The gestation period of the elephant is 22 months -- the most of any mammal in the animal kingdom! The baby calf weighs around 120 kg / 265 lbs. What a heavy baby! Nevertheless it is still vulnerable, hunted by lions that prey on baby elephants and the weaklings in the herd. If the baby elephant survives to adulthood, it can reach more than 4500 kg / 10,000 lbs in weight and live for as long as eighty years.