Early life on Earth limited by enzyme

The enzyme-nitrogenase-can be traced back to the universal common ancestor of all cells more than four billion years ago.

The surprising merit of giant clam feces

Coral reefs are a hotspot of biodiversity, hosting numerous species of animals and fish that help one another maintain a harmonious environment. One of these species is the giant clam. They are the biggest shellfish in the ...

Slow start for blue-green algae on Alberta lakes

There have been fewer health advisories than usual about blue-green algae in Alberta lakes this past summer but that doesn't mean the problem is going away, explained a University of Alberta biologist.

Algae-killing viruses spur nutrient recycling in oceans

Scientists have confirmed that viruses can kill marine algae called diatoms and that diatom die-offs near the ocean surface may provide nutrients and organic matter for recycling by other algae, according to a Rutgers-led ...

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Algae (pronounced /ˈældʒiː/; singular alga /ˈælɡə/, Latin for "seaweed") are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in land plants. For that reason they are currently excluded from being considered plants.

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to as Blue-green Algae) were traditionally included as "Algae" in older textbooks, many modern sources regard this as outdated and restrict the term Algae to eukaryotic organisms. All true algae therefore have a nucleus enclosed within a membrane and chloroplasts 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 chloroplasts seem to have a single origin.

Algae lack the various structures that characterize land plants, such as phyllids and rhizoids in nonvascular plants, or leaves, roots, and other organs that are found in tracheophytes. Many are photoautotrophic, 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 the 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 dating back to 1.6 to 1.7 billion years ago.

The first alga to have its genome sequenced was Cyanidioschyzon merolae.

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