Great Ball of Cells - Volvox

Volvox is a colonial alga common in lakes, ponds and large puddles. It reproduces both asexually and sexually. During asexual reproduction 'daughter colonies' develop from germinal cells by cell division. Initially, this forms hollow balls of cells with their flagella pointed inward. Eventually, the developing daughter colony actually turns itself inside out - rather like a baloon being sucked backward so that the inside faces out. In this way the beating flagella face outward, providing motility to the colony. The daughter colonies inflate and burst through the parent sphere (which disintgrates), to begin the process again.

For a program that outlines aspects of micro- and macro- algae, see our video, Branches on the Tree of Life: Algae. For a treatment of the evolution of eukaryotes that outlines new perspectives on the relation of the different algae groups see our program: The Domains of Life.