Pandorina

Pandorina is a genus of green algae in the family Volvocaceae. It is a common freshwater genus, and has a cosmopolitan distribution. Along with other algae such as Volvox, Eudorina and Chlamydomonas, it is a model organism for studying the origins and evolution of multicellularity.

==Description== Pandorina is composed of 8, 16, or sometimes 32 cells, held together at their bases to form a globular or ellipsoidal colony surrounded by mucilage. The cells are ovoid or slightly narrowed at one end to appear keystone- or pear-shaped. Each cell has two flagella with two contractile vacuoles at its base, an eyespot, and a large cup-shaped chloroplast with at least one pyrenoid. The colonies co-ordinate their flagellar movement to create a rolling, swimming motion. Pandorina shows the beginnings of the colony polarity and differentiation seen in Volvox, with anterior cells having larger eyespots.