There is a reason the world—including the animal kingdom—suffers strife and violence. In Genesis 2 and 3, we see that in the beginning, before sin entered the world, God's creation had been one of total harmony and peace! God offered our first parents a way of life which would lead to every blessing imaginable and, ultimately, to eternal life.
However, they rejected God's way, choosing the way of Satan the Devil instead. Because of their disobedience and rebellion, God told Adam and Eve the earth would come under a curse (Genesis 3:17-19). The result of sin is misery, suffering, violence, and death. This is why even the nature of most wild animals was changed, becoming fierce and hostile toward man and each other. Instead of assisting man during his lifetime, the earth became a hostile environment in which to live.
Thankfully, Jesus Christ will soon intervene in the affairs of mankind and establish God's Kingdom on earth. When this occurs, there will be a "restoration of all things" (Acts 3:21). God's creation will be restored to its original state before sin entered the world. Then the nature of animals will again be gentle and tame. There is a specific prophecy about this in Isaiah 11:
The wolf also shall dwell with the lamb, the leopard shall lie down with the young goat, the calf and the young lion and the fatling together; and a little child shall lead them. The cow and the bear shall graze; their young ones shall lie down together; and the lion shall eat straw like the ox. The nursing child shall play by the cobra's hole, and the weaned child shall put his hand in the viper's den. They shall not hurt nor destroy in all My holy mountain, for the earth shall be full of the knowledge of the LORD, as the waters cover the sea. (verses 6-9)
When Jesus Christ establishes God's government on the earth and imprisons the Devil (Revelation 20:1-3), the cause of sin will be removed. The nature of the animals—including poisonous snakes and spiders—will be changed, and the entire earth will experience peace and prosperity men have only dreamed of!