Bromeliads are related to the pineapple family and the pineapple and Spanish moss are two of the most common bromeliads. Their thick, waxy leaves make a bowl shape in the centre for catching rainwater. Some bromeliads can hold several litres of water and are miniature ecosystems in themselves providing homes for creatures such as frogs and their tadpoles, salamanders, snails, beetles and mosquito larvae. The dying plants decompose and give nutrients to the plant. There are more than 2,700 species of bromeliads in the Amazon rainforest, and about one-third of them are endangered. Some bromeliads are so heavy that they can break the trees from which they grow. Poison arrow frogs lay their eggs in the endangered tank bromeliad.