Volvocaceae

Volvocaceae are a family of unicellular or colonial biflagellate algae, including the typical genus Volvox, and are collectively known as the volvocine algae. The family was named by Ehrenberg in 1834, and it is known in older classifications as the Volvocidae. All species are colonial and typically inhabit freshwater environments. They are particularly useful as model organisms for studying the evolution of multicellularity, the evolution of sex, and cellular motion and mechanics.

==Description== Volvocine algae consist of multiple, biflagellate cells. Each cell has a cell membrane, a central nucleus, multiple mitochondria, and one large chloroplast with an associated stigma (also known an eyespot). The stigma is reddish due to the presence of rhodopsin. The apical end of the cell has two equal-length flagella; the flagella beat in a manner similar to a breaststroke.