Elephants are the largest living land animals, with a gestation period of 22 months, the longest of any land animal. Giraffes are the tallest living animal species and the largest ruminant, averaging 4.3-5.2 meters tall for males and 1,200-830 kilograms for males and females, respectively. Monkeys are generally considered intelligent primates that are not prosimians or apes, with 264 known extant species that have tails unlike apes.