genesis chapter 1 verse 1 answers your question .It says: In the beginning god created the heavens and the earth.
verse 21 says: and god proceeded to create the great see monsters and every living soul that moves about and the waters swarmed forth according to their kinds and every winged flying creature according to its kind and god got to see that it was good.
you can read this for yourself in your own bible.
Or not. There are animals in the ocean for the same reason there are animals on land. Life evolving by natural selection to fit the environment, be it ocean or land. The bible is not a useful source of information regarding this question.