Living in the eastern rainforests of Brazil, like all other callitrichids they are arboreal. Lion tamarins weigh up to 900 grams (32 oz) and are about 30 cm (12 in) long, with tails about 45 cm (18 in) long. They jump through trees using their fingers to hold on to branches; they use their claws to dig under the bark to search for insects to eat.