Search results
Results from the WOW.Com Content Network
A protist (/ ˈ p r oʊ t ɪ s t /) is any eukaryotic organism (one with cells containing a nucleus) that is not an animal, plant, or fungus.The protists do not form a natural group, or clade, since they exclude certain eukaryotes with whom they share a common ancestor; [a] but, like algae or invertebrates, the grouping is used for convenience.
[50] [51] Brown algae form a class containing about 2,000 recognised species, [52] mostly multicellular and including many seaweeds such as kelp. Unlike higher plants, algae lack roots, stems, or leaves. They can be classified by size as microalgae or macroalgae. Microalgae are the microscopic types of algae, not visible to the naked eye.
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. [28] Algae exhibit the most diverse range of morphologies, from single flagellated or coccoid cells (e.g., cryptophytes, haptophytes, dinoflagellates, chromerids, many ...
Some protozoa form close associations with symbiotic photosynthetic algae (zoochlorellae), which live and grow within the membranes of the larger cell and provide nutrients to the host. The algae are not digested, but reproduce and are distributed between division products.
[146] [147] Brown algae form a class containing about 2,000 recognised species, [148] mostly multicellular and including many seaweeds such as kelp. Unlike higher plants, algae lack roots, stems, or leaves. They can be classified by size as microalgae or macroalgae. Microalgae are the microscopic types of algae, not visible to the naked eye.
Its field of study therefore overlaps with the more traditional disciplines of phycology, mycology, and protozoology, just as protists embrace mostly unicellular organisms described as algae, some organisms regarded previously as primitive fungi, and protozoa ("animal" motile protists lacking chloroplasts).
Diagram of a ciliate. A cytostome (from cyto-, cell and stome-, mouth) or cell mouth is a part of a cell specialized for phagocytosis, usually in the form of a microtubule-supported funnel or groove. Food is directed into the cytostome, and sealed into vacuoles. Only certain groups of protozoa, such as the Ciliophora and Excavata, have ...
Flowering plants do not produce flagellate cells, but ferns, mosses, green algae, and some gymnosperms and closely related plants do so. [2] Likewise, most fungi do not produce cells with flagellae, but the primitive fungal chytrids do. [3] Many protists take the form of single-celled flagellates. Flagella are generally used for propulsion ...