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.
Florideophyceae is a class of exclusively multicellular red algae. They were once thought to be the only algae to bear pit connections, but these have since been found in the filamentous stage of the Bangiaceae. They were also thought only to exhibit apical growth, but there are genera known to grow by intercalary growth. Most, but not all, genera have three phases to the life cycle.
Lemanea is a genus of freshwater red algae, in the order Batrachospermales. Both species are considered to be widespread in the northern hemisphere. Although placed in the Rhodophyta it in fact is green in colour.
Thorea is a genus of freshwater algae in the Phylum Rhodophyta. Thorea is a small alga with filaments up to 200 cm long, dark green in colour and not red as are marine Rhodophyta. The filaments have only as few secondary branches.
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.
In algal anatomy, a pit connection is a hole in the septum between two algal cells, and is found only in the red algae − specifically, all orders except the Porphyridiales and haploid Bangiales. They are often stoppered with proteinaceous "pit plugs". By contrast, many fungi contain septal pores − an unrelated phenomenon.
Hildenbrandiales is an order of crustose forms red alga which bear conceptacles and produce secondary pit-connections. They reproduce by vegetative gemmae as well as tetrasporangia, which are produced inside the conceptacles. The way in which the tetraspores are produced is unusual enough to justify the formation of this distinct order. Some members of the order are known from freshwater rivers as well.
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.
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.
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.
Compsopogonales is an order of mostly freshwater red algae.
Sirodotia Kylin (1912) is a genus of freshwater red alga which was described by Kylin in 1912, and placed in the Batrachospermaceae family.
Batrachospermaceae is a family of fresh water red algae (Rhodophyta). Genera within the Batrachospermaceae generally have a "Lemanea-type" life history with carpospores germinating to produce chantransia. Sporophyte phase with meiosis occurs in an apical cell to produce the gametophyte stage. Pit connections have two pit plug cap layers with the other layer enlarged. This family of freshwater red algae is uniaxial, meaning each filament with a single apical cell. The genera included within Batrachospermaceae are listed in the table below.
Cyanidiophytina is a subdivision of red algae.
Timothy (Tim) John Entwisle, is an Australian botanist, much of whose research work is in phycology (algae). See for example the articles. He was awarded a Ph.D. from La Trobe University in 1986 for work on the taxonomy of Vaucheria.
Naccariaceae is a family of red algae in the order Bonnemaisoniales, with 3 monotypic genera that are found in both the Pacific and Atlantic Oceans.
Liagoraceae is a family of red algae (Rhodophyta) in the order Nemaliales. The type genus is LiagoraJ.V.Lamouroux.
Halymeniales is an order of red algae belonging to the class Florideophyceae and the subclass Rhodymeniophycidae.
Peyssonneliales is a monotypic order of red algae belonging to the class Florideophyceae and the subclass Rhodymeniophycidae. It contains only 1 known family, PeyssonneliaceaeDenizot, M., 1968.
Kathleen "Kay" Margaret Cole was a Canadian phycologist, known as one of the world's leading experts in the cytology of marine algae. In 1998 the Canadian Botanical Society awarded her the George Lawson Medal for lifetime achievement.
