Algae (/ˈældʒiː/ or /ˈælɡiː/; singular alga /ˈælɡə/, Latin for "seaweed") are a very large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. Most are photosynthetic like plants, and "simple" because their tissues are not organized into the many distinct organs found in land plants. The largest and most complex marine forms are called seaweeds.
Though the prokaryotic cyanobacteria (commonly referred to as blue-green algae) were traditionally included as "algae" in older textbooks, many modern sources regard this as outdated as they are now considered to be bacteria. The term algae is now restricted to eukaryotic organisms. All true algae therefore have a nucleus enclosed within a membrane and plastids bound in one or more membranes. Algae constitute a paraphyletic and polyphyletic group, as they do not include all the descendants of the last universal ancestor nor do they all descend from a common algal ancestor, although their plastids seem to have a single origin. Diatoms are also examples of algae.
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 phyllids (leaves) and rhizoids in nonvascular plants, or leaves, roots, and other organs that are found in tracheophytes (vascular plants). Many are phototrophic, although some groups contain members that are mixotrophic, deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy, myzotrophy, or phagotrophy. Some unicellular species rely entirely on external energy sources and have limited or no photosynthetic apparatus.
Nearly all algae have photosynthetic machinery ultimately derived from cyanobacteria, and so 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.
Other articles related to "algae":
... Iran started investigating on producing algae from 2000 ... the richest area in the world for cultivating algae, because of high humidity, sunny weather, large unused area and with salty water ... The first version of algae based biofuel will be come available for industrial purpose at 2015 ...
... Bio Fuels Pty Ltd (A Victor Smorgon Group company) is developing algae biofuels technology in Victoria ... The oil from the algae will go into the BioMax biodiesel produced by Smorgon Fuels ... Algae.Tec is an advanced biofuels company focused on commercializing technology that produces algae to manufacture sustainable fuels such as bio diesel and green jet fuel ...
... Shewanella algae is a rod-shaped Gram-negative marine bacterium ... algae is also a facultative anaerobe with the ability to reduce iron, uranium and plutonium metabolically ... algae is of great interest to the United States Department of Energy because of its ability to reduce the amount of radioactive waste in groundwater by making it ...
... with certain single-celled green algae species that reside in the animals' gastrodermal cells ... These algae may be either zooxanthellae, zoochlorellae or both ... The sea anemone benefits from the products of the algae's photosynthesis, namely oxygen and food in the form of glycerol, glucose and alanine the algae in turn are assured a reliable exposure to sunlight ...
... Algae has been implemented in the production of biodegradable plastics by Cereplast, Inc ... An agreement has also been reached with the US Military to introduce more biodegradable plastics as it attempts to move away from petroleum based plastics and utilize more environmentally friendly alternatives ...
Famous quotes containing the word algae:
“there, where you live,
the algae of your dreams.”
—Denise Levertov (b. 1923)