during development in the order Volvocaceae that results in new colonies having their flagella facing outwards. During this process the asexual reproductive cells (gonidia) first undergo successive cell divisions to form a concave-to-cup-shaped embryo or plakea composed of a single cell layer. Immediately after, the cell layer is inside out compared with the adult configuration—the apical ends of the embryo protoplasts from which flagella are formed, are oriented toward the interior of the plakea. Then the embryo undergoes inversion, during which the cell layer inverts to form a spheroidal daughter colony with the apical ends and flagella of daughter protoplasts positioned outside. This process enables appropriate locomotion of spheroidal colonies of the Volvocaceae. The mechanism of inversion has been investigated extensively at the cellular and molecular levels using the model species, Volvox carteri. Habitats Volvox is a genus of freshwater algae found in ponds and ditches, even in shallow puddles. According to Charles Joseph Chamberlain, "The most favorable place to look for it is in the deeper ponds, lagoons, and ditches which receive an abundance of rain water. It has been said that where you find Lemna, you are likely to find Volvox; and it is true that such water is favorable, but the shading is unfavorable. Look where you find Sphagnum, Vaucheria, Alisma, Equisetum fluviatile, Utricularia, Typha, and Chara. Dr. Nieuwland reports that Pandorina, Eudorina and Gonium are commonly found as constituents of the green scum on wallows in fields where pigs are kept. The flagellate, Euglena, is often associated with these forms." History Antonie van Leeuwenhoek first reported observations of Volvox in 1700. After some drawings of Henry Baker (1753), Linnaeus (1758) would describe the genus Volvox, with two species: V. globator and V. chaos. Volvox chaos is an amoeba now known as Chaos (genus) sp. Evolution Ancestors of Volvox transitioned from single cells to form multicellular colonies at least , during the Triassic period. An estimate using DNA sequences from about 45 different species of volvocine green algae, including Volvox, suggests that the transition from single cells to undifferentiated multicellular colonies took about 35 million years. References External links Volvox description with pictures from a Hosei University website YouTube videos of Volvox: Volvox micro-motility in Lake Oroville, CA Life cycle and inversion Waltzing Volvox Spinning Volvox Volvox, one of the 7 Wonders of the Micro World by Wim van Egmond, from Microscopy-UK Volvox carteri at MetaMicrobe.com, with