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Sargassum is a brown seaweed that grows in seas and oceans. It belongs to the class Brown Algae (Phaeophyceae).
- Sargassum is commonly known as sea holly and gulfweed.
- It is found free-floating over the seas and oceans.
- About 150 species of seaweed are found attached to the rocks along the coasts of the seas and oceans.
Out of 150 species, 16 species of seaweed are found in India. The common species of sargassum seaweed found in India are S. tennerimum, S. cinereum, S. wightii, and S. ilicifolium.
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| Table of Content |
Key Terms: Sargassum, Seaweed, Brown Algae, Sargasso Island, Gulfweed, Phlorotannins, Sea, Species
Sargassum Seaweed
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Sargassum is a seaweed that is also known as gulfweed or sea holly.
- Sargassum appears like branched leafy appendages and round berry-like structures.
- There are around 150 species of sargassum that are generally attached to the rocks along the coasts.
- Other species float freely in the open seas and oceans.
- The large quantities of floating sargassum on beaches create negative impacts on tourists.
- However, they do not create any health risks.
- On losing its buoyancy, it sinks and reaches the seafloor.
- It then decomposes and provides carbon to the fishes and other species in the deep sea.
- Thus, it plays an integral role in the deep-sea food chain.
Sargassum
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| Relevant Concepts | ||
|---|---|---|
| Marine Biology | Phycology | Algal Bloom |
| Green Algae | Red Algae | Difference Between Algae and Bryophytes |
Taxonomic Classification of Sargassum
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Taxonomic level of classification of Sargassum is given below. According to taxonomic classification, sargassum is classified into 7 taxonomic levels.
| Taxonomic Classification of Sargassum | |
|---|---|
| Kingdom | Chromista |
| Phylum | Phaeophyta |
| Class | Phaeophyceae |
| Order | Fucales |
| Family | Sargassaceae |
| Genus | Sargassum |
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Structure of Sargassum
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Sargassum has a branched leafy and round-berry-like structure. The plant body of the sargassum is dark green (brown) in color and consists of a stipe, holdfast, and frond.
- This algae ideally grow to a length of several meters.
- The fronds of sargassum are numerous, they are small and leaflike having a toothed edge.
- The stipes consist of the main axis and lateral branches.
- The algae are attached to the layer by holdfast which is discoid and broad in structure.
- Matured algae are free-floating over water bodies.
- The main axis of stipes has 2 types of lateral branches namely primary and secondary laterals.
- The primary lateral grows from the main axis and has unlimited growth.
- While the secondary lateral arises from the primary laterals and has limited growth.
- Some lateral branches are repeatedly branched over themselves and are referred to as fertile branches.
- These fertile branches are known as receptacles.
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Characteristics of Sargassum
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The characteristics of Sargassum are as follows:
- All dried seaweed has a phenol-level composition of up to 20%.
- Seaweeds are well known for their rich content of bioactive compounds.
- The extracts of sargassum exhibit antimicrobial functions on pathogens.
- Sargassum is a rich source of potassium, iodine, and magnesium. Also, it is rich in sources like dietary fiber, polyphenols, and antioxidants.
- Sargassum is the richest source of protein even more than that in the yolk of an egg.
- S. tenerrimum, a specie of sargassum is made up of a gel enhancer.
- Secondary metabolites and phenolic compounds are found in the higher level of brown algae, named phlorotannins.
Uses of Sargassum
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The various applications of Sargassum are mentioned below:
- Sargassum is commonly used as a dietary supplement that helps in managing some health conditions.
- For centuries, sargassum is used in traditional medicines for the treatment purposes of various health conditions and diseases.
- Sargassum is used as a natural food preservative.
- It is used in some skin care products like shampoos, shower gels, toothpaste, skin care creams, etc.
- The components abstract from sargassum kelp are commonly used for the food proteins such as myofibrillar protein.
Sargassum Bloom
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Sargassum Reproduction
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Sargassum reproduces through vegetative reproduction and sexual reproduction. There is no mode of asexual reproduction in sargassum.
- Vegetative Reproduction
- Sexual Reproduction
Vegetative Reproduction
- S. natans and S. fluitans are the two species of Sargassum that are holopelagic.
- Holopelagic means these species do not attach to the seafloor.
- They reproduce vegetatively through fragmentation.
Sexual Reproduction
- Sexual reproduction mode in sargassum is of the oogamous type.
- Both the oogonium and antheridium hold up on different conceptacles.
- The conceptacles have multiple multilayered walls that contain chromatophores.
Ecology of Sargassum
Sargassum islands are developed in the Sargasso sea which serves as a habitat for the development of the ecosystem.
- Since a sea does not have land boundaries, hence the sargassum mats are used as an ecosystem of the endemic species.
- Sargassum islands are home to many aquatic species that duplicate the algae by camouflaging themselves.
- More than 100 different endemic species reside on such mats.
- About 81 species of fish reside on these islands also they use them in their life cycle.
- Sea turtles that live on such sargassum mats utilize their shelters and foods until they are mature enough to reside by themselves.
- American eel, American conger eel, and European eel migrate to the Sargasso sea to lay eggs and spawn.
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| Related Topics | ||
|---|---|---|
| Mycology | Pelagic Zone | Detritus Food Chain |
| Reproduction in Plants | Energy Flow in Ecosystem | Vegetative Propagation in Plants |
Things to Remember
- Sargassum is a brown seaweed that belongs to the Brown Algae (Phaeophyceae) class.
- It is found free-floating in seas and oceans.
- Sargassum can be reproduced through two modes of reproduction namely Vegetative reproduction and Sexual reproduction.
- Sargassum is considered to be the richest source of protein available in nature.
- S. muticum is the most notable species of Sargassum.
- Sargassum is essential habitat for many water bodies like fishes, sea turtles, and eels.
- Sargassum is used in medicines that help in the treatment of diseases and various critical health conditions.
Previous Years’ Questions
- Which of the following groups of algae produces algin… (AIIMS 2015)
- Which one of the following statements is wrong… (NEET 2016)
- Aquatic Horsetail is…
- Algmic acid is present in the cell wall of…
- Which of the following pairs is of unicellular algae… (NEET 2020)
- Which of the following groups of algae belongs to class… (KEAM)
- An example of an artificial system of classification is… (KEAM)
- Algae are useful because they… (AIIMS 2002)
- All algae have… (CBSE CLASS XII)
- Which group includes protozoa, protistan algae, and… (OJEE 2013)
Sample Questions
Ques. How is sargassum seaweed useful? (3 Marks)
Ans. Sargassum seaweed is considered the richest source of protein, cellulose, carotenoids, glutamic acids, and aspartic acid. It is rich in phenol composition. Some polysaccharides found in sargassum kelp help in controlling blood pressure and blood sugar. Sargassum seaweed has high antioxidant and antibacterial properties. It is a habitat and provides food for various marine features like fish, turtles, eel, crabs, and shrimps.
Ques. Explain the life cycle of sargassum. (3 Marks)
Ans. The life cycle of sargassum is of diplontic type (the main stage is diploid) and there is no alteration of generation.
- The thallus of the sargassum is diploid sporophytic.
- It produces diploid antheridia (male sex organ) and oogonia (female sex organ).
- Antheridia and oogonia undergo reduction division and form haploid antherozoid and oogonial nuclei respectively.
- The gametes are haploid-structured in the life cycle.
- After fertilization, a diploid zygote is produced which further divides to form a diploid sporophytic thallus.
Ques. Explain sexual reproduction in Sargassum. (3 Marks)
Ans. The male organ of the sargassum is called antheridia and the female oogonia.
- Male and female sex organs develop in a cavity called a conceptacle.
- The antherozoids are released in water bodies while the oogonia remain attached to the conceptacles.
- Antherozoids surround the oogonium and stick with the oogonial wall by the anterior flagellum.
- Both sex nuclei fuse together to form a zygote.
- The zygote divides itself by transverse division into lower and upper cells.
- The upper cell further divides into diploids known as sargassum.
Ques. Explain the vegetative reproduction in sargassum. (3 Marks)
Ans. Sargassum can be reproduced by vegetative fragmentation. The thallus of sargassum breaks into fragments due to death or mechanical injury and decay of older plants. Species like S. natans and S.hystrix grows in a sargasso sea and are infertile because they do not form any reproductive structures. These species undergo fragmentation and multiply themselves into smaller species.
Ques. What are the differences between primary lateral and secondary lateral? (3 Marks)
Ans. The difference between primary lateral and secondary lateral is as follows:
| Primary Laterals | Secondary Laterals |
|---|---|
| The primary lateral grows from the main axis. | The secondary lateral arises from the primary lateral |
| Primary laterals have unlimited growth | Secondary laterals have limited growth |
| Primary lateral are produced from promeristem and are responsible for the primary growth of sargassum. | Secondary lateral is produced from primary tissues and is responsible for secondary growth. |
Ques. How does the sargassum seaweed develop? (3 Marks)
Ans. The sargassum seaweed is developed from fertilized eggs that bring into a free-floating larva. The larva then eventually settles down on the sea (or ocean) floor where it grows into a small plant. Thus the plant produced then produces fruits and flowers that release eggs which further settle down on the floor and grow into a new small plant. This life cycle continues and the eggs are grown up into new plants.
Ques. How sargassum is useful for the ecology of endemic species? Explain with the help of examples. (5 Marks)
Ans. The sargassum islands get developed in the Sargasso sea which serves as a habitat for the development of the ecosystem. Since the sea does not have land boundaries hence the sargassum mats are used as an ecosystem of the endemic species. The sargassum islands are home to many aquatic species that duplicate the algae by camouflaging themselves.
The examples are:
- Fishes that reside on these islands use them in their life cycle. About 81 different species of fish live on such islands.
- Sea turtles utilize their shelters and foods on such sargassum mats until they are mature enough to reside somewhere else.
Ques. What is Stripe in Sargassum? (3 Marks)
Ans. Stipe is a part of the sargassum made up of the main axis and lateral branches. Stipe work as a middleman between the blade and the holdfast. The main function of the stipe is to transport nutrients within the sargassum. Holdfast is abroad and discoid-like structured root that attaches the thallus to the substrate. Holdfast support sargassum and comfort down the algae to the floor.
Ques. Why is Sargassum wiped out from the sargassum islands? (3 Marks)
Ans. The sargassum species are wiped out from the sargassum islands due to increasing human activities such as overfishing, boat traffic, trash, and water pollution. It is concluded from the research that due to spontaneous climate change there is a rise in water temperature and an increase in the amount of nitrogen-laden fertilizer and sewages that cause the nourishing of sargassum.
Ques. Is it safe for humans to swim in water occupied by sargassum? (3 Marks)
Ans. Before entering the water, it is important to check the state of the sargassum. If the sargassum is alive, it is not hazardous for humans. In the alive state, water is safe to use and swim. But if it reached the land boundaries and dies, it starts releasing hydrogen sulfide gas. This may cause irritation on human skin if interacted with. The hydrogen sulfide gas develops a smell of rotten eggs in water.
Breathing such toxic gases can cause respiratory issues in humans. On interacting with water polluted with dead sargassum, humans will experience shortness of breath, vertigo, headache, dizziness, and other serious complications.
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