Volvox is a type of green algae or chlorophyte. Amongst the genera of green algae that form spherical colonies, volvox are the most developed. Their colonies contain flagellate cells that can be 50,000 in number and are embedded in coenobium or hollow muscilagenous spheres. These hollow spheres are formed of extracellular matrix which contains gelatinous glycoprotein. The cytoplasmic strands of volvox which connect the cells together make it greenish in color. Freshwater ditches, ponds, and shallow puddles are the places where these organisms thrive. The different volvox characteristics and facts makes this organism a model for studying fundamental questions pertaining to evolution. Let us delve into different volvox facts through the information presented in this write-up.
- The volvox grows well in eutrophic water bodies. Lakes that are rich in nutrients allow a prolific and healthy growth of this algae.
- Every single ovoid or spherical cell in volvox colonies possess two flagella. A pair of contractile vacuoles, along with single cup-shaped chloroplasts, are present at the base of these flagella.
- The cells of volvox can be single or biflagellate.
- Individual algal cells of volvox are attached to each other by means of cytoplasmic strands. These individual cells are characterized by the presence of red eye spots on their surface.
- Flagellar movement of cells present in volvox colonies is used for swimming (rolling motion) and also in changing the direction.
- The muscilage produced by every individual cell in the colony can be distinct or inconspicuous.
- In a particular colony of volvox, cells at the anterior possess phototactic abilities, which are attributed to larger eyespots.
- Posterior cells of the volvox colonies are more into other functions, like reproduction.
- Volvox is a polyphyletic organism, which means that it has multiple ancestral lineages. Different species of volvox have evolved from at least four different ancestral lineages.
- The size of volvox colonies can range from 100-6000 microns.
- Most of the volvox species are microscopic organisms, and therefore we cannot see them with naked eyes. However, few colonies are as big as 1 mm in diameter, making them easily visible.
- In the different stages of development of volvox, one can get to see their daughter cells and in few cases, even grand-daughter cells.
- One can find parasites feeding on cells of volvox in some colonies. A rotifer called Proales parasita thrives by feeding on cells of volvox.
The volvox regenerates both by sexual and asexual reproduction. The asexual cells, called gonidia, present at the posterior of volvox colonies contribute in asexual reproduction through repeated division. Growth of the gonads (daughter cells) takes place from cells that are present around the equator of the colony. The somatic/vegetative cells do not divide and are therefore unable to take part in reproduction. Sexual reproduction takes place by the fusion of sperms and egg cells. It is necessary to note that volvox can be monoecious or dioecious. The fertilization of male and female gametes in sexual reproduction leads to the formation of zygotes. The species called Volvox aureus has a smooth surface. Volvox globator, on the other hand, has zygotes that are star-shaped.
The different characteristics of volvox presented in the article should help in understanding more about these wonderful aquatic creatures. Their highly organized structure and way of functioning makes volvox an interesting topic of study.