Volvox are colonial flagellates and a very popular organism for classroom observations. The colony is large, measuring from 100-6000 microns across.

The colony is comprised of many single, bi-flagellated cells connected together by protoplasmic strands. It forms a hollow, green sphere. Individual cells have a red eyespot and with chloroplasts, can make food from sunlight. Daughter colonies grow within this main colony and eventually break free and develop as a parent colony.

Small animals like Rotifers prey on the Volvox.

The cells are vegetative (i.e. they do not reproduce) except for a few near the back, which develop into new colonies. Eventually the parent bursts and the daughter colonies evert. Sexual reproduction is oogamous - one gender produces small motile gametes and the other non-motile gametes.

Volvox is found in ponds and ditches, and even in shallow rain puddles. Volvox are readily available from science supply companies.