What is Algae: Definition and 24 Discussions

Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as Chlorella, Prototheca and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to 50 metres (160 ft) in length. Most are aquatic and autotrophic and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem, which are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the Charophyta, a division of green algae which includes, for example, Spirogyra and stoneworts.
No definition of algae is generally accepted. One definition is that algae "have chlorophyll as their primary photosynthetic pigment and lack a sterile covering of cells around their reproductive cells". Likewise, the colorless Prototheca under Chlorophyta are all devoid of any chlorophyll. Although cyanobacteria are often referred to as "blue-green algae", most authorities exclude all prokaryotes from the definition of algae. Algae constitute a polyphyletic group since they do not include a common ancestor, and although their plastids seem to have a single origin, from cyanobacteria, they were acquired in different ways. Green algae are examples of algae that have primary chloroplasts derived from endosymbiotic cyanobacteria. Diatoms and brown algae are examples of algae with secondary chloroplasts derived from an endosymbiotic red alga. Algae exhibit a wide range of reproductive strategies, from simple asexual cell division to complex forms of sexual reproduction.Algae lack the various structures that characterize land plants, such as the phyllids (leaf-like structures) of bryophytes, rhizoids in nonvascular plants, and the roots, leaves, and other organs found in tracheophytes (vascular plants). Most are phototrophic, although some are mixotrophic, deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy, myzotrophy, or phagotrophy. Some unicellular species of green algae, many golden algae, euglenids, dinoflagellates, and other algae have become heterotrophs (also called colorless or apochlorotic algae), sometimes parasitic, relying entirely on external energy sources and have limited or no photosynthetic apparatus. Some other heterotrophic organisms, such as the apicomplexans, are also derived from cells whose ancestors possessed plastids, but are not traditionally considered as algae. Algae have photosynthetic machinery ultimately derived from cyanobacteria that produce oxygen as a by-product of photosynthesis, unlike other photosynthetic bacteria such as purple and green sulfur bacteria. Fossilized filamentous algae from the Vindhya basin have been dated back to 1.6 to 1.7 billion years ago.Because of the wide range of types of algae, they have increasing different industrial and traditional applications in human society. Traditional seaweed farming practices have existed for thousands of years and have strong traditions in East Asia food cultures. More modern algaculture applications extend the food traditions for other applications include cattle feed, using algae for bioremediation or pollution control, transforming sunlight into algae fuels or other chemicals used in industrial processes, and in medical and scientific applications. A 2020 review, found that these applications of algae could play an important role in carbon sequestration in order to mitigate climate change while providing valuable value-add products for global economies.

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  1. B

    (Moved) Mass Algae Farm for Carbon Sequestration

    Summary:: Not looking for concrete answers, just want to spitball some ideas about the basics of Algae cultivation and implications of scaling to large scale. So the idea is this: Build massive ponds and seed them with an initial culture of algae. Wait one doubling period and filter out half...
  2. C

    Chemical/Paint Algae Carbon Capture: Make Your Own Algae Tank & Absorb CO2

    I'm just devastated by the news of climate change as of late, and I knew it was worrying but I've never been more worried about it in my life than I am right now. Have we truly passed the point of no return? Are we all doomed? Or do we still have time? Is algae carbon capture the way out? And...
  3. 256bits

    Crimson Snow Algae: Ancient Reports & Impact of Climate Change

    There was/is a recent report of red snow in Antartica, Ukranian Research station Verdnasky which got me interested. I had never heard of this phenomenom before. While some colored snow can be attributed to mineral content, this particular red snow is biological in origin. Apparantly reports go...
  4. S

    What kingdoms are blue-green, green & red algae?

    AIUI, there are these 3 types of algae, with blue-green algae being technically bacteria, green algae being plants, but what are red algae?
  5. BillTre

    Award Winning Pictures of Algae

    Six nice pix of kinds of algae you don't usually see http://www.brphycsoc.org/Canter_Lund_2018/index.lasso.
  6. Sundog

    Algae Nutrient Uptake: Diffusion or Active Transport?

    Does anyone know how algae take in nutrients? Is it by diffusion or active transport?
  7. M

    What Does a Phycologist Study?

    I am a Newbie to the biology forum. Have 43 years of experience in applied microbiology and biochemical engineering
  8. Priyadarshini

    What Are the Taxonomic Classifications of Algae?

    Does algae fall under the plant kingdom or thr protista kingdom? Why does blue-green algae fall under thr kingdom monera if it is a kind of algae? Thanks for any help in advance!
  9. physicist007

    Which green algae is indicator

    Could anyone tell me that what is the name of the unicellular green algae which acts as an indicators of clean water. Actually I am solving a crossword puzzle so I need assist in one question the hint to this specific algae is that it is an 7 letters long word and its second letter is E.
  10. P

    Bacteria only found in dry areas as cysts?

    Hi! I'm doing a worksheet on Body Size, Heat Loss and SA/Vol Ratio. The question I'm confused by is: "The smallest organisms such as bacteria, protozoa and unicellular algae live in water or a saturated atmosphere. They are only found in dry situations as cysts or spores. Why?" The wording...
  11. Pythagorean

    Solar powered vertebrate (through symbiosis with algae)

  12. C

    Algae producing oxygen in diving cylinder?

    Since algae can produce oxygen in closed containers, which you can inhale as a byproduct, when provided CO2 from your lungs; you could in theory take diving cylinders filled with algae with you, when diving, correct? I suppose this hasn't been done before, why not?
  13. K

    Toxic Algae Bloom in Lake Erie: What should be done?

    How do we fix this? The green scum shown in this image is the worst algae bloom Lake Erie has experienced in decades. Such blooms were common in the lake’s shallow western basin in the 1950s and 60s. Phosphorus from farms, sewage, and industry fertilized the waters so that huge algae...
  14. T

    How do i turn algae into fuel?

    Hi, I am doing this science fair thing and for it I've decided to power something using biofuel from algae. I have everything i need to grow algae but I am not sure how to get from algae to biofuel. Could someone please tell me or suggest a website about how this process works. It would also...
  15. J

    Solving a Word Problem: Algae Increase by Factor of 4 Every 60 Days

    Homework Statement I just translated this word problem: The zone of a alga increases every 2 month about the factor 4. How many days does the alga needs to increse into the double? How many days ago has the alga been the half? Homework Equations The Attempt at a Solution...
  16. Ivan Seeking

    Is Algae and Bacteria the Perfect Combination for Biodiesel Production?

    A number of strains of microalgae are known to produce relatively high yields of energy as fuel stock [pre-biodiesel] in the form of plant oils, as a function of area and time - typically as BTU/acre-year, or MJ/hectare-day, etc. From a review of the literature, it is my perception that...
  17. A

    How does algae form in my pool?

    Just wondering how does algae get into my pool? Is it transported through insects from other bodies of water or something else??
  18. DaveC426913

    Treating Green Algae in a Goldfish Pond: Visibility ~2 Inches

    How do I treat a goldfish pond green with algae? Visibility is ~2 inches. It's not the wall coating I'm concerned about, it's the water itself. I know how I'd treat it indoors - with a scraper and a water change, but that won't work in a pond. (Well, I suppose a water change would help...)...
  19. B

    Extracting Oils from Algae for Biodiesel: Exploring Efficient Processes

    I have read the ASP ( Aquatic Species Program) report about growing Algae and have it processed to be used as a feedstock for Biodiesel . Given that 60% of the body mass of algea is usable oil as compared to only 15% at best from any land grown plant source. My question is what process can...
  20. E

    Algae Control: Oxidizers and Flocculants

    anyone here know how does oxidizers kill off those algae?i know that oxygen atoms are produced but am not sure the mechanism that cause the death of the algae. also how do flocculants actually work in clumping the algae together?
  21. N

    Algae & pH: Relationship, Causes & Effects

    what is the relationship between Algae and pH value? why there are more algae ,pH value rises?
  22. E

    Algaecides control algae growth?

    anyone here know how algaecides control algae growth?specificity? any other methods on controlling algae growth would b greatly appreciated
  23. T

    Can Guppies, Algae Eaters, & Albano Corys Tolerate Salt in Water?

    Can guppys, a alage eater, and a albanio cory tolerate salt in their water?
  24. screwball

    Research Nitrogen Fixation in Blue Green Algae

    Does anyone know where I could find some research on the rate at which nitrogen fixation occurs in blue green algae? Im looking for some sort of formula to calculate the amount of fixed nitrogen produced by a certain amount of blue green algae. Hopeing someone has seen something somewhere on...