Brown Algae

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Brown Algae Description

A large number of multicellular algae, along with several seaweeds found in colder waters throughout the Northern Hemisphere, are the brown algae (singular: algae) representing the class Phaeophyceae. In marine environments, several brown algae live, where they play a significant role both as food and as a possible habitat. Brown algae examples may include kelp, ectocarpales, dictyotales, fucales etc. 

According to brown algae description, brown algae examples include, Macrocystis, a kelp of the Laminariales order, can reach a maximum of 60 m (200 ft) as well as shape significant underwater kelp forests. There is a high degree of biodiversity in kelp forests like these. An example of the same is Sargassum, which produces special floating seaweed mats which functions as habitats for several species in the tropical waters of the Sargasso Sea.

Most brown algae typically grow across rocky seashores, including the members of the order Fucales. Few members of the class, including kelps, are being used as food by humans.

Worldwide, between 1,500 and 2,000 species of brown algae are recognized. Due to their commercial importance, several plants, including Ascophyllum nodosum, are becoming subjects of comprehensive investigation in their own right. They also, by carbon fixation, have environmental significance.

Morphology of Brown Algae

In a large variety of sizes and shapes, occur brown algae. As tiny, feathery tufts of threadlike cells barely more than a few centimetres (a few inches) long, the smallest members of the group grow. In their life cycle, certain species get to a phase that consists of just a few cells, rendering the whole algae microscopic. Some brown algae classes, on the other hand, expand to much larger sizes.

The most noticeable algae in their environments are mostly rockweeds as well as leathery kelps. Kelps can vary in size from the 60-centimetre-tall (2 ft) Postelsia sea palm to the giant kelp Macrocystis pyrifera, the greatest of all algae that reaches more than 50 m long. 

The brown algae vary in shape from tiny crusts or cushions to leafy free-floating mats produced by the Sargassum species. As in Ectocarpus, they can comprise sensitive felt-like cell strands or, as in Padina, which are 30-centimeter-long (1 ft) with flattened branches like a fan.

Growth of Brown Algae

  • The fastest and largest growing seaweed is brown algae. Macrocystic fronds can grow quite large enough as 50 cm (20 in) every day, and in a single day, the stripes might expand to 6 cm (2.4 in).

  • Growth happens at the edges of structures in many of these brown algae as a consequence of divisions in a particular apical cell and in a line of these cells in cellular species that are single.

  • As these apical cells begin to divide, all the tissues of the algae grow into the new cells that it creates. When the apical cell divides to create two fresh apical cells, branchings and several other lateral structures emerge. 

  • However, by diffused, unlocalized development of new cells which can appear anywhere else on the thallus, several groups (such as Ectocarpus) develop.

Life Cycle

Many brown algae undergo sexual reproduction by sporic meiosis with the exception of the Fucales. The algae get through the different sporophyte (diploid) and gametophyte (haploid) phases between generations. Although some species of brown algae have identical diploid and haploid stages, the sporophyte stage is perhaps the most noticeable of the two.

Free-floating varieties of brown algae also do not experience sexual reproduction until they have been bound to the substrate. Male and female gametophytes are the haploid generation. Egg cell fertilization differs amongst brown algae species and can be isogamous, oogamous, or anisogamous. In the water with eggs as well as motile sperm, or within the oogonium itself, fertilization may occur.

Through the manufacture of motile diploid zoospores, some brown algae species may also achieve asexual reproduction. In the plurilocular sporangia, these zoospores develop and therefore can mature instantly into the sporophyte process.


  • Brown algae have suited to a large range of ecological marine niches, such as the entire intertidal zone, the rock pools, tidal splash zone, and comparatively deep sea close to the shore. 

  • They are an essential element of certain habitats of brackish water, and also have inhabited freshwater on six recorded occasions at most.

  • Intertidal or upper littoral include a significant number of Phaeophyceae, and they are mostly cool and cold water species that gain nutrients through cold water currents and inflows from the land; Sargassum is a notable exception to this generalization.

  • Brown algae are almost entirely asexual, emerging in brackish waters.

Brown Algae Importance and Uses

Economic Importance of Brown Algae:

  • A variety of edible seaweeds contain brown algae. In their cell walls, all brown algae contain alginic acid (algin brown algae), brown algae extract is commercially extracted and being utilized as an industrial oxidizing agent in food and for many other uses. 

  • In lithium-ion batteries, one of these items is used. As a stable part of a battery anode, Alginic Acid (algin brown algae) has been used.

  • Alginic acid could be used in aquaculture as well. Alginic acid, for instance, strengthens the immune system of the rainbow trout. When provided with a diet of alginic acid, the younger fish are able to persist much more.

  • Also one of the economic importance of brown algae is it repairs a good percentage of the earth's carbon dioxide annually by photosynthesis, like kelp beds. And a significant quantity of carbon dioxide can be contained in them, which could help us combat climate change. 

  • It has been shown that Sargachromanol G, an extract of Sargassum siliquastrum, provides anti-inflammatory effects.

FAQ (Frequently Asked Questions)

Q1. Name the Pigment which is used by Brown Algae for the Process of Photosynthesis.

Ans. Fucoxanthin is the pigment that brown algae use for the process of photosynthesis. While brown algae produce chlorophyll, the photosynthetic pigment fucoxanthin is predominantly found in them, reflecting yellow light. Fucoxanthin is called an accessory pigment that absorbs the heat and then transfers this energy for processing on to chlorophyll.

Q2. What is the Colour Light Absorbed by the Brown Algae Pigments?

Ans. The blue-green light energy can be absorbed by brown algae pigments and converted to green chlorophyll for the process of photosynthesis (can be defined as a process whereby algae undergoes the manufacturing of food by making use of carbon dioxide, water and light energy).