Was Leviathan a unique individual or a species?

Job 41:

1 Can you draw out Leviathan with a fishhook or press down his tongue with a cord?

ESV note:

A large sea animal, exact identity unknown

The Hebrew word livyātān (לִוְיָתָן) was singular, and the passages that mention Leviathan consistently speak of it as one identifiable being. It was not described as a species. It was presented as a specific, singular creature, though its exact nature is debated. The LXX translated it as δράκοντα, meaning 'dragon'.

Ps 74:

14 You crushed the heads of Leviathan; you gave him as food for the creatures of the wilderness.

Leviathan was depicted as having more than one head in this poetic and theological context. It was likely to be a unique creature.

The Jewish Encyclopedia:

According to a midrash, the Leviathan was created on the fifth day. Originally God produced a male and a female leviathan, but lest in multiplying the species should destroy the world, He slew the female.

Ps 104:

25 Here is the sea, vast and wide, teeming with creatures beyond number, living things both great and small. 26 There the ships pass, and Leviathan, which You formed to frolic there.

The noun was singular.

Is 27:

1 In that day the LORD with his hard and great and strong sword will punish Leviathan the fleeing serpent, Leviathan the twisting serpent, and he will slay the dragon that is in the sea.

Isaiah pronounced Leviathan as a special creature.

Rv 12:

9 The great dragon was hurled down—that ancient serpent called the devil and Satan, the deceiver of the whole world. He was hurled to the earth, and his angels with him.

Some think Leviathan symbolizes Satan.

Discover the fierce predator, Livyatan melvillei,

Scientists named a prehistoric sperm whale 12 million years ago *Livyatan melvillei.