Algae

Algae ( , ; : alga ) are any of a large and diverse group of photosynthetic organisms. It excludes the land plants (embryophytes). Such organisms range from microscopic unicellular microalgae (including cyanobacteria and phytoplankton) to seaweeds, multicellular macroalgae which may grow up to in length. Most algae are aquatic (especially marine), and some form cohesive colonies. Freshwater algae include Charophyta such as the filamentous Spirogyra and the grasslike stoneworts. Most algae are planktons carried passively by water, although some macroalgae have holdfasts for anchorage.

A diatom (Neo-Latin diatoma) is any member of a large group comprising several genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's biomass. They generate about 20 to 50 percent of the oxygen produced on the planet each year, take in over 6.7 billion tonnes of silicon each year from the waters in which they live, and constitute nearly half of the organic material found in the oceans. The shells of dead diatoms are a significant component of marine sediment, and the entire Amazon basin is fertili

rapid increase or accumulation in the population of algae

Chromalveolata was a eukaryote supergroup present in a major classification of 2005, then regarded as one of the six major groups within the eukaryotes. It was a refinement of the kingdom Chromista, first proposed by Thomas Cavalier-Smith in 1981. Chromalveolata was proposed to represent the organisms descended from a single secondary endosymbiosis involving a red alga and a bikont. The plastids in these organisms are those that contain chlorophyll c.

thumb |upright=1.2 |A digestive tubule cell of the sea slug Elysia clarki, packed with chloroplasts taken from green algae. C = [[chloroplast, N = cell nucleus. Electron micrograph: scale bar is 3 μm.]]

AlgaeBase is a global species database of information on all groups of algae, both marine and freshwater, as well as sea-grass.

thumb|270px|Cross section of a Chlamydomonas reinhardtii algae cell, a 3D representation

thumb|300px|Lake Erie in October 2011, during an intense cyanobacteria bloom

algal communities in sea ice or terrestrial ice

thumb|Diagram of a four membraned plastid containing a nucleomorph Nucleomorphs are small, vestigial eukaryotic nuclei found between the inner and outer pairs of membranes in certain plastids. They are thought to be vestiges of red and green algal nuclei that were engulfed by a larger eukaryote. Because the nucleomorph lies between two sets of membranes, nucleomorphs support the endosymbiotic theory and are evidence that the plastids containing them are complex plastids. Having two sets of membranes indicate that the plastid, a prokaryote, was engulfed by a eukaryote, an alga, which was then e

thumbnail|Intercalary located akinete of Dolichospermum smithii thumbnail|Terminally located akinete of Gloeotrichia thumb|right|Akinetes, also termed "cysts", of Haematococcus An akinete is an enveloped, thick-walled, non-motile, dormant cell formed by both cyanobacteria and algae. Cyanobacterial akinetes are mainly formed by filamentous, heterocyst-forming members under the order Nostocales and Stigonematales. Eukaryotic microalgae also produce akinetes, such as Haematococcus.

Phycobiliproteins are water-soluble proteins present in cyanobacteria and certain algae (rhodophytes, cryptomonads, glaucocystophytes). They capture light energy, which is then passed on to chlorophylls during photosynthesis. Phycobiliproteins are formed of a complex between proteins and covalently bound phycobilins that act as chromophores (the light-capturing part). They are most important constituents of the phycobilisomes. thumb|Phycobilisome structure

Euglenophyceae (ICNafp, proposed as a class) or Euglenea (ICZN, proposed as a class) is an unranked clade of single-celled algae belonging to the phylum Euglenozoa. They have chloroplasts originated from an event of secondary endosymbiosis with a green alga. They are distinguished from other algae by the presence of paramylon as a storage product and three membranes surrounding each chloroplast.

one of many types of microbial mat that forms on the surface of water or

biological water filter that uses light to grow algae which removes undesirable chemicals from aquarium water

Phycotechnology refers to the technological applications of algae, both microalgae and macroalgae.

Group of photosynthetic plankton

Microcystin-LR (MC-LR) is a toxin produced by cyanobacteria. It is the most toxic of the microcystins.

group of freshwater micro-algae