OrderVOLVOCALESReporter:

Adrian Fabian Alcaraz

Proud BS Bio 4A

Includes about 60 genera and 500 species

Distinguishing FeaturesUnicellular or colonialMotile throughout their life or forming colonies of

palmelloid forms or dendroid formsUsually fresh waterChloroplast are usually cup or basin shaped with a

single pyrenoid.Asexual reproduction by biflagellate

zoospores‚ aplanospores ‚ or palmella stagesSexual reproduction varies from isogamy to oogamy

Suborder Chlamydomonadineae Family Chlamydomonadaceae Family Sphaerellaceae Family Polyblepharidaceae Family Phacotaceae

Suborder Tetrasporineae Family Tetrasporaceae Family Palmellaceae

Suborder Chlorodendrineae Family Chlorodendraceae

Family Chlamydomonadaceae

Distinguishing FeaturesUnicellularMay be biflagellate or quadriflgellateAsexual reproduction takes place by

zoospores or palmella stagesSexual reproduction is mostly

isogomous

Habitat andOccuranceWidely distributed on fresh water

(rainwater ponds‚ pools‚ ditches‚ laboratory aquaria‚ moist soils)

Waters rich in ammonium compoundsSalt waters (C. halophila)Snow (C. yellowstonensis)

StructureMeasure about 0.02mmSpherical‚ ovoid‚ sub-cylindrical ‚ ellipsoidalChloroplast:

Single cup shape Reticulate Stellate Discoid

Single pyrenoid ‚ some lack pyrenoidTwo contractile vacuoles at the base of the flagellaTiny photoreceptive eye-spots at the anterior end.

cellulosic wall

cell membrane

chloroplast

mitochondria

nucleus

flagella

eyespot

cytosol

starchpyrenoid

Chlamydomonas contractile vacuole

Discoid ChloroplastReticulate ChloroplastSingle cup ChloroplastStellate Chloroplast

ReproductionAsexual reproduction:

Zoospores Aplanospore formation Hypnospores Palmella stage

ReproductionSexual reproduction:

Isogamous reproduction

ReproductionSexual reproduction:

Anisogamous reproduction

ReproductionSexual reproduction:

Oogamous reproduction

ReproductionZygotes and its germination

Life Cycle

Nice to Know

Family VolvocaceaePANDORINA

Distinguishing FeaturesIncludes all motile colonial generaCells of the colony lie in a disc or in a hollow

sphere. The number in a colony is fixed an is a multiple of two.

Asexual reproduction is by daughter colonySexual reproduction ranges rom isogamy to

oogamy

Habitat andOccuranceWidely distributed on fresh water

(ponds‚ ditches)

StructureMotile colonySubspherical to ellipsoidal in shapeIt consists of usually 16 (rarely 8 or 32)

biflagellate cells embedded in a gelatinous matrix

ReproductionAsexual reproduction:Sexual reproduction:

Family VolvocaceaeEUDORINA

Habitat andOccuranceWidely distributed on fresh water

(ponds‚ ditches)

StructureCoenobia are usually spherical or ovoid an larger

than PandorinaComposed of 32 (rarely 16 or 64) cells

ReproductionAsexual reproduction:Sexual reproduction:

Family Sphaerellaceae

Distinguishing FeaturesMotile forms which cells lie in a disc or a

hollow sphereNumber of cells is definite and constant

rom juvenile to adult (coenobium)Asexual reproduction by formation of

daughter coloniesSexual reproduction varies rom isogamy to

oogamy through anisogamy

Family SphaerellaceaeVOLVOX

Habitat andOccuranceWidely distributed on fresh water

(rainwater ponds‚ pools‚ ditches‚ sometimes lakes)

The coenobia appear in rainy season and disappear with the beginning of summer

StructureA colony is comprised of 500-60,000 cellsAll cells are arranged in a single layer within a

periphery of colonial matrixCovered by a marked mucilaginous lamellaInternally occupied by a gelatinous material

ReproductionAsexual reproductionSexual reproduction