Algae | Classification, Characteristics & Examples

By | April 28, 2019

Algae Definition

Algae are the basically gigantic, miscellaneous assemblage of Photosynthetic eukaryotic organisms. They might be the unicellular cell, multicellular or may even live in the colonial form.


Algae Characteristics

  1. They are unicellular or multicellular Eukaryotic organisms.
  2. Its body lacks specialized structures like Roots, leaves, and Stems.
  3. Their body contains Chlorophyll and photosynthetic pigments which help to perform Photosynthesis.
  4. In the Plankton Unicellular Algae are found enormously.
  5. Phytoplankton also comprised of the vast number of Unicellular Algal species. Phytoplankton is basically free‐floating microorganism’s population.
  6. They also present in the moist soil and also present on the surface of Rocks and stones.
  7. They can also live with Fungi in the Lichens and give the example of Mycorrhizal Association.
  8. Whittaker classified fungi in seven divisions. Out of these classifications, five are considered in the Kingdom Protista. Rests of two groups of Fungi are considered in the kingdom Plantae.
  9. Algal Cells have eukaryotic properties while some algal species have Flagella.
  10. Flagella are arranged in the special microtubules pattern the pattern is “9‐plus‐2” of Microtubules.
  11. Algal cells have specialized Nucleus. Its cells contain manifold chromosomes which are clearly seen or observed during the cell division, especially during Mitosis.
  12. Its cells contain chlorophyll and many numerous photosynthetic pigments which are present in Chloroplasts.
  13. Many algae are Photoautotrophic in nature and make their own food by the process of Photosynthesis.
  14. Some Algal species are Chemo-heterotrophic in nature and get there energy by the chemical reactions which take place in the decomposition of organic matter.
  15. Various Algal species are Saprobes, and few are Parasites in nature.
  16. They reproduce by Asexual and Sexual reproduction.
  17. During the Asexual reproduction crumbling of Algal colonial, or by spore development.
  18. During the reproduction process by the process of Mitosis, spores are formed.
  19. In few Algal species, Binary fission also occurs just like as in the Bacterial species.
  20. During sexual reproduction, well differentiate sex cells formed later on they mingle and Diploid zygote is produced which contain two chromosomal sets.
  21. The zygote, later on, converts into sexual spores. When they get a sympathetic environment spores will germinate.
  22. After germination, development starts haploid organism formed which have a single set of chromosomes.
  23. They have Alternation of Generations during the reproduction.

Algae Structure:


Algae Classification:


Common Name

Body structure

Characteristic Features



Green Algae

  • Unicellular,
  • Colonial,
  • Filamentous,
  • Multicellular
  • Chloroplasts bounded by two membranes.
  • Photosynthetic pigments present.
  • Chlorophyll a and b present


Red Algae

  •  Multicellular body
  • Photosynthetic pigments present.
  • Chlorophylls  and d, present.
  • Phycobilins and Beta-Carotene also present.
  • These are light-capturing molecules.



  •  Unicellular
  • Chloroplasts bounded by three membranes.
  • Present in freshwater.


Brown Algae

  •  Multicellular
  • Live in the Marine environment
  • the Complex type of marine Algae


Golden algae

  • Unicellular,
  • Filamentous
  • A large group of Algae
  • Found mostly in freshwater.
  • Free swimming Algae.



  •  Unicellular
  • Unicellular or sometime colonial coccoid
  • Non-motile.
  • None are free-living flagellates.



  • Unicellular
  • Two naked flagella present
  • Few species have delicate hairs on the flagella.
  • Do not have to swell at the flagellar base.



  • Unicellular
  • Eukaryotic organisms.
  • Contain two whip-like tails called flagella.
  • Flagella used for movement.
  •  Found in both marine and freshwater environments.

Algae Facts

  1. They can almost grow anywhere where water and sunlight are present. They usually found in both marine and terrestrial environment.
  2. Like the plants, they are the Photosynthetic organisms.
  3. Evenly its one group called Green Algae is classified in to plant group due to maximum resembling characters with the plants.
  4. They, being the photosynthetic group, harvest a huge amount of the oxygen on Planet.
  5. They are present enormously in the ocean and prepare food by the process of photosynthesis.
  6. In addition to Sunlight Algae also necessitate a huge assortment of nutrients in addition to Sunlight.
  7. Algae experience restarted or stunted growth if they get favorable conditions but nutrients are present in small quantity.
  8. Due to the above-mentioned condition, Algal Blooms raised. In which a vast amount of Algal Blooms raised at the same time.
  9. In this condition, they speedily become impenetrable and start assassination of many Algal species in the internal side of the bloom.
  10. Bacteria and many other micro-organisms move into the Algal Bloom and feedstuff on the dead bodies and diminishing the oxygen of water.
  11. Due to this inside the Ocean “Dead Zone” is created which can be poisonous of fatal for many other species.
  12. During this condition, some algae produce toxic compounds which are harmful and fatal for wildlife and human population.

Green Algae:

It is the most diverse Algal group is Green Algae. On the basis of the variation of habitat, its 7000 species are identified by Biologist. It is considered a Paraphyletic Group. They consist of two types of Chlorophyll for light capturing during the process of photosynthesis just like plants. But they are found in Aquatic environment.


How does Algae Reproduce?

They replicate by Sexual and Asexual mean of Reproduction. During the Asexual reproduction fragments of the Algal body are formed. During this process cells or in short fragments did not combine their genetic material. Due to this which algal species are formed complete algae mirror of its parents. In the case of higher Algae, reproduction also takes place by spores.

Sexual reproduction typically comprises of meiosis using genetic material from two different parent cells. Different environmental events influence and regulate sexual reproduction.

During sexual reproduction. Specialized sex cells fused and the zygote is formed. During this cycle, the first stage has one chromosomal set that is known as Haploid stage. The second phase is diploid which have two chromosomal sets.


Which Algae types are Harmful?

Only a few algals species are harmful. Some species, such as the

  • Dinoflagellate Alexandriumtamarense
  • Diatom Pseudo-nitzschiaaustralis


They manufacture persuasive toxins.

  • Chaetocerosspecies has a spine with saw-like edges. When they are eaten up by fish which can cottage in fish gill tissues, cause irritation, over mucous production, and eventually cause death.


You May Also Like:  Fungi | Definition, Characteristics & Types

Algae Examples:

Few examples are given below:

  • Chlamydomonas,
  • Chara
  • Dictyota,
  • Laminaria,
  • Sargassum
  • Porphyra,
  • Gracilaria,
  • Nostoc
  • Fucus
  • Diatoms
  • Spirogyra
  • Microcystis
  • Duckweed
  • Pandorina