Laid on leaves hanging over streams in tropical rainforests, glassfrog eggs are tasty snacks for snakes, insects and other predators until they hatch and drop into the streams to begin life as tadpoles. Until recently, biologists thought the eggs of most species were on their own during this vulnerable stage, without any help from mom or dad. In just a few species, fathers were known to care for their developing embryos, and biologists thought this paternal devotion had evolved from ancestors entirely lacking parental care.