisting serpent; and He shall kill the monster in the sea.

Awake! awake! Put on strength, O arm of Jehovah. Awake! as in the days of old, in the generations of old. Was it not You who cut Rahab into pieces, piercing the sea-monster?