Crustaphytum | |
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Scientific classification | |
(unranked): | Archaeplastida |
Division: | Rhodophyta |
Class: | Florideophyceae |
Order: | Corallinales |
Family: | Hapalidiaceae |
Subfamily: | Melobesioideae |
Genus: | Crustaphytum L.-C.Liu &S.-M.Lin, 2018 |
Species [1] | |
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Crustaphytum is a genus of red alga first discovered in Taoyuan algal reefs by Taiwanese scientists. [2] 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 (also known as non-geniculate coralline algae). [3]
Crustaphytum goes through the triphasic life cycle, [4] a character of the phylum Rhodophyta, and all of its reproductive structures are protected by specialized conceptacles, sac-like structures that are situated in the receptacle. The triphasic life cycle alternates between haploid gametophytes, diploid carposporophytes, and diploid tetrasporophytes. Starting from gametophytes, both male and female gametes grow in conceptacles on the surface of the algal body (thalli). Male gametes then mature and are released through the cystic pore, entering the carpogonia and fertilize with female gametes. Afterwards, carposporophytes grow on the female gametophytes. Carpospores are produced and released when mature, developing into tetrasporophytes. Subsequently, four tetraspores are released from each conceptacle on the surface of the tetrasporophytes. As long as the tetraspores encounter suitable conditions, they will germinate and grow into gametophytes, completing a triphasic life cycle. [5]
The algal body is monomerous and non-geniculate, [6] consisting of thin and shell-like calcified leaflets (about 4 to 10 cm long and 3 to 5 cm wide), which can be irregularly fragmented or oval shaped. The dorsal surfaces of the calcified thalli are dark purple or dark red due to 5-10 layers or more of cortical cells containing photosynthetic pigments, and the ventral surfaces (towards the ground) grow closely to the reef matrix or other calcified organisms. Therefore, when observing Crustaphytum algae in the field, one can see that the edges of the calcified leaflets are wavy rather than tightly attached to the hard matrix. The thickness of the algal body is about 100 to 300 μm, with 35 to 45 cell layers. [4]
The appearance and size of the gametophyte and the tetrasporophyte look almost the same with naked eyes. To differentiate, on the one hand, one can observe the longitudinal section through mature thallus of the gametophyte. The area of medullary cells comprises approximately 70% of the thickness can be seen to grow radially from the coaxial core. Perithallial filaments in the dorsal region are composed of 7–10 celled layers, including one or two layers of epithelial cells and one layer of subepithallial cells. [3] Calcified crystal filaments in the meristem region are also radially arranged, and cell fusion is commonly found between adjacent cells. On the other hand, the tetrasporophyte has porous cavities with flat-topped tetrasporangia protruding from the surface of the algal body, and the each cavity has multiple bands divided similar to the Chinese character "目". To sum up, Crustaphytum can be separated from other related genera mainly by possessing coaxial thallus and relatively small tetrasporangiate conceptacle chambers (130 to 155 μm high by 115 to 200 μm wide). [2]
Crustaphytum prefers environments with higher nutrient salinity, higher sedimentation, and higher wave strength compared to corals. It mostly inhabits in lower intertidal zones attached to old algal reefs or pebbles, and sometimes it can be discovered in subtidal zones attached to rocks at 2–3 m depth. As of 2020, Crustaphytum pacificum has been recorded in northern Taiwan (mainly in Shimen and Taoyuan) and New Caledonia in southwestern Pacific Ocean. [2] Crustaphytum atlanticum was discovered in southeastern Brazil. [7]
Crustaphytum plays many ecologically significant roles. When alive, it not only is an important producer of coastal regions but also uses the carbon dioxide released during calcification to produce glucose. [8] Aside from that, the living algae can prevent the hard matrix from wave erosion, achieving the function of coastal protection. After death, it can form algal reefs, which creates habitat and provide shelter for many marine creatures. [9]
Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of red, but some species can be purple, yellow, blue, white, or gray-green. Coralline algae play an important role in the ecology of coral reefs. Sea urchins, parrot fish, and limpets and chitons feed on coralline algae. In the temperate Mediterranean Sea, coralline algae are the main builders of a typical algal reef, the Coralligène ("coralligenous"). Many are typically encrusting and rock-like, found in marine waters all over the world. Only one species lives in freshwater. Unattached specimens may form relatively smooth compact balls to warty or fruticose thalli.
Schmitzia hiscockiana is a small, rare, red seaweed or marine alga of the phylum Rhodophyta or red algae. It was discovered and named in 1985.
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.
Conceptacles are specialized cavities of marine and freshwater algae that contain the reproductive organs. They are situated in the receptacle and open by a small ostiole. Conceptacles are present in Corallinaceae, and Hildenbrandiales, as well as the brown Fucales. In the Fucales there is no haploid phase in the reproductive cycle and therefore no alternation of generations. The thallus is a sporophyte. The diploid plants produce male (antheridia) and female (oogonia) gametangia by meiosis. The gametes are released into the surrounding water; after fusion, the zygote settles and begins growth.
Phymatolithon is a genus of non geniculate coralline red algae, known from the UK, and Australia. It is encrusting, flat, and unbranched; it has tetrasporangia and bisporangia borne in multiporate conceptacles. Some of its cells bear small holes in the middle; this distinctive thallus texture is termed a "Leptophytum-type" thallus surface, and has been posited as a taxonomically informative character. It periodically sloughs off its epithallus, reducing its overgrowth by algae by as much as 50% compared to bare rock.
Peyssonnelia is a genus of thalloid red alga, named after naturalist Jean-André Peyssonnel (1694–1759) It includes the algae commonly known as rumoi-iwanokawa, mayoi-iwanokawa and akase-iwanokawa. Specimens can reach around 20 cm in size. Peyssonnelia produces tetraspores.
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.
Calliarthron is a genus containing two species of thalloid intertidal alga. Specimens can reach around 30 cm in size. The thalli take a crustose form. The organisms lack secondary pit connections. Calliarthron reproduces by means of conceptacles; it produces tetraspores, dispores and carpospores. The genus has lignin and contains secondary cell walls, traits which are normally associated with the vascular plants. It is similar to the genus Bossiella.
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.
Hildenbrandia is a genus of thalloid red alga comprising about 26 species. The slow-growing, non-mineralized thalli take a crustose form. Hildenbrandia reproduces by means of conceptacles and produces tetraspores.
The epithallium or epithallus is the outer layer of a crustose coralline alga, which in some species is periodically shed to prevent organisms from attaching to and overgrowing the alga.
Synarthrophyton is a genus of thalloid red algae comprising eight species. The monomerous, crustose thalli are composed of a single system of filaments which grow close to the underlying surface. Synarthrophyton reproduces by means of flask-shaped multiporate conceptacles; it produces tetraspores and dispores. Mucus plugs the opening of young conceptacles, which open as they mature.
Amphiroa is a genus of thalloid red algae under the family Corallinaceae.
Jania is a genus of red macroalgae with hard, calcareous, branching skeletons in the family Corallinaceae.
Spongites yendoi is a species of crustose red seaweed with a hard, calcareous skeleton in the family Corallinaceae. It is found on the lower shore as part of a diverse community in the southeastern Atlantic Ocean and the Indo-Pacific Ocean.
Hypnea is a genus of red algae, and a well known carrageenophyte.
Mastophora is a genus of thalloid alga comprising four species. The dimerous, crustose thalli comprise two groups of filaments. The bulk of the thallus is made of erect filaments, which may be one or many cells long. These grow approximately perpendicular to the filaments of a basal layer, usually one cell thick. haustoria, haustoria, and palisade cellsare present in the organisms but lack secondary pit connections. Mastophora reproduces by means of conceptacles; it produces tetraspores and dispores.
Halosaccion glandiforme, also known as sea sacs or sea grapes, is a species of red algae.
Hildenbrandia rubra is a marine species of thalloid red alga. It forms thin reddish crusts on rocks and pebbles in the intertidal zone and the shallow subtidal zone. It is a common species with a cosmopolitan distribution, and is able to tolerate a wide range of conditions.
Amphiroa beauvoisii is a species of thalloid red algae in the Corallinaceae family. It is widely distributed across the world, and can be found attached to rocks in intertidal areas. Individual organisms consist of a base of calcified material, tissue in the shape of branching fan-like planes growing out of it. It exhibits a wide range of morphologies based on where it is found, as well as different reproductive behaviors based on season and location.