Answer:
I thinks it's because since the water washed away all the land, the fish that was living in the water would be washed on land, and all the land animals might be either washed away along with the wave, or drowned due to not knowing how to swim or can't get out of the water in time when submerged underwater, causing almost all creatures living there to die out!
Birth rate, As we grow we might have to cut down on birth
William Smith and Georges Cuvier
