Volvox

Volvox is a genus of green algae containing roughly 20 species of freshwater algae. Each colony of Volvox can contain between 500 to 60,000 cells, and thousands of these colonies can form together. The first scientist to observe Volvox was Leeuwenhoek in 1700. Due to their rapid growth, Volvox are widely studied to understand morphogenesis, and they can be found in freshwater habitats such as ponds and ditches, giving them a greenish hue.

Table of Contents:

Classification

Diagram

Characteristics

Life Cycle

Volvox Classification

Volvox is classified in the class Chlorophyceae due to its presence of chlorophyll.

| Domain | Eukaryota |

| Kingdom | Plantae |

| Phylum | Chlorophyta |

| Class | Chlorophyceae |

| Order | Chlamydomonadales |

| Family | Volvocaceae |

| Genus | Volvox |

Common species include: Volvox aureus, Volvox globator, V. carteri, V. barberi, etc.

Volvox Diagram

See also: Volvox

MCQs on Volvox

MCQs on Algae

Volvox Characteristics

  • Unicellular
  • Autotrophic
  • Colonies of up to 50,000 cells
  • Photosynthetic
  • Reproduce asexually by binary fission

A single colony of volvox looks like a ball of approximately 0.5 mm in diameter

The plant body of volvox is a hollow sphere known as a “coenobium,” with thousands of cells arranged in the periphery of the sphere.

The cells of coenobium are comprised of two types: germ cells and flagellated somatic cells

The extracellular matrix of coenobium is composed of glycoproteins.

Individual cells are typically spherical in shape

They have a cup-shaped chloroplast

Chloroplast contains pyrenoids

The cell has a nucleus, vacuoles, and an eyespot.

The two flagella of equal size located at the anterior of each cell work together to create a coordinated movement, allowing the colony to move through the water.

Each cell performs metabolic functions independently, including respiration, photosynthesis, and excretion.

The cytoplasmic strands formed during cell division connect adjacent cells.

The cells of the anterior region in the coenobium have larger eyespots than the cells of the posterior region, indicating a polarity.

Cells with larger eyespots are grouped together and facilitate phototaxis movement, which is used for light reception.

Volvox significantly contribute to the production of oxygen and are also a food source for many aquatic organisms.

Volvox aureus can multiply quickly and lead to a Harmful Algal Bloom (HAB). HABs are more common in warm waters with high nitrogen content.

Volvox Life Cycle

The life cycle of Volvox is haplontic, with the free-living haploid (n) gametophyte as the dominant stage, and the sporophyte only represented by the diploid zygote (2n).

Volvox demonstrate cell differentiation between reproductive and somatic cells

Most of the species reproduce asexually under favourable conditions and sexually under unfavourable conditions.

In Asexual Reproduction, reproductive cells known as Gonidia produce daughter colonies which, upon maturing, are released from the parent.

The gonidium undergoes multiple divisions, resulting in a colony of approximately 3200 cells.

Oogamous sexual reproduction is a type of sexual reproduction in which one sex (the male) produces small, motile gametes (sperm) and the other (the female) produces large, non-motile gametes (eggs).

Each coenobia may be either monoecious or dioecious.

Sexual reproduction is accomplished through the combination of male and female reproductive cells, known as spermatozoa and ova respectively.

An ovum is produced inside the oogonium. It is large and non-motile, and is green in colour due to the presence of chloroplasts. Additionally, it contains pyrenoids and has food storage.

Spermatozoa are produced inside the antheridium in a bunch. Each sperm is spindle-shaped with a pair of apical cilia.

Biflagellated antherozoids are released either collectively or singly

Antherozoids are drawn towards oogonium through chemotactic movement. The wall of the oogonia is broken down by the action of a proteolytic enzyme.

Out of many sperm that enter, only one antherozoid is able to successfully fertilize the egg.

The diploid zygote is formed when ova and spermatozoa undergo fertilization.

The formation of a zygote leads to the creation of a cyst and the cyst turns red due to the accumulation of hematochrome.

The zygote detaches from the parent after the disintegration of the parent and remains dormant for an extended period of time.

The zygote undergoes meiotic cell division to form four haploid cells.

They undergo multiple mitotic cell divisions to form a colony, and the life cycle continues.

Frequently Asked Questions

Volvox is a colonial organism made up of many unicellular organisms.

The genus Volvox is a type of colonial green algae, with each colony containing between 500 to 60,000 cells.

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Hi there!

How does Volvox reproduce sexually?

Sexual reproduction involves the formation and fusion of male and female reproductive cells, known as spermatozoa and ova, respectively. This type of reproduction is known as oogamy. An ovum is produced inside the oogonium, and spermatozoa are produced inside the antheridium. Biflagellate antherozoids are attracted to the oogonium by chemotactic movement, and after fertilization, a diploid zygote is formed. The zygote then undergoes meiosis to produce haploid cells.

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Volvox is a type of eukaryote.

Volvox is a genus of colonial green algae that are eukaryotic.

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Hello World!

Which class does Volvox belong to?

Volvox is a genus of green algae that form colonies of thousands of cells and are eukaryotic. Due to the presence of chlorophyll, Volvox belongs to the class Chlorophyceae.

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A Volvox is a genus of green algae that is made up of a colony of many smaller cells that are held together by a thick gelatinous wall. An example of a Volvox is Volvox aureus.

Volvox globator is the most common species of the genus Volvox, with around 20 species in total.

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