Originally Posted by freshstart
I always thought that it was because God cursed the ground when Adam and Eve sinned....He did not curse the sea.
Also, it appears that God DID curse the land animals as well, and not just the serpent:
Gen 3:14 Because you have done this, You are cursed more than all the cattle, and more than every beast of the field.........
The term more than seems to denote a comparative factor, as in God cursed ALL land animals, but the serpent's curse was more severe. It appears as though God destroyed those forms of life on which He placed the original curse.
Anyhow, this was just my impression