SlideShare a Scribd company logo
2
Most read
4
Most read
5
Most read
Volvox- Life Cycle
Systematic Position
Occurrence of Volvox:
Volvox is a colonial alga, it grows in fresh water of pools, ponds etc.
It is represented by about 20 species. Single colony looks like a small
ball about 0.5 mm in diameter. In rainy season the colour of the
ponds becomes greenish due to rapid growth of Volvox.
Plant Body of Volvox:
Plant body of Volvox (L. volvere, the roll) is a coenobium, like a
hollow sphere of gelatinous substance (Fig. 3.52A, B). In the hollow
sphere, huge number of cells are arranged towards periphery in a
single layer (Fig. 3.52C, D). The number of cells varies from species
to species (500-1,000 in V. aureus, 2,000-3,000 in V. rousseletii)
and it ranges from 500-60,000.
Individual cell is typically like Chlamydomonas (except a few like V.
globator and V. rousseleti, those are Sphaerella type). The cells are
spherical in shape having cup-shaped chloroplast, with one or more
pyrenoid, an eye-spot, 2-6 contractilevacuoles and a single nucleus.
Each cell has two equal flagella placed anteriorly (Fig. 3.52D). Thus,
the coenobium is the aggregation of a number of Chlamydomonas-
like cells. But individual cell performs its own metabolic functions
like photosynthesis, respiration, nutrition, excretion etc.
Adjacent cells remain connected by cytoplasmic strands formed
during cell division (Fig. 3.52C). In some species like C. tertius, C.
mononae, cytoplasmic thread is absent. The central region of the
coenobium is generally hollow but in some cases it is filled with
gelatinous material (V. aureus) or water (V. globator).
The cells of the anterior region have large eye-spots than the
posterior region, indicating the clear polarity in the coenobium.
Important Features of Volvox:
1. Plant body is coenobium and consists of large number of
biflagellate, pear-shaped cells.
2. The cells of the coenobium are connected together by means of
protoplasmic strands.
3. Young coenobia consist of only vegetative cells and are concerned
with locomotion and food production.
4. Older coenobium consists of vegetative cells, daughter coenobia
and antherozoid mother cells and/or ovum mother cells.
5. Sexual reproduction is oogamous and the coenobia may be
monoecious or dioecious.
6. The female gametes or ova are large and non-motile, produced
singly inside the oogonium.
7. The male gametes or sperms are spindle- shaped, narrow with a
pair of apical cilia and are produced in bunch inside theantheridium.
8. The result of sexual union is the zygote, which on germination
develop into new coenobium either directly or by the formation of
single biflagellate zoospore.
Reproduction of Volvox:
Volvox reproducesboth asexually and sexually. Asexual reproduction
takes place during favourable condition, but the sexual reproduction
occurs during unfavourable condition i.e., towards the end of the
summer months.
Asexual Reproduction:
A few cells at the posterior side of the coenobium enlarge about 10
times. The cells withdraw their flagella and become more or less
round. They are pushed inside the colony during their development.
These cells are called gonidia(Fig. 3.53A) or parthenogonidiaor
autocolony initials. Thegonidium is separated from thevegetative
cells by its position and size.
Development of Daughter Colony:
The gonidium undergoes repeated divisions of about 15 or more
times and can develop more than 3,200 cells. Those cells ultimately
form a colony.
Initially the gonidium undergoes longitudinal division with respect
to the colony and form 2 cells (Fig. 3.53B), The second division is at
right angletothefirst oneand forms4 celled stage(Fig. 3.53C). These
ceils again divide longitudinally (3rd division) and form 8 celled
stage. The cells are arranged in such a pattern that their concave
inner surface faces towards the outer side of the colony.
This stage is called plakea stage or cruciate plate (Fig. 3.53D).
The 4th division forms 16 celled stage (Fig. 3.53E) and at that time it
becomes a hollow sphere with an opening towards the outer side,
called phialopore.
The division of cells continues up to the number specific for a
particular species. Thecells now face towards the centre(Fig. 3.53F).
This group of cells then undergoes inversion through thephialopore,
by which normal pattern of the colony is achieved.
Inversion:
During inversion a constriction appears at a point opposite to
phialopore. This constricted region becomes pushed gradually
towards the phialopore (Fig. 3.53G). Simultaneously the phialopore
becomes enlarged, through which the lower part comes out and the
edges of phialopore hang backwards.
With the help of inversion, the anterior side of thecells changes their
position from inner to the outer side and the position of phialopore
becomes reversed i.e., changes its position from outer to inner side
(Fig. 3.53H).
The phialopore gradually closes down and a completehollow sphere
is formed. After completion of inversion, the cells secrete their own
gelatinous cell wall and each develops two flagella. Thus, the
daughter colony is formed.
Many such colonies may develop in a coenobium and they swim
freely inside the gelatinous matrix of the mother coenobium (Fig.
3.52B). Later on the daughter coenobia come out by rupture or
disintegration of the mother colony. In some species like V. carteri
and V. africanus daughter colonies of 2-4 generations may remain
within the mother coenobium.
Sexual Reproduction:
Volvox reproduces sexually during unfavourable condition i.e.,
towards the end of growing season (late summer). The sexual
reproduction is oogamous. Somespecies (V. globator) is monoecious
and others (V. aureus) are dioecious.
Most of the monoecious species are of protandrous type (i.e.,
antheridia develop and matureearlier than oogonium). Somecells of
theposterior regionof thecolony withdraw their flagella and develop
into reproductive bodies called gametangia. The male gametangia
are called antheridiaand the female as oogonia.
Development of Antheridium:
During development of antheridium, an antheridial initial becomes
differentiated from the colony. It is like a gonidium, which is
aflagellated, larger in size than vegetative cells and contains dense
cytoplasm with a single nucleus.
The cell undergoes repeated longitudinal divisions like the asexual
stage and forms generally about 64-128 cells (though the number
varies from 16-512, depending on species). Like the asexual stage the
cells are arranged in groupsand then undergoinversion bywhich the
anterior side of the cells faces towards outer side (Fig. 3.54).
Each cell develops into unicellular, elongated, fusiform, naked and
biflagellate antherozoid. The antherozoids are released individually.
In some species they are also released in groups.
Development of Oogonium:
Single vegetative cell of thecolony at the posterior side withdraws its
flagella, enlarges in size and become a more or less flask-shaped
oogonium. The entire protoplast without undergoing any division,
forms an uninucleate non-flagellated egg or female gametophyte
(Fig. 3.55A).
The egg or female gametophyte is spherical, uninucleate, non-
flagellated, green in colour and has parietal chloroplast. It has many
pyrenoids and large amount of reserve food. The mouth of the flask-
shaped oogonium opens towards the outer surface of the colony.
Fertilisation:
After maturation, the anthrozoids (= sper- matozoids) are liberated
from the antheridium either singly or in mass. They move in water
and get attractedby the chemotactic stimulation to thesurface of the
oogonium.
A few antherozoids enter near the egg (Fig. 3.55B) by breaking the
oogonial wall with the help of proteolytic enzyme probably secreted
by the antherozoids. Out of many antherozoids
entered into the oogonium only one succeeds to fertilise the egg and
forms a zygote.
Zygote:
The zygote secretes a thick wall around itself (Fig. 3.55C). It
accumulates the haematochrome and becomes red in colour. The
wall of thezygote may be smoothly, (V. monanae, V. globator etc.) or
spiny (V. spermatophora etc.). Zygote is liberated by the
disintegration of the mother wall and remains dormant for a long
period.
Germination of Zygote:
During favourable condition the zygote germinates. Before
germination, the diploid (2n) nucleus (Fig. 3.56A) of the zygote
undergoes meiotic division and forms 4 haploid cells (Fig. 3.56B, C).
Further development of zygote varies with species:
1. In V. minor and K aureus, after meiotic division the cells undergo
repeated mitotic division and form a new colony as formed during
asexual reproduction (Fig. 3.56D, E and F).
2. In V. rousseletii, out of 4 haploid cells generally only one survives.
The outer wall (exospore) of the zygote breaks and the inner wall
(endospore) comes out in the form of vesicle containing a single
biflagellate meiospore.
The meiospore is then liberated in the water by breaking the inner
wall i.e., endospore. The biflagellate meiospore then undergoes
divisions like the development of daughter colony during asexual
process and forms new coenobium.
3. In V. campensis, out of many zoospores formed in the oogonium
by zygotic division only one survives and others degenerate. The
surviving one comes out and by repeated mitotic division it forms a
new colony like asexual reproduction.
Indian Species:
V. aureus, V. merrille, V. rousseleti, V. africanus, V. globator and V.
prolificus are very common.
Life Cycle of Volvox:
Fig. 3.57 and 3.58 depict life cycle of Volvox.
Volvox-Life Cycle and rolling algae in bsc 1 sem

More Related Content

PPTX
PDF
5 2 -pinus
PPTX
PPTX
Oedogonium
PPTX
Petromyzon -External features and comparative hagfish
PPTX
Gymnosperms - General characteristics and Economic importance.pptx
PPT
Bryophyta General Characteristics and Economic Importance - Copy.ppt
PPTX
5 2 -pinus
Oedogonium
Petromyzon -External features and comparative hagfish
Gymnosperms - General characteristics and Economic importance.pptx
Bryophyta General Characteristics and Economic Importance - Copy.ppt

What's hot (20)

PPTX
PPTX
periderm, new 2023.pptx
PPTX
Reproduction in volvox
PDF
T.s. dicot root
PPTX
Life cycle of volvox and...
PDF
PPSX
Lec4 bacillariophyceae (the diatoms)
DOCX
Marchantia important points
PPTX
PSILOTUM : structure, morphology, anatomy, reproduction , life cycle etc.
PDF
TARGIONIA.pdf msc botany plant structure
PPTX
Chara algae Morphology Cell Structure Reproduction
DOCX
Development of blanoglossus( b.sc.ii)zoology
PPT
Chlamydomonas
PPTX
Volvox.pptx
PPTX
Marchantia
PPTX
Pteris : features, anatomy, morphology and lifecycle
PPTX
Batrachospermum.pptx
PPTX
Volvox ppt
PPTX
Reproduction in Riccia
periderm, new 2023.pptx
Reproduction in volvox
T.s. dicot root
Life cycle of volvox and...
Lec4 bacillariophyceae (the diatoms)
Marchantia important points
PSILOTUM : structure, morphology, anatomy, reproduction , life cycle etc.
TARGIONIA.pdf msc botany plant structure
Chara algae Morphology Cell Structure Reproduction
Development of blanoglossus( b.sc.ii)zoology
Chlamydomonas
Volvox.pptx
Marchantia
Pteris : features, anatomy, morphology and lifecycle
Batrachospermum.pptx
Volvox ppt
Reproduction in Riccia
Ad

Similar to Volvox-Life Cycle and rolling algae in bsc 1 sem (20)

PDF
Developement of Embryo
PPTX
xanthophyceae-life history of Vaucheria.pptx
DOCX
BOTANY .docx
PPTX
STUDY OF CLEAVAGE BLASTULA, GASTRULA.pptx
PPTX
PPTX
Mastigomycotina
PPTX
Discription of the biology of nematodes.pptx
PPTX
My ppt Ectocarpus (1).pptx.................
PPT
Cleavage
PDF
Plant reproduction responses
PPTX
Vaucheria ppt.pptx
PPT
Reproduction in algae........
PPSX
plant reprodutive system
PPTX
Hydrodictyon
PPTX
Reproduction of Algae | Vegetative, Asexual & Sexual reproduction
PDF
Volvox : The genus of algae , volvox study
PPTX
Life processes in living organism part 2
PDF
Reproduction of plants and simple animals
Developement of Embryo
xanthophyceae-life history of Vaucheria.pptx
BOTANY .docx
STUDY OF CLEAVAGE BLASTULA, GASTRULA.pptx
Mastigomycotina
Discription of the biology of nematodes.pptx
My ppt Ectocarpus (1).pptx.................
Cleavage
Plant reproduction responses
Vaucheria ppt.pptx
Reproduction in algae........
plant reprodutive system
Hydrodictyon
Reproduction of Algae | Vegetative, Asexual & Sexual reproduction
Volvox : The genus of algae , volvox study
Life processes in living organism part 2
Reproduction of plants and simple animals
Ad

More from Bhagirath Gogikar (20)

PDF
Ultra_structure_of_Bacteria in 1 unit of botany
PPTX
Secondary growth and anomalous secondary growth.pptx
PDF
Bacterial-genetics for msc students with explanation
PDF
2. Fluorescence in Botany Emerging Applications and methodology.pdf
PDF
introductionimportanceandscopeofhorticulture-240207100812-144e804b.pdf
PPTX
Evolution of crop Plants in agriculture .pptx
PPTX
Introduction-to-Sustainable-Farming.pptx
PPTX
Introduction-to-Bio-Enzyme-Technology.pptx
PPTX
Introduction,importance and scope of horticulture.pptx
PPTX
Asteraceae family.pptx for NEET and EAMCET
PDF
MSB Class 11 Biology-Ch9.pdf for NEET and State
PDF
EffectofBio-EnzymeintheTreatmentofFresh.pdf
PDF
vernonia anthelmintica plant profile with phyto chemistry
PPTX
49-GBR-SDPT Seminar.pptx
PPTX
4. Fabaceae.pptx
DOCX
plantae.docx
PDF
Departmental Library.pdf
PDF
Student Study Projects 6.pdf
PDF
DOCX
Jignasa -II.docx
Ultra_structure_of_Bacteria in 1 unit of botany
Secondary growth and anomalous secondary growth.pptx
Bacterial-genetics for msc students with explanation
2. Fluorescence in Botany Emerging Applications and methodology.pdf
introductionimportanceandscopeofhorticulture-240207100812-144e804b.pdf
Evolution of crop Plants in agriculture .pptx
Introduction-to-Sustainable-Farming.pptx
Introduction-to-Bio-Enzyme-Technology.pptx
Introduction,importance and scope of horticulture.pptx
Asteraceae family.pptx for NEET and EAMCET
MSB Class 11 Biology-Ch9.pdf for NEET and State
EffectofBio-EnzymeintheTreatmentofFresh.pdf
vernonia anthelmintica plant profile with phyto chemistry
49-GBR-SDPT Seminar.pptx
4. Fabaceae.pptx
plantae.docx
Departmental Library.pdf
Student Study Projects 6.pdf
Jignasa -II.docx

Recently uploaded (20)

PPTX
Microbes in human welfare class 12 .pptx
PPT
Mutation in dna of bacteria and repairss
PDF
S2 SOIL BY TR. OKION.pdf based on the new lower secondary curriculum
PPTX
endocrine - management of adrenal incidentaloma.pptx
PDF
Looking into the jet cone of the neutrino-associated very high-energy blazar ...
PPTX
Introcution to Microbes Burton's Biology for the Health
PDF
Science Form five needed shit SCIENEce so
PPT
Animal tissues, epithelial, muscle, connective, nervous tissue
PPTX
GREEN FIELDS SCHOOL PPT ON HOLIDAY HOMEWORK
PPT
LEC Synthetic Biology and its application.ppt
PPTX
Fluid dynamics vivavoce presentation of prakash
PPTX
TORCH INFECTIONS in pregnancy with toxoplasma
PPTX
BODY FLUIDS AND CIRCULATION class 11 .pptx
PDF
Is Earendel a Star Cluster?: Metal-poor Globular Cluster Progenitors at z ∼ 6
PDF
The Land of Punt — A research by Dhani Irwanto
PDF
Communicating Health Policies to Diverse Populations (www.kiu.ac.ug)
PDF
Warm, water-depleted rocky exoplanets with surfaceionic liquids: A proposed c...
PDF
BET Eukaryotic signal Transduction BET Eukaryotic signal Transduction.pdf
PPTX
BIOMOLECULES PPT........................
PPTX
Hypertension_Training_materials_English_2024[1] (1).pptx
Microbes in human welfare class 12 .pptx
Mutation in dna of bacteria and repairss
S2 SOIL BY TR. OKION.pdf based on the new lower secondary curriculum
endocrine - management of adrenal incidentaloma.pptx
Looking into the jet cone of the neutrino-associated very high-energy blazar ...
Introcution to Microbes Burton's Biology for the Health
Science Form five needed shit SCIENEce so
Animal tissues, epithelial, muscle, connective, nervous tissue
GREEN FIELDS SCHOOL PPT ON HOLIDAY HOMEWORK
LEC Synthetic Biology and its application.ppt
Fluid dynamics vivavoce presentation of prakash
TORCH INFECTIONS in pregnancy with toxoplasma
BODY FLUIDS AND CIRCULATION class 11 .pptx
Is Earendel a Star Cluster?: Metal-poor Globular Cluster Progenitors at z ∼ 6
The Land of Punt — A research by Dhani Irwanto
Communicating Health Policies to Diverse Populations (www.kiu.ac.ug)
Warm, water-depleted rocky exoplanets with surfaceionic liquids: A proposed c...
BET Eukaryotic signal Transduction BET Eukaryotic signal Transduction.pdf
BIOMOLECULES PPT........................
Hypertension_Training_materials_English_2024[1] (1).pptx

Volvox-Life Cycle and rolling algae in bsc 1 sem

  • 1. Volvox- Life Cycle Systematic Position Occurrence of Volvox: Volvox is a colonial alga, it grows in fresh water of pools, ponds etc. It is represented by about 20 species. Single colony looks like a small ball about 0.5 mm in diameter. In rainy season the colour of the ponds becomes greenish due to rapid growth of Volvox. Plant Body of Volvox: Plant body of Volvox (L. volvere, the roll) is a coenobium, like a hollow sphere of gelatinous substance (Fig. 3.52A, B). In the hollow sphere, huge number of cells are arranged towards periphery in a single layer (Fig. 3.52C, D). The number of cells varies from species to species (500-1,000 in V. aureus, 2,000-3,000 in V. rousseletii) and it ranges from 500-60,000. Individual cell is typically like Chlamydomonas (except a few like V. globator and V. rousseleti, those are Sphaerella type). The cells are spherical in shape having cup-shaped chloroplast, with one or more pyrenoid, an eye-spot, 2-6 contractilevacuoles and a single nucleus. Each cell has two equal flagella placed anteriorly (Fig. 3.52D). Thus, the coenobium is the aggregation of a number of Chlamydomonas- like cells. But individual cell performs its own metabolic functions like photosynthesis, respiration, nutrition, excretion etc. Adjacent cells remain connected by cytoplasmic strands formed during cell division (Fig. 3.52C). In some species like C. tertius, C. mononae, cytoplasmic thread is absent. The central region of the coenobium is generally hollow but in some cases it is filled with gelatinous material (V. aureus) or water (V. globator).
  • 2. The cells of the anterior region have large eye-spots than the posterior region, indicating the clear polarity in the coenobium. Important Features of Volvox: 1. Plant body is coenobium and consists of large number of biflagellate, pear-shaped cells. 2. The cells of the coenobium are connected together by means of protoplasmic strands. 3. Young coenobia consist of only vegetative cells and are concerned with locomotion and food production. 4. Older coenobium consists of vegetative cells, daughter coenobia and antherozoid mother cells and/or ovum mother cells. 5. Sexual reproduction is oogamous and the coenobia may be monoecious or dioecious. 6. The female gametes or ova are large and non-motile, produced singly inside the oogonium. 7. The male gametes or sperms are spindle- shaped, narrow with a pair of apical cilia and are produced in bunch inside theantheridium. 8. The result of sexual union is the zygote, which on germination develop into new coenobium either directly or by the formation of single biflagellate zoospore. Reproduction of Volvox:
  • 3. Volvox reproducesboth asexually and sexually. Asexual reproduction takes place during favourable condition, but the sexual reproduction occurs during unfavourable condition i.e., towards the end of the summer months. Asexual Reproduction: A few cells at the posterior side of the coenobium enlarge about 10 times. The cells withdraw their flagella and become more or less round. They are pushed inside the colony during their development. These cells are called gonidia(Fig. 3.53A) or parthenogonidiaor autocolony initials. Thegonidium is separated from thevegetative cells by its position and size. Development of Daughter Colony: The gonidium undergoes repeated divisions of about 15 or more times and can develop more than 3,200 cells. Those cells ultimately form a colony. Initially the gonidium undergoes longitudinal division with respect to the colony and form 2 cells (Fig. 3.53B), The second division is at right angletothefirst oneand forms4 celled stage(Fig. 3.53C). These ceils again divide longitudinally (3rd division) and form 8 celled stage. The cells are arranged in such a pattern that their concave inner surface faces towards the outer side of the colony. This stage is called plakea stage or cruciate plate (Fig. 3.53D). The 4th division forms 16 celled stage (Fig. 3.53E) and at that time it becomes a hollow sphere with an opening towards the outer side, called phialopore. The division of cells continues up to the number specific for a particular species. Thecells now face towards the centre(Fig. 3.53F). This group of cells then undergoes inversion through thephialopore, by which normal pattern of the colony is achieved. Inversion: During inversion a constriction appears at a point opposite to phialopore. This constricted region becomes pushed gradually towards the phialopore (Fig. 3.53G). Simultaneously the phialopore
  • 4. becomes enlarged, through which the lower part comes out and the edges of phialopore hang backwards. With the help of inversion, the anterior side of thecells changes their position from inner to the outer side and the position of phialopore becomes reversed i.e., changes its position from outer to inner side (Fig. 3.53H). The phialopore gradually closes down and a completehollow sphere is formed. After completion of inversion, the cells secrete their own gelatinous cell wall and each develops two flagella. Thus, the daughter colony is formed. Many such colonies may develop in a coenobium and they swim freely inside the gelatinous matrix of the mother coenobium (Fig. 3.52B). Later on the daughter coenobia come out by rupture or disintegration of the mother colony. In some species like V. carteri and V. africanus daughter colonies of 2-4 generations may remain within the mother coenobium. Sexual Reproduction: Volvox reproduces sexually during unfavourable condition i.e., towards the end of growing season (late summer). The sexual reproduction is oogamous. Somespecies (V. globator) is monoecious and others (V. aureus) are dioecious.
  • 5. Most of the monoecious species are of protandrous type (i.e., antheridia develop and matureearlier than oogonium). Somecells of theposterior regionof thecolony withdraw their flagella and develop into reproductive bodies called gametangia. The male gametangia are called antheridiaand the female as oogonia. Development of Antheridium: During development of antheridium, an antheridial initial becomes differentiated from the colony. It is like a gonidium, which is aflagellated, larger in size than vegetative cells and contains dense cytoplasm with a single nucleus. The cell undergoes repeated longitudinal divisions like the asexual stage and forms generally about 64-128 cells (though the number varies from 16-512, depending on species). Like the asexual stage the cells are arranged in groupsand then undergoinversion bywhich the anterior side of the cells faces towards outer side (Fig. 3.54). Each cell develops into unicellular, elongated, fusiform, naked and biflagellate antherozoid. The antherozoids are released individually. In some species they are also released in groups. Development of Oogonium: Single vegetative cell of thecolony at the posterior side withdraws its flagella, enlarges in size and become a more or less flask-shaped oogonium. The entire protoplast without undergoing any division, forms an uninucleate non-flagellated egg or female gametophyte (Fig. 3.55A).
  • 6. The egg or female gametophyte is spherical, uninucleate, non- flagellated, green in colour and has parietal chloroplast. It has many pyrenoids and large amount of reserve food. The mouth of the flask- shaped oogonium opens towards the outer surface of the colony. Fertilisation: After maturation, the anthrozoids (= sper- matozoids) are liberated from the antheridium either singly or in mass. They move in water and get attractedby the chemotactic stimulation to thesurface of the oogonium. A few antherozoids enter near the egg (Fig. 3.55B) by breaking the oogonial wall with the help of proteolytic enzyme probably secreted by the antherozoids. Out of many antherozoids entered into the oogonium only one succeeds to fertilise the egg and forms a zygote. Zygote: The zygote secretes a thick wall around itself (Fig. 3.55C). It accumulates the haematochrome and becomes red in colour. The wall of thezygote may be smoothly, (V. monanae, V. globator etc.) or spiny (V. spermatophora etc.). Zygote is liberated by the disintegration of the mother wall and remains dormant for a long period. Germination of Zygote: During favourable condition the zygote germinates. Before germination, the diploid (2n) nucleus (Fig. 3.56A) of the zygote undergoes meiotic division and forms 4 haploid cells (Fig. 3.56B, C).
  • 7. Further development of zygote varies with species: 1. In V. minor and K aureus, after meiotic division the cells undergo repeated mitotic division and form a new colony as formed during asexual reproduction (Fig. 3.56D, E and F). 2. In V. rousseletii, out of 4 haploid cells generally only one survives. The outer wall (exospore) of the zygote breaks and the inner wall (endospore) comes out in the form of vesicle containing a single biflagellate meiospore. The meiospore is then liberated in the water by breaking the inner wall i.e., endospore. The biflagellate meiospore then undergoes divisions like the development of daughter colony during asexual process and forms new coenobium. 3. In V. campensis, out of many zoospores formed in the oogonium by zygotic division only one survives and others degenerate. The surviving one comes out and by repeated mitotic division it forms a new colony like asexual reproduction. Indian Species: V. aureus, V. merrille, V. rousseleti, V. africanus, V. globator and V. prolificus are very common.
  • 8. Life Cycle of Volvox: Fig. 3.57 and 3.58 depict life cycle of Volvox.