Algae (singular alga) are very simple plants which can vary from the microalgae (microscopic) to macroalgae (large seaweeds) like kelp, which can grow more than 100 feet long. When we talk of microalgae, we denote microscopic organisms that include cyanobacteria (akin to bacteria) as well as the green, red and brown varieties of algae.
In fact, algae are a vast group of different types of organisms that produce their own food through photosynthesis. While a number of algae forms are quite large and multi-cellular, they are entirely different from the plants. Unlike plants, the cells of algae are not distinctly organized into diverse types of tissues that a meant for diverse functions.
This group of living things comprises an extensive range of organisms that are not closely related to each other all the time. The resemblances in the form of different groups of algae are usually owing to their parallel evolution wherein diverse organisms have adjusted themselves in comparable ways to fill same kind of niches. Algae are portrayed as polyphyletic. In other words, all members of the group do not have the same ancestor.
Not all, but nearly all microalgae grow through the process known as photosynthesis – they use sunlight, CO2, phosphorus and nitrogen, in addition to some nutrients to produce their own food, which is called biomass. This type of growth is known as “autotrophic” growth. However, there are some algae that have the ability to grow in the dark. This type of algae makes use of sugar or starch for growth. This type of growth is known as “heterotrophic” growth. Some groups of algae grow by combining both the processes and this type of growth is known as “mixotrophic” growth.
Algae are of diverse types and they are present in nearly all places on the Earth. They have a vital role in several ecosystems – which includes providing the base for different aquatic food chains that support the fisheries both in the ocean as well as inland. In addition, algae produce almost 70 percent of the air that we breathe to remain alive.
In present times, all types of algae are defined as eukaryotes. This means that the DNA within the cells of algae is present inside a nucleus that is surrounded by a membrane. Organisms whose cells are devoid of a nucleus are known as prokaryotes. Apart from algae, fungi, plants and animals are also eukaryotes.
On the other hand, bacteria and archaea are prokaryotes. There are various types of algae and they can be classified under different sub-groups largely on the basis of the color of their pigment, which is utilized in photosynthesis.
Types of algae
Broadly speaking, there are four main types of algae – green algae, red algae, brown algae and cyanobacteria (also known as the blue-green algae). Each of these forms of algae is described briefly below.
This form of algae is considered to be the predecessors of the land plants and they utilize the green plant pigment called chlorophyll for photosynthesis. In other words, like the land plants, green algae can produce their own food. Therefore, it is not surprising that some experts include green algae in the plant kingdom. However, many others like to consider the green algae as a separate group of living organism. Green algae can be both – single celled and multicellular. Some of them may be found living in colonies or forming elongated filaments comprising several cells. Several single-celled algae can move independently making use of their flagellae – which are elongated structures similar to whip. Many micro-organisms use flagellae for their locomotion. Usually, you can find green algae in various types of habitats, which may include the sea, fresh water, soil, damp walls and even tree trunks. However, most of the green algae are aquatic micro-organisms.
Many believe that the land plants actually evolved from a green algae variety – probably around 500 million years back. This belief is strengthened by the fact that green algae comprise chlorophyll as well as other pigments that are similar to those present in the land plants. In fact, they have some more similarities, such as the chlorophyll enclosed in their structures is known as chloroplasts. In addition, similar to the land plants, many varieties of green algae store sugars as starch granules.
This type of algae is also called rhodophyta. It is believed that red algae were among the maiden eukaryotic organisms on the Earth and signs of their existence have been discovered in rocks dating back to nearly 2 billion years. This type of algae is mainly marine organisms and they include several varieties of seaweed, in addition to many single-celled species. They get their red hue from two pigments – phycocyanin and phycoerythrin, which are used by red algae for photosynthesis. Phycocyanin and phycoerythrin absorb blue light that reaches further underneath the surface of the ocean compared to the red light, which is absorbed by chlorophyll. As a result, red algae or rhodophyta is capable of photosynthesizing deeper down in comparison to the green algae. This type of algae consists of coralline algae that make calcium carbonate shells for themselves. They are also capable of forming reefs.
The scientific name of this diverse group of algae is chromista. The members of this extreme group of algae range from microscopic, single-celled algae called diatoms to large, multi-cellular organisms – “kelp” seaweed that can grow up to a length of about 160 feet (50 meters). Brown algae make use of types of chlorophyll that is different from the chlorophyll used by land plants for photosynthesis. Brown algae or chromista contain other pigments like fucoxanthin which is responsible for the brown hue of these algae. On the other hand, diatoms are a vital constituent of the phytoplankton, which generate a major share of oxygen on the planet via photosynthesis. They also form the basis of several marine food chains. Similarly, kelp seaweeds are of great importance to the ecology as they have the ability to form widespread seafloor “forests”.
In present times, this group of algae is considered as bacteria. However, these micro-organisms are still known by their previous name “blue-green algae”. They are different from other groups of algae because they are basically prokaryotes – similar to all other bacteria. Nevertheless, unlike the bacteria, they possess the ability to produce their own food through photosynthesis. In fact, cyanobacteria are considered to be an ancient group and they were perhaps the first micro-organism to produce their own food through photosynthesis. According to many experts, a type of single-cell organisms incapable of photosynthesis may have symbiotic relationship with cyanobacteria in the recent past. They also believe that these bacteria may have possibly turned into chloroplasts, which are found in algae as well as plants in present times.
Health benefits and uses
Algae offer several benefits to us and for centuries, they have been used as food as well as medicine. Algae are usually considered to be super food as they are loaded with antioxidants, vitamins, proteins and essential minerals. The brown algae or chromista have been used for combating as well as treating heart disease, arthritis, stress and elevated levels of cholesterol. Similarly, the blue-green algae (cyanobacteria) offer many health benefits and are capable of combating depression, anxiety and fatigue.
Brown algae offer a variety of health benefits, including facilitating weight loss. This group of algae, also referred to as chromista, encloses a pigment that occurs naturally and is known as fucoxanthin. This pigment, which is responsible for the brown color of the algae, possesses the ability to burn out fat. According to the findings of a study, it has been found that on average women who took fucoxanthin were able to lose 1.5 pounds in 16 weeks. These women reported that they also experienced lower blood pressure and triglycerides, in addition to a positive loss of liver fat.
Findings of several studies have revealed that many groups of algae may be useful in inhibiting the growth of carcinogenic cells. According to the finding of one study, algae can combat pre-cancerous mouth sores – a condition known as oral leukoplakia. This study recommended taking one gram of spirulina daily for a year as it was found to be helpful in lessening the condition. There are a number of health benefits of algae and they include its ability to put off development of cancer, especially for people who chew tobacco.
Algae also help to keep the heart healthy. A scientific review done in 2013 showed that cyanobacteria or blue-green algae protects us from developing cardiovascular disease and also prevents non-alcoholic fatty liver disease. The health benefits of algae are attributed to the presence of gamma linolenic acid (GLA), carotenoids, dietary fiber, plant sterols and phycocyanin in these micro-organisms.
Among the other health benefits offered by algae are their ability to lessen inflammation and provide relief from pain. Algae enclose chlorophyll and the essential omega-3 fatty acids – both anti-inflammatory compounds that possess the ability to provide respite from pain associated with inflammatory conditions. A study undertaken in 2016 discovered that the red algae possess natural analgesic, anti-inflammatory and gastro-protective properties.
Findings of a study undertaken in 2016 showed that the health benefits from algae included the organism’s ability to bring down the levels of cholesterol. Algae enclose phytosterols that can help to lower the levels of low density lipo-protein (LDL) or “bad” cholesterol in the blood stream. Phytosterols are also helpful in reducing the absorption of cholesterol in the intestines when it is taken in the form of a supplement.
Algae also possess the ability to detoxify heavy metals and eliminate them from the body. In particular, the chlorella type of algae works as a natural detoxifying agent and help to get rid of mercury, lead, arsenic and aluminum from the body. Presence of these heavy metals in our body in whatever amount may lead to chronic or acute toxicity. In turn, this may damage our vital organs as well as the central nervous system.
Algae also possess the capability to refurbish the damaged cells in our body. Findings of various studies have revealed that the blue-green algae (cyanobacteria) can especially be helpful in promoting proliferation of human stem cells. These micro-organisms inhibit the natural aging process by replacing the dying cells with new, healthy cells. At the same time, they also repair the damaged cells.
Aside from the health benefits, various forms of seaweed, particularly those belonging to the red algae group, are also consumed as food. These seaweeds also supply the body with many vital food additives and agar – a variety of gel that is used for the culture of micro-organisms.
Algae have another potential use and that is their use in biofuel production. These organisms grow very fast and, as far as nutritional requirements and conditions are concerned, they are absolutely undemanding. Therefore, they are able to provide an inexpensive as well as efficient means to accumulate biomass for fuel production.
Algae are loaded with various proteins and you can grow them to have much more protein content. This unique property of algae makes them a perfect animal feed. In addition, algae contain several other micronutrients which when added to animal feed can enrich its nutritional value.
When they think of producing vegetable oils, many people first think of peanuts, olives and safflowers. However, you can also obtain vegetable oils from algae. It is worth mentioning here that some people even predict that provided algae are grown and harvested in the right way, they possesses the ability to produce large quantities of vegetable oils compared to olives, peanuts and safflower.
Different from other plants, especially land plants, the amino acid profile of algae is complete. In other words, algae provide us with a complete protein. In addition, algae possess the ability to promote metabolic processes in humans in ways that the other plants may not be able to do. Algae also contain multiple nutrients, which include essential minerals as well as trace elements that are necessary for our best possible health.
Aside from their health benefits and use as food, algae are also used in the form of organic fertilizers as they are living organisms. When you use algae as fertilizer, it starts breaking down very quickly, thereby releasing plentiful nitrogen. Hence, they are considered to be an excellent source of nitrogen. Hence, you may use algae as an excellent organic fertilizer that helps the crops to grow very quickly.
It is interesting to note that you can also use algae to produce plastics in an environment friendly and bio-friendly way. If companies want to grow algae, they need to find enough sunlight and waste water. Basically, a number of companies have already started producing plastic products that are environment friendly using algae. Such plastic products include water bottles, and a new term – green plastic – has been coined to name such products.
As far as waste water treatment is concerned, algae can also be a very resourceful component. Currently, many companies are using micro algae culture in the form of a tertiary bio treatment measure for waste water treatment. In addition, algae are well equipped to produce biomass that can be utilized in multipurpose ways. Therefore, algae are a intriguing owing to their capability to make use of phosphorus and nitrogen in their growth process.