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What Is The Definition Of Algae In Biology

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Economic Products Obtained From Algae

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The most important economic products obtained from algae are associated with brown and red seaweeds, which can be utilized as food for people, and as resources for the manufacturing of industrial products. These seaweeds are mostly harvested from the wild, although increasing attention is being paid to the cultivation of large algae.

Some species of algae can be directly eaten by humans, and in eastern Asia they can be especially popular, with various species used as foods. An especially common food is the red alga known as nori in Japan and as laver in western Europe , which has long been eaten by coastal peoples of China and Japan. This alga is often used as a wrapper for other foods, such as rice or plums, or it may be cooked into a clear soup. Nori has been cultivated for centuries in eastern Asia. Another alga known as dulse or sea kale is consumed dried or cooked into various stews or soups. Other commonly eaten seaweeds include the sea lettuce , and murlins or edible kelp .

Potentially, seaweeds are quite nutritious foods, because about 50% of their weight occurs as carbohydrates, with smaller concentrations of proteins and fats, and diverse micronutrients, including iodine. In practice, however, seaweeds are not very nutritious foods for humans, because we do not have the enzymes necessary to metabolize the most abundant of the complex, algal carbohydrates.

History Of Classification Of Algae

Although Carolus Linnaeus included algae along with lichens in his 25th class Cryptogamia, he did not elaborate further on the classification of algae.

Jean Pierre Étienne Vaucher was perhaps the first to propose a system of classification of algae, and he recognized three groups, Conferves, Ulves, and Tremelles. While Johann Heinrich Friedrich Link classified algae on the basis of the colour of the pigment and structure, William Henry Harvey proposed a system of classification on the basis of the habitat and the pigment. J. G. Agardh divided algae into six orders: Diatomaceae, Nostochineae, Confervoideae, Ulvaceae, Floriadeae and Fucoideae. Around 1880, algae along with fungi were grouped under Thallophyta, a division created by Eichler . Encouraged by this, Adolf Engler and Karl A. E. Prantl proposed a revised scheme of classification of algae and included fungi in algae as they were of opinion that fungi have been derived from algae. The scheme proposed by Engler and Prantl is summarised as follows:

Gephyrocapsa oceanicaHistoria Fucorum

Linnaeus, in Species Plantarum , the starting point for modern botanical nomenclature, recognized 14 genera of algae, of which only four are currently considered among algae. In Systema Naturae, Linnaeus described the genera Volvox and Corallina, and a species of Acetabularia , among the animals.

Algal Characteristics Basic To Primary Classification

The primary classification of algae is based on certain morphological features. The chief among these are pigment constitution of the cell, chemical nature of stored food materials, kind, number, point of insertion and relative length of the flagella on the motile cell, chemical composition of cell wall and presence or absence of a definitely organized nucleus in the cell or any other significant details of cell structure.

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Death Of Aquatic Animals And Plants

With the increase in concentration of algae in the water body, algae completely cover the water body from the top. They form a thick layer of algae on the top and which stops the sunlight from reaching the bottom of the water body.

As many plants and organisms are present at the lower levels of water and at the bottom also, they dont get proper sunlight due to the layer of the thick formation of algae. Which affects their life cycle adversely. Due to the shortage of sunlight at the bottom many organisms cant do photosynthesis properly and hence left with less food to survive upon.

Definition Of The Term Algae

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Algae represent a highly diverse consortium of ancient plants comprising different evolutionary lineages of mostly photoautotrophic organisms. The different groups of algae are of polyphyletic origin and epitomize the majority of existing divisions of plants. Algae are thallophytic their vegetative body is not organized in roots and leafy stems like that of the kormophytes. Many algae are living in solitary cells, colonies, filaments, or primitive vegetation bodies and do not have a vascular system. In contrast to the phanerogams , the algae are cryptogams that propagate by concealed or hidden reproductive strategies. Following a conception of subdivision of living organisms into five kingdoms , the prokaryotic algae are placed in the Monera and the eukaryotic algae in the Protoctista. Hence, the algae do not belong to the kingdom of Plantae. Nevertheless, it is widely accepted to interpret algae as lower plants in distinction to the vascular higher plants.

Thomas N. Taylor, … Michael Krings, in, 2009

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What Are Harmful Blue

Blue-green algae, technically known as cyanobacteria, are microscopic organisms that are naturally present in lakes and streams. Under certain conditions, blue-green algae can become abundant in warm, shallow, undisturbed, nutrient-rich surface waters that receive a lot of sunlight. When this occurs, blue-green algae can form blooms that discolor the water, or produce floating mats or scums on the waters surface. Blooms can also form on rocks, along the shoreline, and at the bottom of a waterbody. These are called benthic blooms. It might be a harmful blue-green algae bloom if the water is blue-green, green, yellow, white, brown, purple, or red, has a paint-like appearance, or if there is scum on the water surface.

What Does It Eat

Golden alga is part of the plankton community that forms the base of the food chain in aquatic environments. Single-celled algae are among the phytoplankton , which are eaten by zooplankton . Zooplankton are eaten in turn by aquatic insects and small fish, which provide food for bigger fish. It sounds simple, but in reality the food chain is more like a web, with complex interactions at the low end. Different species of plankton compete for food and often eat each other.

As a plant containing chlorophyll, golden alga can make its own food using sunlight and inorganic nutrients found in the water. However, it’s also capable of preying on other organisms. Under certain kinds of stress, golden alga cells release at chemical compounds that combine with minerals in the water to make toxins. These toxins appear to serve several purposes:

  • Slow down bacteria and other algae, making it easier for the golden alga to catch and eat them.
  • Destroy cells of some organisms, causing them to release dissolved organic matter which then becomes food for the golden alga.
  • Repel some of the zooplankton that graze on golden alga.
  • Inhibit growth of other algae species.

These survival characteristics appear to provide golden alga with the ability to out-compete other organisms and form high-density blooms that can significantly disrupt aquatic ecosystems.

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The Chemical Composition Of Algae

Algae are Composed of Two Types of Cells: eukaryotic or prokaryotic cells. These are cells with nuclei and organelles. The functional systems of algae are plastids, which are bodies with chlorophyll and carry out photosynthesis. Some have only Chlorophyll A, some A, and B, A and C, etc. the primary composition of algae is made up of proteins, carbohydrates, fats, nucleic acids, in varying proportions. All types of algae found completely comprise of the following, in varying proportions: Proteins, Carbohydrates, Fats and Nucleic Acids. While the percentages vary with the type of algae, types of algae are there, some of them comprising up to 40% of their overall mass by fatty acids. This fatty acid from the algae can be extracted and converted into biodiesel. Algal oil is very high in unsaturated fatty acids which include Arachidonic acid , Eicosapentaenoic acid , Docosahexaenoic acid , Gamma-linolenic acid , Linoleic acid , etc.

Economic And Ecological Importance

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Algae are the base of the aquatic . Humans also eat many types of algae. The marine algae nori and kelp have been harvested in China for over two thousand years. Spirulina, a that is rich in protein and vitamin B, is harvested from in Africa. The photosynthesis done by algae is very important to the biosphere because it reduces the amount of and increases the amount of oxygen in the atmosphere.

Some types of algae can cause environmental problems such as red tides and fishy-tasting water. These problems are usually caused by the excessive release of nutrients from farms, sewage, and other human activities. The outbreak of the nerve-toxin-producing Pfiesteria on the Atlantic coast, for example, has been linked to overflowing sewage lagoons.

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Conclusions And Future Trends

Algae, which are low-energy foods, contain a wide variety of compounds with useful nutritional and technological properties, and of bioactive sustances with potential multi-functional properties when incorporated into the matrixes of foods and beverages. Compared to the inclusion of compounds isolated from algae, the use of whole algae in food and beverage production is a means of simultaneously including different components in a way that does not involve the laborious, expensive and environmentally unfriendly extraction and purification processes which are required when these components are used individually.

A wide variety of algae have been used for different purposes in food and beverage formulations. When added to these products, algae offer interesting technological, nutritional and health benefits, but they also present some sensory drawbacks relating to the characteristics of the product and the algae used . For example, the addition of these algae to muscle-based products opens up interesting new prospects for the use of algae in the formulation of healthier meat products, including the possibility of overcoming technological problems associated with low-salt products.

M. García-Garibay, … E. Bárzana, in, 2014

Architects Of Earth’s Atmosphere

Cyanobacteria are aquatic and , that is, they live in the water, and can manufacture their own food. Because they are bacteria, they are quite small and usually unicellular, though they often grow in colonies large enough to see. They have the distinction of being the oldest known fossils, more than 3.5 billion years old, in fact! It may surprise you then to know that the cyanobacteria are still around they are one of the largest and most important groups of bacteriaon earth.

Many Proterozoic oil deposits are attributed to the activity of cyanobacteria. They are also important providers of nitrogen fertilizer in the cultivation of rice and beans. The cyanobacteria have also been tremendously important in shaping the course of evolution and ecological change throughout earth’s history. The oxygen atmosphere that we depend on was generated by numerous cyanobacteria during the Archaean and Proterozoic Eras. Before that time, the atmosphere had a very different chemistry, unsuitable for life as we know it today.

Because they are photosynthetic and aquatic, cyanobacteria are often called “blue-green algae”. This name is convenient for talking about organisms in the water that make their own food, but does not reflect any relationship between the cyanobacteria and other organisms called algae. Cyanobacteria are relatives of the bacteria, not eukaryotes, and it is only the chloroplast in eukaryotic algae to which the cyanobacteria are related.

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Algae Form And Structure

The typical algae consists of a eukaryotic cell, resembling that of a plant, with a membrane bound nucleus, chloroplasts, and mitochondria. The chloroplasts photosynthesize sugars, which are broken down by the mitochondria. While many algae species are found as free-living unicellular organism, others take the form of colonies or multicellular organism. Below is a Euglena, a free-living unicellular algae. This algae has a thick pellicle, which spirals around the cell for protection. Other algae may have cell walls, or other protective coverings.

Other algae live in more complex arrangements. The colony of algae below rely on each other, but still function as individuals for the most part. As you can see, the algae on the outer edge of the colony are specialized for defense, carrying large spines. This helps the whole colony survive, without each algae having to produce spikes.

The largest algae, however, exist as multicellular organisms. These algae, like the kelp seen below, can grow hundreds of feet tall, exploiting the entire column of light in the ocean. Unlike most terrestrial plants, these plants are nonvascular, and do not have a special way to transport water. Thus, they must stay in the marine environment. They do have a number of adaptations which help them deal with the harsh conditions of the ocean, such as floating organs which carry them toward the light and specialized anchors which help root them to the ocean floor.

Where Algae Are Found

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Everywhere. Algae are found virtually all over the planet. The marine environment is saturated with them. The freshwater environment is also teeming with algae, as seen in any green pond or lake in the summertime. You might be surprised, but there are even algae which have colonized the terrestrial environment. Certain species of algae are found exclusively on snow-capped mountains, thousands of feet above sea level. Here, there is just enough sunlight, water, and nutrients for the algae to thrive.

While the majority of algae are found within the portion of the water column containing sunlight, scientists have also found organisms genetically similar to algae which do not photosynthesize. Thus, while photosynthesis was likely the shared feature of evolving algae, advanced derived forms have sometimes lost the need for it. These organisms can thrive where there is no sunlight, furthering the range of algae as a group.

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Algae Economically Valuable Organisms

The cell wall of algae gives us three very important products that are used widely on a commercial scale. These three products are agar, carrageenan, and alginate. All three products are used to thicken solutions or make gels. Agar is widely used in laboratories to grow micro-organisms. Carrageenan is used as a thickening compound in shaving creams and lotions, while alginate is commonly used by dentists to make impressions of your teeth when you need a new crown or braces.

Algae And Their Characteristics

As considered here, all of the algae are eukaryotic organisms, meaning their cells have nuclear material of deoxyribonucleic acid organized within a discrete, membrane-bounded organelle, known as the nucleus. In view of this definition, the so-called blue- are not discussed in this article, because those organisms are prokaryotic and are more appropriately referred to as blue-green bacteria , or as cyanobacteria. The cyanobacteria are also different from the true algae in that they do not contain the photosynthetic pigment known as chlorophylla, they do not have cell walls made of cellulose , and they do not store energy as starch or related polysaccharides.

Virtually all species of algae are photosynthetic. They have a relatively simple anatomy , which can range in complexity from single-celled organisms to colonial filaments, plates, or spheres, to the large, multicellular structures of the brown algae, known as thalli. Algal cell walls are generally made of cellulose, but can contain pectin, a class of hemicellulose polysaccharides that give the algae a slimy feel. The larger, multicellular algae have relatively complex tissues, which can be organized into organ-like structures that serve particular functions.

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Economic Significance Of Algae

The most important economic products obtained from algae are associated with brown and red seaweeds, which can be utilized as food for people, and as resources for the manufacturing of industrial products. These seaweeds are mostly harvested from the wild, although increasing attention is being paid to the cultivation of large algae.

Some species of algae can be directly eaten by humans, and in eastern they can be especially popular, with various species used as foods. An especially common food is the red alga known as nori in and as laver in western , which has long been eaten by coastal peoples of and Japan. This alga is often used as a wrapper for other foods, such as rice or plums, or it may be cooked into a clear soup. Nori has been cultivated for centuries in eastern Asia. Another alga known as dulse or sea kale is consumed dried or cooked into various stews or soups. Other commonly eaten seaweeds include the sea lettuce , and murlins or edible kelp .

Potentially, seaweeds are quite nutritious foods, because about 50% of their weight occurs as carbohydrates, with smaller concentrations of proteins and fats, and diverse micronutrients, including iodine. In practice, however, seaweeds are not very nutritious foods for humans, because we do not have the enzymes necessary to metabolize the most abundant of the complex, algal carbohydrates.

How Does It Harm Fish

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Golden alga toxins attack cells, allowing excess water and waterborne chemicals inside. Some organisms have protective layers to prevent this, but the exposed cells on fish gills and fins are not so protected. Toxins attack the outside layer of cells, then the next layer is affected, and so on. Soon the gills are so badly damaged that they are unable to function. Blood vessels in the gills leak into the water. At the same time, toxins and other waterborne chemicals are getting into the circulatory system of the fish, damaging internal organs. Fish behave as if there is not enough oxygen in the water. They travel at the top of the water surface or rest on the bottom in edges and shallow areas.

Usually when a toxic bloom lasts one month or less, a partial fish kill occurs, and the water body recovers. Fish will get away from the bloom area if they can, seeking underwater springs and seeps or places where creeks flow in and dilute the toxins.

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