Kingdom: Protista (Under the Five Kingdom System) Phylum: Green Algae Division: Chlorophyta The Volvox is a plant-like Protist and a photosynthetic organism. The Volvox is a colonial Chlorophyte meaning that the “organism” is really a community of many individual cells. The “colony” itself is a hollow sphere. The green spots within each sphere are individual cells. The individual cells (green spots) are also photosynthetic organisms which provide food for the colony. It formed during the Triassic Period which was about 200 million years ago.

Each individual cell in the Volvox has 2 flagella and is connected by cytoplasm to the other cells. The individual cells in the hollow sphere are contained within a gelatinous matrix. If the individual cells leave the sphere or are otherwise isolated they CANNOT reproduce. Eventually the large colony sphere will release “daughter” colonies it holds within it. (as seen in the image above) Each Volvox colony can have up to 50,000 individual cells in it. Volvox colonies display phototaxis and are able to swim toward light sources.

Volvox colonies can reproduce both asexually and sexually (which is one similarity they share with sponges). Sexual Reproduction: Male Volvox colonies release sperm which are taken up by Female colonies (similar to sponges). Asexual Reproduction: These Volvox colonies contain both somatic cells, which don’t reproduce, and gonidia which eventually form the aforementioned daughter colonies. A video of Volvox reproduction: MYA

1. What do scientists mean when they describe the Volvox as a colony? 2. Describe one way in which the Volvox is similar to the sponge. 3. What Phylum and Division does the Volvox belong to? 4.What kind of (if any) Taxis does the Volvox display? 5.Briefly describe the Sexual and Asexual Reproduction of the Volvox. 6. Which part of the Volvox is photosynthetic? (Ex. The gelatinous matrix, the individual cells, the hollow sphere, etc.) 3A V7LTyJuAy4

Answers 1. The volvox is essentially a colony of individual cells which are all contained within a hollow sphere. 2. The male Volvox reproduces sexually by releasing sperm into it's environment which is later taken up by the female Volvox OR the Volvox can reproduce both sexually and asexually. 3. Phylum = Protista Division = Chlorophyta 4. Phototaxis 5. In asexual reproduction the volvox's gonidia cells (those that reproduce) form daughter colonies. Eventually the Volvox's outer membrane (the hollow sphere) will burst/split open and release these duaghter colonies. Sexual reproduction = male volvox release their sperm in the environment. Female Volvox's take them up. 6. The individual cells inside the Volvox are photosynthetic.