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Unlike plants, fungi and most types of algae, most protozoa do not have a rigid external cell wall but are usually enveloped by elastic structures of membranes that permit movement of the cell. In some protozoa, such as the ciliates and euglenozoans , the outer membrane of the cell is supported by a cytoskeletal infrastructure, which may be ...
They are the photosynthetic protists, and can be found in most of the main clades, completely intermingled with heterotrophic protists which are traditionally called protozoa. [27] Algae exhibit the most diverse range of morphologies, from single flagellated or coccoid cells (e.g., cryptophytes, haptophytes, dinoflagellates, chromerids, many ...
Diatoms, unicellular algae that have siliceous cell walls. [46] They are the most abundant form of algae in the ocean, although they can be found in fresh water as well. [ 46 ] They account for about 40% of the world's primary marine production, and produce about 25% of the world's oxygen. [ 47 ]
Marine algae can be divided into six groups: green, red and brown algae, euglenophytes, dinoflagellates and diatoms. Dinoflagellates and diatoms are important components of marine algae and have their own sections below. Euglenophytes are a phylum of unicellular flagellates with only a few marine members. Not all algae are microscopic.
Some parasitic algae (e.g., the green algae Prototheca and Helicosporidium, parasites of metazoans, or Cephaleuros, parasites of plants) were originally classified as fungi, sporozoans, or protistans of incertae sedis, [44] while others (e.g., the green algae Phyllosiphon and Rhodochytrium, parasites of plants, or the red algae Pterocladiophila ...
It has a polymorphic life cycle, ranging from free-living cells to large colonies. [54] It has the ability to form floating colonies, where hundreds of cells are embedded in a gel matrix, which can increase massively in size during blooms. [55] As a result, Phaeocystis is an important contributor to the marine carbon [56] and sulfur cycles. [57 ...
They can be single-celled [1] or multicellular and include bacteria, archaea, viruses, and most protozoa, as well as some fungi, algae, and animals, such as rotifers and copepods. Many macroscopic animals and plants have microscopic juvenile stages .
Botanists treated them as a division of algae, named Pyrrophyta or Pyrrhophyta ("fire algae"; Greek pyrr(h)os, fire) after the bioluminescent forms, or Dinophyta. At various times, the cryptomonads, ebriids, and ellobiopsids have been included here, but only the last are now considered close relatives. Dinoflagellates have a known ability to ...