“living souls.” The Hebrew word translated as “soul” is nephesh (#05315 נֶפֶשׁ), and nephesh has a wide range of meanings. One of those meanings refers to the life force that animates humans, land animals, and many sea creatures. It is the “soul” animating the person or animal that makes the difference between a living person or animal and a dead one. For that reason, nephesh is also used for the “life” of a person, as in, “do not take my life,” i.e., “do not kill me.” Nephesh is also used in the sense of “individual,” both of people and animals. Therefore, it sometimes gets translated as “creature” (CJB; HCSB; ESV; KJV), because the living individuals in the sea were “sea individuals” or sea creatures. It is not well recognized in Christianity that the same life force that animates humans animates animals. In large part that is due to the fact that the word nephesh is not translated as “soul” in most English Bibles when it comes to animals. Here in Genesis 1:20, the animals were given life and became living individuals, living souls. In Genesis 2:7, Adam became a “living soul,” a living individual, just as these animals had earlier.
[For more information on “soul,” see Appendix 7: Usages of “Soul.”]
“across the expanse of the heavens.” The Hebrew is more idiomatic: “upon the face of the expanse of the heavens,” as if the earth observer is looking upward and the heavens are the backdrop to the flying birds.