11+ Unicellular Algae Examples: Detailed Facts

Unicellular algae examples can be found in various different phylum classified under kingdom Protista.

Unicellular or acellular algae are both prokaryote and eukaryote organisms containing chlorophyll. The few main phylum in which unicellular algae can be classified are; Cyanophyta, Glaucophyta, Euglenophyta, Chrysophyta, Pyrrophyta, Charophyta and a few Rhodophyta.

A few examples of unicellular algae are,

Unicellular algae are mostly phytoplankton found in both marine and freshwater habitats and some unicellular algae are found in terrestrial habitats. Many of these algae are extremophiles.

Based on the presence of either Rhizopodia or flagella, unicellular algae can be either motile or non-motile.

Cyanophyta: Blue-green algae

Commonly referred to as cyanobacteria and are prokaryotic algae. They are free-living, gram-negative bacteria, usually containing ‘chlorophyll a’ for photosynthesis. They have naked, circular fibrils of DNA in their protoplasm.

Gloeothece fuscolutea

  • Phylum: Cyanobacteria
  • Class: Cyanophyceae
  • Subclass: Oscillatoriophycideae
  • Order: Chroococcales
  • Family: Chroococcaceae
  • Genus: Gloeothece
  • Species: fuscolutea.

A rod-shaped or ovoid cyanobacterium without internal thylakoids. They are free-living, freshwater cyanobacteria with layered mucilaginous sheath. They are one of the most primitive algae based on their nucleic acid sequencing.

Prochlorococcus marinus

  • Phylum: Cyanobacteria
  • Class: Cyanophyceae
  • Subclass: Synechococcophycideae
  • Order: Synechococcales
  • Family: Synechococcaceae
  • Genus: Prochlorococcous
  • Species: marinus

These small, marine, picoplankton are one of the most abundant and smallest photosynthetic organisms in Earth. They contain chlorophyll a and b, and lack phycobilin pigments. They are free-living, non-motile, coccoid cyanobacteria found in euphotic zones of world’s tropical oceans at a temperature range of 10-33o C.

unicellular algae examples
Fig: Prochlorococcus MED4” by Chisholm Lab is marked with CC0 1.0. Copy text

Synechococcus arcuatus

  • Phylum: Cyanobacteria
  • Class: Cyanophyceae
  • Subclass: Synechococcophycideae
  • Order: Synechococcales
  • Family: Synechococcaceae
  • Genus: Synechococcus
  • Species: arcuatus

These freshwater, motile, cylindrical coccoid picoplankton contain chlorophyll a as photosynthetic pigments and phycobilin as accessory pigments.

Glaucophyta:

They contain endosymbiotic cyanobacteria in their cytoplasm instead of chlorophyll. The endosymbiotic theory of chloroplast evolution is evident from this symbiotic association. The endosymbiotic cyanobacteria are called cyanelles and the host is called cyanome.

unicellular algae examples
Fig: “Glaucophyta” by JJT1982 is licensed under CC BY 2.0. Copy text

Cyanophora paradoxa

  • Phylum: Glaucophyta
  • Class: Glaucophyceae
  • Order: Glaucocystales
  • Family: Glaucocystaceae
  • Genus: Cyanophora
  • Species: paradoxa

Freshwater flagellate with two cyanelles present in protoplasm. Each cyanelles have a central dense body and an inner ring each, in the stroma inside the plasma membrane.

Glaucocystis duplex-

  • Phylum: Glaucophyta
  • Class: Glaucophyceae
  • Order: Glaucocystales
  • Family: Glaucocystaceae
  • Genus: Glaucocystis
  • Species: duplex

These freshwater organisms have two groups of cyanelles, one on each side of nucleus. They have reduced flagella in cell wall. These unicellular algae proliferate through asexual reproduction.

Euglenophyta:

These motile, aquatic unicellular algae have chlorophyll a &b as their respiratory pigments, and flagella with fibrillar hairs in a row. Their nucleus is mesokaryotic in nature. Their cellular body is covered by plasma membrane, underneath which lies pellicle, that is made of repeating proteinaceous units called strips and microtubules.

Peranema trichophorum-

  • Phylum: Euglenophycota
  • Class: Euglenophyceae
  • Order: Heteronematales
  • Family: Paranemataceae
  • Genus: Peranema
  • Species: trichophorum

These free-living, phagocytic organelles are mostly found in freshwaters. They have specialized ‘food vacuole’ for phagocytosis.

unicellular algae examples
Fig: “Peranema (Flagellat) – 630x” by Picturepest is licensed under CC BY 2.0. Copy text

Euglena gracilis-

  • Phylum: Euglenophycota
  • Class: Euglenophyceae
  • Order: Euglenales
  • Family: Euglenaceae
  • Genus: Euglena
  • Species: gracilis

These freshwater, motile unicellular algae have two anterior flagella of which only one emerges from flagellar reservoir. They are both autotroph and heterotroph in nature and consume smaller microbes like amoeba through phagocytosis. They reproduce asexually through longitudinal mitotic cell division.

unicellular algae examples
Fig: “Euglena gracilis- Protiste (végétal)” by Philippe Garcelon is licensed under CC BY 2.0. Copy text

Chrysophyta: Golden-brown and yellow-green algae; Diatoms

They are flagellated, unicellular autotrophs with mitochondria. They have chlorophyll a and c1/c2, and carotenoid fucoxanthin. Two anteriorly attached flagella of uneven length are present.

Mallomonas elegans

  • Phylum: Chrysophyta
  • Class: Chrysophyceae
  • Order: Ochromonadales
  • Family: Synuraceae
  • Genus: Mallomonas
  • Species: elegans

These freshwater unicellular algae are covered by intricate silica scales and bristles. They are golden-brown in color.

unicellular algae examples
Fig: “Mallomonas sp.” by greenmarlin is licensed under CC BY-SA 2.0. Copy text

Cyclotella meneghiniana-

  • Phylum: Ochrophyta
  • Class: Bacillariophyceae
  • Subclass: Coscinodiscophycidae
  • Order: Thalassiosirales
  • Family: Stephanodiscaceae
  • Genus: Cyclotella
  • Species: meneghiniana

These marine water algae are found in oligotrophic environments. They have the largest genome among all the diatoms, 171 Mb in size. They proliferate through asexual reproduction which results in decreasing cellular size.

Pyrrophyta: Dinoflagellates

Unicellular, autotrophic phytoplankton which are mostly marine but some can be found in freshwater environment. They act as a primary food source for almost every aquatic food chain.

Noctiluca scintillans-

  • Phylum: Pyrrophycophyta
  • Class: Dinophyceae
  • Order: Noctilucales
  • Family: Noctilucaceae
  • Genus: Noctiluca
  • Species: scintillans

These free-living, marine dinoflagellates can be found throughout the world and have bioluminescence properties. They cause toxic algal bloom, known as red tide which causes harm to fishes and corals.

unicellular algae examples
Fig: “File:Noctiluca scintillans unica.jpg” by Maria Antónia Sampayo, Instituto de Oceanografia, Faculdade Ciências da Universidade de Lisboa is licensed under CC BY 3.0. Copy text

Pyrodinium bahamense-

  • Phylum: Pyrrophycophyta
  • Class: Dinophyceae
  • Order: Gonyaulacales
  • Family: Goniodomataceae
  • Genus: Pyrodinium
  • Species: bahamense

These autotrophic, marine dinoflagellates are generally found in Atlantic Ocean. They produce bioluminescence and also paralytic toxin. They possess chlorophyll a & c and peridinin.

Charophyta: Stoneworts or Brittleworts

These motile green algae are commonly found in fresh to brackish water. They have two flagella attached in a lateral position. They reproduce sexually by forming a dominant zygote which eventually germinates by meiotic division. The evolutionary line of charophyta later evolved into land plants.

Cylindrocystis brebissonii-

  • Phylum: Charophyta
  • Class: Conjugatophyta
  • Order: Zygnematales
  • Family: Mesotaeniaceae
  • Genus: Cylindrocystis
  • Species: brebissonii

These autotrophic green algae have a cylindrical body with asteroid shaped chlorophyll. They are generally found in freshwater or terrestrial habitats.

Euastrum humerosum-

  • Phylum: Charophyta
  • Class: Conjugatophyta
  • Order: Desmidiales
  • Family: Desmidiaceae
  • Genus: Euastrum
  • Species: humerosum

These are freshwater algae. They have a pyramidal outline of their cell, with deep invagination of the median apical incurvation, dividing the cell into apical, lateral and basal lobes.

unicellular algae examples
Fig: “Euastrum sp – Algue verte” by Philippe Garcelon is licensed under CC BY 2.0. Copy text

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