| Rhodochorton | |
|---|---|
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| Rhodochorton purpureum | |
Scientific classification  | |
| (unranked): | Archaeplastida |
| Division: | Rhodophyta |
| Class: | Florideophyceae |
| Order: | Acrochaetiales |
| Family: | Acrochaetiaceae |
| Genus: | Rhodochorton Nägeli [1] |
| Species | |
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Rhodochorton is a genus of filamentous red alga adapted to low light levels. It may form tufts or a thin purple "turf" up to 5 millimetres high. The filaments branch infrequently, usually at the tips. [2]
In most species of Rhodochorton, the spore does not persist in the mature plant; instead, a basal web of filaments acts as a holdfast. Indeed, all Rhodochorton species have distinct basal threads, usually forming a disc, and upright threads, which are typically thinner. [2] Lateral branches usually occur at or near the top of the patent cell, and branching is concentrated towards the tips of threads. [2]
The organism may encrust bare rock surfaces, or be epiphytic upon frondose algae - particularly Laminaria hyperborea . [3] It typically grows in the shadow of these larger algae, in the intertidal zone, [4] and its adaption to low light levels means it is also common in caves. [2] It reproduces in winter using tetrasporangia and don't bear any monosporangia. [5] Rhodochorton is typically marine, but R. investiens dwells in fresh water. [6] Sexual reproduction has never been observed. [7]
It suffers grazing pressure from gastropods and amphipods, but amazingly fragments of the algae are able to pass through the grazers' digestive tracts alive - grazing may actually form a mode of dispersal for the organism. [4]
Rhodochorton investiens displays a relatively simple life cycle for a red alga. [8]
In the Carposporophyte: a spermatium merges with a trichogyne (a long hair on the female sexual organ), which then divides to form carposporangia - which produce carpospores.
Carpospores germinate into gametophytes, which produce sporophytes. Both of these are very similar; they produce monospores from monosporangia "just below a cross wall in a filament" [8] and their spores are "liberated through apex of sporangial cell." [8]
The spores of a sporophyte produce tetrasporophytes. Monospores produced by this phase germinate immediately, with no resting phase, to form an identical copy of parent. Tetrasporophytes may also produce a carpospore, which germinates to form another tetrasporophyte.[ verification needed ] [8]
The gametophyte may replicate using monospores, but produces sperm in spermatangia, and "eggs"(?) in carpogonium. [8]
The species in the genus Rhodothamniella closely resemble Rhodochorton
A gametophyte is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis that on germination produce a new generation of gametophytes.
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, fungi and protozoa.
Alternation of generations is the predominant type of life cycle in plants and algae. In plants both phases are multicellular: the haploid sexual phase – the gametophyte – alternates with a diploid asexual phase – the sporophyte.
Brown algae are a large group of multicellular algae comprising the class Phaeophyceae. They include many seaweeds located in colder waters of the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and polar regions. Many brown algae, such as members of the order Fucales, commonly grow along rocky seashores. Most brown algae live in marine environments, where they play an important role both as food and as a potential habitat. For instance, Macrocystis, a kelp of the order Laminariales, may reach 60 m (200 ft) in length and forms prominent underwater kelp forests that contain a high level of biodiversity. Another example is Sargassum, which creates unique floating mats of seaweed in the tropical waters of the Sargasso Sea that serve as the habitats for many species. Some members of the class, such as kelps, are used by humans as food.
In biology, a biological life cycle is a series of stages of the life of an organism, that begins as a zygote, often in an egg, and concludes as an adult that reproduces, producing an offspring in the form of a new zygote which then itself goes through the same series of stages, the process repeating in a cyclic fashion.
The green algae are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as a sister of the Zygnematophyceae. Since the realization that the Embryophytes emerged within the green algae, some authors are starting to include them. The completed clade that includes both green algae and embryophytes is monophyletic and is referred to as the clade Viridiplantae and as the kingdom Plantae. The green algae include unicellular and colonial flagellates, most with two flagella per cell, as well as various colonial, coccoid and filamentous forms, and macroscopic, multicellular seaweeds. There are about 22,000 species of green algae. Many species live most of their lives as single cells, while other species form coenobia (colonies), long filaments, or highly differentiated macroscopic seaweeds.
A sporophyte is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
Cladophora is a genus of reticulated filamentous Ulvophyceae.
A prothallus, or prothallium, is usually the gametophyte stage in the life of a fern or other pteridophyte. Occasionally the term is also used to describe the young gametophyte of a liverwort or peat moss as well. In lichens it refers to the region of the thallus that is free of algae.
Plant reproduction is the production of new offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from either parent. Asexual reproduction produces new individuals without the fusion of gametes, resulting in clonal plants that are genetically identical to the parent plant and each other, unless mutations occur.
Dictyotales is a large order in the brown algae containing the single family Dictyotaceae. Members of this order generally prefer warmer waters than other brown algae, and are prevalent in tropical and subtropical waters thanks to their many chemical defenses to ward off grazers. They display an isomorphic haplodiploid life cycle and are characterized by vegetative growth through a single apical cell. One genus in this order, Padina, is the only calcareous member of the brown algae.
Sporogenesis is the production of spores in biology. The term is also used to refer to the process of reproduction via spores. Reproductive spores were found to be formed in eukaryotic organisms, such as plants, algae and fungi, during their normal reproductive life cycle. Dormant spores are formed, for example by certain fungi and algae, primarily in response to unfavorable growing conditions. Most eukaryotic spores are haploid and form through cell division, though some types are diploid sor dikaryons and form through cell fusion.we can also say this type of reproduction as single pollination
Polysiphonia is a genus of filamentous red algae with about 19 species on the coasts of the British Isles and about 200 species worldwide, including Crete in Greece, Antarctica and Greenland. Its members are known by a number of common names. It is in the order Ceramiales and family Rhodomelaceae.
Myriotrichia is a genus of brown algae.
Asparagopsis armata is a species of marine red algae, in the family Bonnemaisoniaceae. English name(s) include red harpoon weed. They are multicellular eukaryotic organisms. This species was first described in 1855 by Harvey, an Irish botanist who found the algae on the Western Australian coast. A. armata usually develops on infralittoral rocky bottoms around the seawater surface to around 40m of depth. Marine algae like A. armata are considered "autogenic ecosystem engineers" as they are at the very bottom of the food chain and control resource availability to other organisms in the ecosystem.
Red algae, or Rhodophyta, are one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority of species (6,793) are found in the Florideophyceae (class), and mostly consist of multicellular, marine algae, including many notable seaweeds. Red algae are abundant in marine habitats but relatively rare in freshwaters. Approximately 5% of red algae species occur in freshwater environments, with greater concentrations found in warmer areas. Except for two coastal cave dwelling species in the asexual class Cyanidiophyceae, there are no terrestrial species, which may be due to an evolutionary bottleneck in which the last common ancestor lost about 25% of its core genes and much of its evolutionary plasticity.
Ectocarpus siliculosus is a filamentous brown alga. Its genome was the first brown macroalgal genome to be sequenced, with the expectation that E. siliculosus will serve as a genetic and genomic model for brown macroalgae.
Bangia is an extant genus of division Rhodophyta that grows in marine or freshwater habitats. Bangia has small thalli with rapid growth and high reproductive output, and exhibits behavior characteristic of r-selected species. The plants are attached by down-growing rhizoids, usually in dense purple-black to rust-colored clumps. The chloroplasts of Bangia, like others in the division Rhodophyta, contain chlorophyll a and sometimes chlorophyll d, as well as accessory pigments such as phycobilin pigments and xanthophylls. Depending on the relative proportions of these pigments and the light conditions, the overall color of the plant can range from green to red to purple to grey; however, the red pigment, phycoerythrin, is usually dominant.
Scytothamnus australis is a brown alga species in the genus Scytothamnus found in New Zealand. It is a sulphated polysaccharide and the type species in the genus.
Crustaphytum is a genus of red alga first discovered in Taoyuan algal reefs by Taiwanese scientists. The epithet “crusta” refers to crustose thallus and “phytum” refers to plant. Belonging to the family Hapalidiaceae in the order Hapalidiales, Crustaphytum is one kind of crustose coralline algae.
| Authority control databases: National |
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