Selenoproteomes of different animal stages. The evolutionary roles of animals are shown in the schematic phylogenic tree on the left. All animals are abbreviated by 2 letters indicating their Latin names. The selenoprotein families are presented on the top. The red box indicates the existence of a certain family of selenoproteins in an organism. The green box indicates the existence of Cys-form proteins. The blank box indicates that neither selenoprotein nor Cys-form proteins of this family are detected.