What does Genesis 1:20 mean?
Verses 20 through 23 describe God's fifth day of creation, in which He creates all the creatures of the seas, as well as the birds. This is according to the pattern of Genesis, where God used the first three days to prepare an environment, and the second three days to populate that environment. On day one God created light, and on day four He created the sun, moon, and stars. On day two God created the sea and sky, and here, on day five, is His creation of sea and air life.The pattern will then continue in later verses: On day three, God created dry land, and we will see the origin of land animals on day six.
God's spoken command is to let the waters—the seas—teem or swarm with swarms of living creatures. The picture is of filling up an ocean intended to carry the abundance of God's creation. In a similar way, God commands the sky to be full of birds that would fly across its previously empty expanse. This is all part of a process where God's design comes into focus. He didn't merely create the oceans for their own sake. The purpose of the seas was to support active, teeming life. The purpose of the empty sky was to host the countless variety of birds He would create.
Genesis 1:14–25 describes the second three days of creation: days four, five, and six, just prior to the creation of human kind. As with the first three, there is a common pattern. God's spoken word results in creation, which God then names and declares ''good.'' The day is then numbered. Each of these days fills something created in one of the prior three days. The sun and moon are created on day four, while day and night were created on day one. Sea creatures are created on day five, for the oceans formed on day two. Land animals—and, later, human beings—are made on day six, for the dry land and plants which God created on day three.
Genesis 1 is nothing less than a bare-bones claim that God created the universe. Setting all of the debates on models and interpretations aside, the chapter undeniably insists on one thing: God means to be known as the Creator of all things. Written in the original Hebrew language according to a rigid, poetic structure, the chapter unfolds in a series of patterns and revelations. For those who believe these words, our response should be nothing less than to worship our Maker.