在非洲卡拉哈里沙漠，由于雨量稀少，所有的动物自出生就要面临干燥的无情考验。由于纳马夸公沙鸡胸部的羽毛吸水性非常强，为孩子寻水的责任就自然而然落到了它们“胸”上——公沙鸡每天都会到湖边把羽毛在水里浸湿后再飞回家，以此满足小沙鸡对水的渴求。
　　
　达尔文蛙——用嘴抚育幼儿

　　
　　Frog（达尔文蛙）:The male Darwin frog hatches his eggs in apouch(小袋子，文中指“达尔文蛙的声囊”)in his mouth. He can eat and continue about his business until his tadpoles(蝌蚪)lose their tails, become tiny frogs, and jump out of his mouth!