Algae are any of a large and diverse group of photosynthetic, eukaryotic organisms. The name is an informal term for a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as Chlorella, Prototheca and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to 50 metres (160 ft) in length. Most are aquatic and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds. In contrast, the most complex freshwater forms are the Charophyta, a division of green algae which includes, for example, Spirogyra and stoneworts. Algae that are carried by water are plankton, specifically phytoplankton.
A lichen is a symbiosis of algae or cyanobacteria living among filaments of multiple fungi species, along with a yeast embedded in the cortex or "skin", in a mutualistic relationship. Lichens are important actors in nutrient cycling and act as producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); grow crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); have a powder-like appearance (leprose); or other growth forms.
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.
Crustose is a habit of some types of algae and lichens in which the organism grows tightly appressed to a substrate, forming a biological layer. Crustose adheres very closely to the substrates at all points. Crustose is found on rocks and tree bark. Some species of marine algae of the Rhodophyta, in particular members of the order Corallinales, family Corallinaceae, subfamily Melobesioideae with cell walls containing calcium carbonate grow to great depths in the intertidal zone, forming crusts on various substrates. The substrate can be rocks throughout the intertidal zone, or, as in the case of the Corallinales, reef-building corals, and other living organisms including plants, such as mangroves and animals such as shelled molluscs. The coralline red algae are major members of coral reef communities, cementing the corals together with their crusts. Among the brown algae, the order Ralfsiales comprises two families of crustose algae.
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.
In algal anatomy, a pit connection is a hole in the septum between two algal cells, and is found only in multicellular red algae − specifically in the subphylum Eurhodophytina, except haploid Bangiales. They are often stoppered with proteinaceous "pit plugs". By contrast, many fungi contain septal pores − an unrelated phenomenon.
Red algae, or Rhodophyta, make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest phyla of algae, containing over 7,000 recognized species within over 900 genera amidst ongoing taxonomic revisions. The majority of species (6,793) are Florideophyceae, and mostly consist of multicellular, marine algae, including many notable seaweeds. Red algae are abundant in marine habitats. Approximately 5% of red algae species occur in freshwater environments, with greater concentrations in warmer areas. Except for two coastal cave dwelling species in the asexual class Cyanidiophyceae, no terrestrial species exist, 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.
Coleochaetophyceae is a class of charophyte algae related to land plants. There are about 35 known species, and are predominantly found in freshwater where they live periphytic on the surface of aquatic plants, plastic bags and pebbles in the shallow littoral zone of freshwater lakes. These are small disc-shaped or filamentous species, and have true multicellular organisation with sexual and asexual reproduction. The discs never develop beyond a two-dimensional organization. Their mitogenome is the most intron rich organelle among the streptophyte algae.
Patella ferruginea, commonly known as the ferruginous limpet is a species of true limpet, a marine gastropod mollusk in the family Patellidae. It is a large limpet, endemic to the western Mediterranean Sea, and although common in the past, it is now rare and restricted to only a few locations.
Scutellastra aphanes is a species of sea snail, a true limpet, a marine gastropod mollusk in the family Patellidae, one of the families of true limpets. It is endemic to South Africa.
Scutellastra barbara is a species of sea snail, a true limpet, a marine gastropod mollusk in the family Patellidae, one of the families of true limpets.
Scutellastra kermadecensis is a species of true limpet, a marine gastropod mollusk in the family Patellidae. It is endemic to the Kermadec Islands.
Scutellastra longicosta, the long-spined limpet or the duck's foot limpet, is a species of true limpet, a marine gastropod mollusk in the family Patellidae, one of the families of true limpets. It is native to the coasts of South Africa where it is found on the foreshore. It cultivates a species of crustose brown algae in a "garden".
Trentepohlia aurea is a species of filamentous terrestrial green alga with a worldwide distribution. It grows on rocks, old walls and the trunks and branches of trees such as oaks, elms, and the Monterey cypress. The orange coloration results from carotenoid pigments in the algal cells. It is probably the most widespread and abundant species of Trentepohlia in the Britain and Ireland.
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 and the Indo-Pacific Oceans.
Ralfsia verrucosa is a species of crustose brown seaweed in the family Ralfsiaceae. It grows intertidally in temperate waters around the world. In South Africa it is part of a mutualistic relationship with a limpet.
Bonnemaisonia hamifera is a species of red alga in the family Bonnemaisoniaceae. Originally from the Pacific Ocean, it has been introduced into the northeastern Atlantic Ocean, where it is considered invasive on European coasts. It exists in two phases which, at one time, were thought to be different species; a medium-sized feathery form attached to other seaweeds, and a small tufted form known as Trailliella.
Phyllophora antarctica is a species of red alga in the family Phyllophoraceae. It is native to Antarctica where it grows in dim light on the underside of sea ice. Some of it becomes detached and accumulates in drifts on the seabed. Many different organisms live attached to the fronds or among them.
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.
Cymbula sanguinans, the giant pinkray limpet, is a species of giant limpet, a marine mollusc in the family Patellidae. It is native to the coast of South Africa. At one time thought to be a subspecies of Cymbula miniata, molecular analysis has shown C. sanguinans warrants being treated as a full species, despite there being no obvious morphological differences between the two. This makes difficult the task of deciding which of the previous research studies refer to C. sanguinans, and which refer to C. miniata.
