Eustigmatophyceae

Eustigmatophyceae is a small but important class of unicellular algae, mainly known for their high lipid content and industrial importance (biofuel, aquaculture).

General Characteristics of Eustigmatophyceae

• Mostly unicellular; rarely form simple colonies
• Cells are non-motile (flagella absent in vegetative stage)
• Found in marine as well as freshwater habitats
• Eukaryotic algae with a true nucleus
• Cell wall generally thick, mainly composed of cellulose
• Usually possess a single parietal chloroplast
• Chloroplast surrounded by two membranes
• Thylakoids arranged in triplets (three stacked thylakoids)
• Pyrenoids generally absent

Photosynthetic Pigments

• Chlorophyll a
• Chlorophyll c
• Carotenoids (especially violaxanthin)
• Fucoxanthin absent
• Phycobilins absent

Reserve Food Material

• Stored mainly as:
  • Oil (lipids)
  • Leucosin (chrysolaminarin-like polysaccharide)
• Reserve food stored in the cytoplasm

Reproduction

Mode of Reproduction

• Only asexual reproduction
• Sexual reproduction absent

Asexual Reproduction Methods

🔹 Vegetative Cell Division

• Occurs by mitotic division
• Parent cell divides into two daughter cells
• Each daughter cell grows independently

🔹 Autospore Formation

• Parent cell divides internally to form non-motile autospores
• Autospores are released after rupture of the parent wall
• Each autospore develops into a new individual

Life Cycle of Eustigmatophyceae

Type of Life Cycle

• Asexual
• Monogenetic
• Haploid (n)

Life Cycle Stages (Step-wise)

Vegetative Cell (n)

• Unicellular, non-motile algal cell
• Contains:
  • True nucleus
  • Single parietal chloroplast
• Grows under favorable conditions

Asexual Reproduction

Occurs by two methods:

(A) Binary / Mitotic Cell Division

• Nucleus divides by mitosis
• Cytoplasm divides
• Two identical haploid daughter cells formed

(B) Autospore Formation

• Parent cell divides internally
• 2–8 non-motile autospores formed
• Parent wall ruptures and releases autospores

Liberation & Growth

• Autospores or daughter cells are released
• Each develops into a new vegetative cell (n)