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Algae lack the various structures that characterize plants (which evolved from freshwater green algae), such as the phyllids (leaf-like structures) and rhizoids of bryophytes (non-vascular plants), and the roots, leaves and other xylemic/phloemic organs found in tracheophytes (vascular plants). Most algae are autotrophic, although some are ...
Algae ranges from single floating cells to attached seaweeds, while vascular plants are represented in the ocean by groups such as the seagrasses and the mangroves. Larger producers, such as seagrasses and seaweeds , are mostly confined to the littoral zone and shallow waters, where they attach to the underlying substrate and are still within ...
In a reversal of the pattern on land, in the oceans, almost all photosynthesis is performed by algae and cyanobacteria, with a small fraction contributed by vascular plants and other groups. Algae encompass a diverse range of organisms, ranging from single floating cells to attached seaweeds. They include photoautotrophs from a variety of groups.
Algae is an informal term for a widespread and diverse group of photosynthetic protists which are not necessarily closely related and are thus polyphyletic. Marine algae can be divided into six groups: green , red and brown algae , euglenophytes , dinoflagellates and diatoms .
Primary production on land is a function of many factors, but principally local hydrology and temperature (the latter covaries to an extent with light, specifically photosynthetically active radiation (PAR), the source of energy for photosynthesis). While plants cover much of the Earth's surface, they are strongly curtailed wherever ...
Algae lack the various structures that characterize plants (which evolved from freshwater green algae), such as the phyllids (leaf-like structures) and rhizoids of bryophytes (non-vascular plants), and the roots, leaves and other xylemic/phloemic organs found in tracheophytes (vascular plants). Most algae are autotrophic, although some are ...
Some forams are kleptoplastic, retaining chloroplasts from ingested algae to conduct photosynthesis. [59] By trophic orientation, dinoflagellates are all over the place. Some dinoflagellates are known to be photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey (phagotrophy). [60]
Cyanobacteria are globally widespread photosynthetic prokaryotes and are major contributors to global biogeochemical cycles. [25] They are the only oxygenic photosynthetic prokaryotes, and prosper in diverse and extreme habitats. [26] They are among the oldest organisms on Earth with fossil records dating back at least 2.1 billion years. [27]