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, while 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.
Chondrus crispus—commonly called Irish moss or carrageenan moss —is a species of red algae which grows abundantly along the rocky parts of the Atlantic coasts of Europe and North America. In its fresh condition it is soft and cartilaginous, varying in color from a greenish-yellow, through red, to a dark purple or purplish-brown. The principal constituent is a mucilaginous body, made of the polysaccharide carrageenan, which constitutes 55% of its dry weight. The organism also consists of nearly 10% dry weight protein and about 15% dry weight mineral matter, and is rich in iodine and sulfur. When softened in water it has a sea-like odour. Because of the abundant cell wall polysaccharides, it will form a jelly when boiled, containing from 20 to 100 times its weight of water.
Fucus vesiculosus, known by the common names bladderwrack, black tang, rockweed, sea grapes, bladder fucus, sea oak, cut weed, dyers fucus, red fucus and rock wrack, is a seaweed found on the coasts of the North Sea, the western Baltic Sea and the Atlantic and Pacific Oceans. It was the original source of iodine, discovered in 1811, and was used extensively to treat goitre, a swelling of the thyroid gland related to iodine deficiency.
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.
The green algae are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that 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 (spherical), and filamentous forms, and macroscopic, multicellular seaweeds. There are about 22,000 species of green algae, many of which live most of their lives as single cells, while other species form coenobia (colonies), long filaments, or highly differentiated macroscopic seaweeds.
Palmaria palmata, also called dulse, dillisk or dilsk, red dulse, sea lettuce flakes, or creathnach, is a red alga (Rhodophyta) previously referred to as Rhodymenia palmata. It grows on the northern coasts of the Atlantic and Pacific Oceans. It is a well-known snack food. In Iceland, where it is known as söl, it has been an important source of dietary fiber throughout the centuries.
Ascophyllum nodosum is a large, common cold water seaweed or brown alga (Phaeophyceae) in the family Fucaceae. Its common names include knotted wrack, egg wrack, feamainn bhuí, rockweed, knotted kelp and Norwegian kelp. It grows only in the northern Atlantic Ocean, along the north-western coast of Europe including east Greenland and the north-eastern coast of North America. Its range further south of these latitudes is limited by warmer ocean waters. It dominates the intertidal zone. Ascophyllum nodosum has been used numerous times in scientific research and has even been found to benefit humans through consumption.
Alaria esculenta is an edible seaweed, also known as dabberlocks or badderlocks, or winged kelp, and occasionally as Atlantic Wakame. It is a traditional food along the coasts of the far north Atlantic Ocean. It may be eaten fresh or cooked in Greenland, Iceland, Scotland and Ireland. It is the only one of twelve species of Alaria to occur in both Ireland and in Great Britain.
Fucus serratus is a seaweed of the north Atlantic Ocean, known as toothed wrack, serrated wrack, or saw rack.
Pelvetia canaliculata, the channelled wrack, is a very common brown alga (Phaeophyceae) found on the rocks of the upper shores of Europe. It is the only species remaining in the monotypic genus Pelvetia. In 1999, the other members of this genus were reclassified as Silvetia due to differences of oogonium structure and of nucleic acid sequences of the rDNA.
Alaria is a genus of brown alga (Phaeophyceae) comprising approximately 17 species. Members of the genus are dried and eaten as a food in Western Europe, China, Korea, Japan, and South America. Distribution of the genus is a marker for climate change, as it relates to oceanic temperatures.
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.
Lobophora variegata is a species of small thalloid brown alga which grows intertidally or in shallow water in tropical and warm temperate seas. It has three basic forms, being sometimes ruffled, sometimes reclining and sometimes encrusting, and each form is typically found in a different habitat. This seaweed occurs worldwide. It is the type species of the genus Lobophora, the type locality being the Antilles in the West Indies.
Cystoseira foeniculacea is a species of brown alga in the genus Cystoseira.
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.
Anthony William Derek Larkum is a British plant scientist and academic based in Sydney. He is Professor Emeritus of Plant Sciences at the University of Sydney and Adjunct Professor at the University of Technology Sydney (UTS).
Phyllariopsis brevipes is a species of large brown algae, found in the subtidal zone in the Mediterranean Sea. It is the type species of the genus. Unlike other large brown macroalgae, it has a habitat requirement to grow on the living thalli of the crustose red alga Mesophyllum alternans.
Phyllariopsis purpurascens is a species of large brown algae, found in the subtidal zone of the Mediterranean Sea and the intertidal zone of Morocco, as observed by Lourenço et al. (2020). While it is functionally similar to kelp species, it is not in the order Laminariales.
Zanardinia is a monotypic genus of seaweed in the brown algae. The only species, Zanardinia typus, commonly known as penny weed, is native to the northeastern Atlantic Ocean and the Mediterranean Sea.
