Question: "Why did God also destroy animals in the Flood (Genesis 6-8)?"
Answer: God sent the Flood as a judgment on mankind’s wickedness. But it wasn’t only human beings who died. Most of the animals were also swept away. Genesis 6:7 states, “I will blot out man whom I have created from the face of the land, man and animals and creeping things and birds of the heavens, for I am sorry that I have made them.” Why did God destroy animal life in the Flood, since they were not guilty of sin?
First, it should be noted that God did not destroy all animal life. Two of every kind of unclean animal were placed on the ark, and seven of every clean animal (Genesis 7:1-4). In addition, sea life was not harmed. The destruction included land animals and birds.
God had a plan to recreate. Just as God had created human and animal life in the beginning of time, so now He would recreate human and animal life. Genesis 8 closes with the animals leaving the ark at the beginning a new world. They went with the command to go forth and multiply (Genesis 8:17).
We can assume that, in some way, animal life had become corrupted along with human life. Genesis 6:13 states, “I have determined to make an end of all flesh, for the earth is filled with violence through them.” The phrase “all flesh” is used throughout the narrative to include both human and animal life. How was animal life corrupted? This is not explained. Some have suggested the use of animals in sinful, pagan sacrifices as the reason. Others have considered that the violence filling the earth was due, in part, to animals (this would correspond with the theory of large dinosaurs being destroyed by the Flood). Regardless of how the animals became corrupted, God viewed them as part of creation that needed to be recreated.
Another concern was Noah’s welfare. Perhaps the land animals were destroyed so that Noah and his family could live safely after exiting the ark. Eight humans living in a world of unchecked wildlife would have had a slim chance of survival, most likely. But with only the animals on the ark, the ratio of animal life to human life would make living together much safer. God could have chosen a different method, but He chose to save Noah and his family, along with a large boat of animals, to restart life on earth.
Elsewhere in the Old Testament, we see that a person’s sin can contaminate other people or animals at times (e.g., Joshua 7:24-25; Romans 8:19-22). In a ceremonial sense, perhaps, the animals that died in the Flood could be viewed as morally contaminated because of their association with humankind. They were part of that antediluvian, sin-infested world.
In summary, God destroyed many animals in the Flood, but not all of them. In fact, He spared many more animals than He did humans. God chose to recreate using a limited number of animals, sparing only those land animals that He led to the ark. After the Flood, God provided for a safe coexistence between human and animal life.