An adult male elephant is referred to as a bull while an adult female elephant is called a cow. A group of elephants is called a herd. Much like humans, the average mother elephant has only one baby at a time. Elephants hold the record for the longest gestation period; from conception until birth, an elephant pregnancy lasts for 22 months. Elephants are the largest of all land mammals and typically live for up to 70 years. While elephants only walk about four miles per hour, they are capable of swimming long distances. The elephant is a herbivore that spends about 16 hours per day eating and eats approximately 495 pounds of food every day.