Lemurs are primates endemic to the African island of Madagascar. There are around 100 species of lemurs, with a large portion of these species have only been identified in the past 20 years. Lemurs use their hands and feet to move nimbly through the trees, but cannot grip with their tails as some of the other primates can. Lemurs belong to the sub-order Strepsirhini along with bushbabies and lorises, and are nocturnal. Today's lemur species range in size from the tiny pygmy mouse lemur, weighing in at about 28 grams or one ounce, to the 7 kg (15 lb) indri lemur and sifaka. Lemurs are primarily herbivores, with the majority of their diet being comprised of fruits and leaves. Insects may also be on the menu, especially for smaller lemurs. Gestation periods for lemurs range from around two months for the small, mouse lemur, to 138-140 days for larger lemurs. Two offspring is not uncommon in lemur births.