Snakes shed their skin as they grow to allow their skin to grow larger with their bodies. Without shedding, their skin would stretch too much. In winter, snakes find shelter in holes, burrows, caves or logs to hibernate dormant and inactive until temperatures warm again. The document also discusses elephant weights up to 5,500 kg for African bush elephants and how a chicken could not likely survive on Mars without genetically altered plants due to the hostile soil and lack of sufficient food and fresh water.