Are Algae Multicellular: 7 Facts Most Beginner’s Don’t Know

This article would focus on establishing ideas regarding “are algae multicellular” along with seven different facts associated with algae. 

Algae are microorganisms which are photosynthetic in nature and live in water to grow hydroponically. These organisms are capable of assimilating carbon mixotrophically as well as heterotrophically. Algae are established as the representation of ancient plants and help in composing the evolutionary lineages of various photoautotrophic organisms. 

Are most algae multicellular?

Algae are both unicellular as well as multicellular in nature. There are several large-sized Algae which have millions of cells. There are macroscopic algae which even have groups of cells which are specialised for specific sets of functions within the organisms. 

The cells engage in performing functions like transport, photosynthesis, reproduction or anchorage and these specialisation helps in establishing the link with complexity and evolution among organisms. 

Which algae is unicellular?

Diatoms and the Golden-brown algae are identified as the most abundant types in representing the unicellular algae. These types contribute to more than 100,000 differentiating species as unicellular algae and are found in fresh as well as salt water. 

Comparatively, the species of diatoms are more than the golden-brown type. There are other types as well which have unicellular algae, like Dinoflagellates and Euglenophyta. Few examples of unicellular algae would be Chlorella and Chlamydomonas. 

Multicellular algae examples

The three types of algae which are multicellular in nature. The first one is  the brown algae, also known as phaeophyta. Second one is the green algae, also known as chlorophyta. Third one is the red algae, also known as rhodophyta. 

There are specialised tissues found in multicellular algae but they lack true roots or stems like the higher complex plants. Examples of multicellular algae would be the giant kelp, Spirogyra and ulothrix. 

Are green algae multicellular?

Green algae are mostly multicellular in nature. The unicellular green algae species engage in forming colonies. The green algae have a diverse taxonomy and have various multicellular phenotypes which include forms like filamentous, colonial and parenchymatous. 

Green algae is identified as the member under the division Chlorophyta which has around 12000 species and has the photosynthetic pigments like chlorophyll a, chlorophyll b, carotene and more. The proportions of these pigments are similar to the higher complex plants. 

Examples of unicellular green algae would be Chlamydomonous and desmids. In terms of multicellular green algae, the examples would be Spirogyra in filamentous, Volvox in colonial and Caulerpa in parenchymatous. 

Are red algae multicellular?

Primarily, red algae are multicellular in nature, but there are few unicellular forms of red Algae as well. This type of algae mostly lacks flagella and range from microscopic protists which are unicellular to multicellular large forms of seaweed form.  

Red Algae are exclusively marine in nature and has the ability to reproduce sexually. These tend to have rigid cell walls which contain carrageenan or agar. In the evolution of eukaryotes, red algae are identified as the most ancient lineage for multicellular organisms. 

One example of unicellular red algae would be Cyanidioschyzon morolae and is considered as the simplest organism with only 4775 protein coding genes within the nucleus. Some examples of multicellular red algae would be Schmitzia hiscockiana, Chondrus crispus (Irish moss) and Mastocarpus stellatus

Are filamentous algae multicellular?

Filamentous algae are mostly multicellular in nature. These have specialised tissues built of multiple cells that can engage in a number of other activities like transport, photosynthesis, reproduction or anchorage. 

One such example of filamentous algae would be Spirogyra, which is under green algae. It is floating and is found mostly in the freshwater. It consists of spiral chloroplasts and have unbranched thin chains of similar cylindrical cells. It is covered with a mucilaginous sheath and consumed by humans in different parts of the world.  

Are golden algae multicellular?

Most of the golden algae are unicellular, that is, they are composed of a single cell. These are biflagellates, where the lagae has two specialised flagella. This type of algae has high concentrations of fucoxanthin and engages in using oil droplets as food reserves. 

Golden algae are also identified as chrysophytes and are mostly found in the freshwater. It has the pigment fucoxanthin and most of them can engage in producing photosynthesis. It is this pigment that gives the algae olive-green colour. 

It covers almost 1200 species but the most common example is Prymnesium parvum which occurs largely across the globe. It has the ability to produce toxic algal blooms and hence, can eliminate other aquatic species like fishes. Other examples would include, desmids and Chrysosphaera. 


In conclusion to “are algae multicellular?”, it can be established that algae can be both, either unicellular or multicellular. In unicellular, the most common types are diatoms and golden-brown algae. In multicellular, the most common types are red algae, green algae and brown algae. 

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