Caulerpa racemosa | |
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Scientific classification | |
Clade: | Viridiplantae |
Division: | Chlorophyta |
Class: | Ulvophyceae |
Order: | Bryopsidales |
Family: | Caulerpaceae |
Genus: | Caulerpa |
Species: | C. racemosa |
Binomial name | |
Caulerpa racemosa | |
Synonyms | |
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Caulerpa racemosa is a species of edible green alga, a seaweed in the family Caulerpaceae. It is commonly known as sea grapes (along with the related Caulerpa lentillifera ) and is found in many areas of shallow sea around the world. Despite the name, it is not related to grapes. There are a number of different forms and varieties, and one that appeared in the Mediterranean Sea in 1990, which is giving cause for concern as an invasive species.
There are about 75 species of Caulerpa. Many of them exhibit polymorphism, showing different growth forms in different habitats which makes them difficult to identify. C. racemosa, C. laetevirens and C. peltata form a species complex. A number of forms and varieties for C. racemosa are listed but further study is needed to clarify their exact phylogenetic relationships. [2] [1]
A plant of C. racemosa consists of a number of branches linked to stolons which are anchored to the sandy substrate by rhizoids. The branches are a few centimetres apart and can grow to a height of 30 centimetres (12 in). Many spherical or ovate side-shoots branch off these and give the seaweed its name of sea grapes. [3] Like other members of the order Bryopsidales, each C. racemosa plant consists of a single enormous cell with a large number of nuclei. The chloroplasts containing chlorophyll are free to migrate from any part of the organism to another and there is a network of fibrous proteins that helps movement of organelles. [4]
C. racemosa is widely distributed in shallow temperate and tropical seas. In 1926 a new form of the alga was reported off Tunisia, possibly an immigrant from the Red Sea, and this later spread to much of the eastern Mediterranean Sea. In 1990, a new, larger form with two vertical rows of branches on opposite sides of the stem was found off Libya. It spread widely, invading much of the Mediterranean Sea and becoming more widespread than the invasive species, Caulerpa taxifolia . It is known as var. cylindracea and may have originated from Australian waters. [5] In America C. racemosa is found in shallow water in the Caribbean Sea, around Bermuda and along the eastern seaboard of America from Florida to Brazil. [3]
In the Mediterranean, growth begins in April when new stolons develop and erect branches start growing, and continue till December, after which the plants decline and become dormant. [6]
C. racemosa reproduces vegetatively by fragmentation. When pieces of the plant get broken off they develop into new plants. Small pieces of tissue only a few millimetres across are capable of doing this. [7]
C. racemosa can also reproduce sexually and in so doing exhibits holocarpy. This means that all the organism's cytoplasm is used up in the creation of the gametes and only a husk remains at the site of the original plant. The plants are monoecious with male and female gametes being produced by the same plant and liberated into the water column where they unite to give spherical zygotes. These settle and after five weeks produce germ tubes which elongate and branch to develop into new plants. [8] Mass spawnings sometimes take place in the Caribbean Sea and normally do so just before dawn. There were 39 such mass spawnings during a period of 125 days and the days on which they took place showed no relation to the tidal or lunar cycles. [9] The gametes remain motile for about 60 minutes. Mass spawning is advantageous to the plant in increasing the chances of fertilisation. Underwater visibility can be reduced to less than one metre by the green cloud produced in the process. [10] Similar mass spawnings take place in the Mediterranean Sea causing a cloud of green gametes to be released in the water approximately 14 minutes before sunrise. [11]
Caulerpa species contain secondary metabolites that are cytotoxic, of which caulerpenyne is the most abundant. These deter animals from consuming the plants. A study has been done on herbivores that graze on meadows of the invasive C. cylindracea in the north west of its range in the Mediterranean. The sea breams Boops boops and Sarpa salpa were found to feed on the algae, as did the sea urchins Paracentrotus lividus and Sphaerechinus granularis . Other herbivores also grazed occasionally, but the total amount consumed was compensated for by the rapid growth of the plant and it was considered that these organisms were not likely to play a valuable role in bio-control of the plant. [6] C. taxifolia and C. racemosa show the great influence of substratum on their spatial distribution with a high colonization of the dead matte of the seagrass Posidonia oceanica [12]
C. racemosa and C. taxifolia are both invasive Lessepsian migrants. Caulerpenyne content is lesser in C. racemosa than in C. taxifolia. [13]
Like the closely related C. lentillifera , C. racemosa is edible. It is consumed widely in salads in Japan, Fiji, the Philippines, and Thailand. It is also eaten by local fishermen in Malaysia and Indonesia. They are rich in fiber, proteins, minerals (calcium and magnesium), folic acid, ascorbic acid, vitamin A, and vitamin B1 while also being low in fat. [14]
In addition to the nutritional qualities of C. racemosa, it also has anti bacterial and anti-oxidant properties but these characteristics are not yet fully explored. [15] These different biological activities provide a glimpse of biomedical innovations for the future. The properties are believed to come from a strain of rare endophytic actinomycetes that lives in symbiosis with C. racemosa and more particularly of the secondary metabolites produced (flavonoids and alkaloids [16] ). Extracts of C. racemosa are already tested to reduce different types of cancer [17] but also to fight against multi-drug resistant uropathogens (as K. Pneumoniae and P. aeruginosa ). The multi drug resistance is a major public health problem because by 2050 (World Health Organization WHO), 10 million people could die each year as a result of this evolution of bacteria against the current families of antibiotics. Moreover, a multitude of potential treatments for various pathologies have been identified, particularly for diabetes [18] and herpes. [19]
Chlorophyta is a division of green algae informally called chlorophytes.
The Ulvophyceae or ulvophytes are a class of green algae, distinguished mainly on the basis of ultrastructural morphology, life cycle and molecular phylogenetic data. The sea lettuce, Ulva, belongs here. Other well-known members include Caulerpa, Codium, Acetabularia, Cladophora, Trentepohlia and Monostroma.
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.
Caulerpa taxifolia is a species of green seaweed, an alga of the genus Caulerpa, native to tropical waters of the Pacific Ocean, Indian Ocean, and Caribbean Sea. The species name taxifolia arises from the resemblance of its leaf-like fronds to those of the yew (Taxus).
Caulerpa is a genus of seaweeds in the family Caulerpaceae. They are unusual because they consist of only one cell with many nuclei, making them among the biggest single cells in the world.
Halimeda is a genus of green macroalgae. The algal body (thallus) is composed of calcified green segments. Calcium carbonate is deposited in its tissues, making it inedible to most herbivores. However one species, Halimeda tuna, was described as pleasant to eat with oil, vinegar, and salt.
Codium is a genus of edible green macroalgae under the order Bryopsidales. The genus name is derived from a Greek word that pertains to the soft texture of its thallus. One of the foremost experts on Codium taxonomy was Paul Claude Silva at the University of California, Berkeley. Silva was able to describe 36 species for the genus, and in honor of his work on Codium, the species C. silvae was named after the late professor.
In botany, a zoid or zoïd is a reproductive cell that possesses one or more flagella, and is capable of independent movement. Zoid can refer to either an asexually reproductive spore or a sexually reproductive gamete. In sexually reproductive gametes, zoids can be either male or female depending on the species. For example, some brown alga (Phaeophyceae) reproduce by producing multi-flagellated male and female gametes that recombine to form the diploid sporangia. Zoids are primarily found in some protists, diatoms, green alga, brown alga, non-vascular plants, and a few vascular plants. The most common classification group that produces zoids is the heterokonts or stramenopiles. These include green alga, brown alga, oomycetes, and some protists. The term is generally not used to describe motile, flagellated sperm found in animals. Zoid is also commonly confused for zooid which is a single organism that is part of a colonial animal.
Bryopsidales is an order of green algae, in the class Ulvophyceae.
Udoteaceae is a family of green algae, in the order Bryopsidales.
Bryopsis, often referred to a hair algae, is a genus of marine green algae in the family Bryopsidaceae. Species in the genus are macroscopic, siphonous marine green algae that are made up of units of single tubular filaments. They can form dense tufts up to 40 cm in height. Each cell is made of up an erect thallus that is often branched into pinnules. Approximately 60 species have been identified in this genus since its initial discovery in 1809. The ecological success of Bryopsis has also been attributed to its associations with endophytic bacteria that reside in the cytoplasm of their cells.
Udotea is a genus of green algae in the family Udoteaceae.
Caulerpa lentillifera or sea grape is a species of ulvophyte green algae from coastal regions in the Asia-Pacific. This seaweed is one of the favored species of edible Caulerpa due to its soft and succulent texture. It is traditionally eaten in the cuisines of Southeast Asia, Oceania, and East Asia. It was first commercially cultivated in the Philippines in the 1950s, followed by Japan in 1968. Both countries remain the top consumers of C. lentillifera. Its cultivation has since spread to other countries, including Vietnam, Taiwan, and China. C. lentillifera, along with C. racemosa, are also known as sea grapes or green caviar in English.
Edible seaweed, or sea vegetables, are seaweeds that can be eaten and used for culinary purposes. They typically contain high amounts of fiber. They may belong to one of several groups of multicellular algae: the red algae, green algae, and brown algae. Seaweeds are also harvested or cultivated for the extraction of polysaccharides such as alginate, agar and carrageenan, gelatinous substances collectively known as hydrocolloids or phycocolloids. Hydrocolloids have attained commercial significance, especially in food production as food additives. The food industry exploits the gelling, water-retention, emulsifying and other physical properties of these hydrocolloids.
Halimeda tuna is a species of calcareous green seaweed in the order Bryopsidales. It is found on reefs in the Atlantic Ocean, the Indo-Pacific region and the Mediterranean Sea. Halimeda tuna is the type species of the genus Halimeda and the type locality is the Mediterranean Sea. The specific name "tuna" comes from the Taíno language, meaning "cactus" and referring to the resemblance of the thallus to the growth form of an Opuntia cactus.
Cymodocea nodosa is a species of seagrass in the family Cymodoceaceae and is sometimes known as little Neptune grass. As a seagrass, it is restricted to growing underwater and is found in shallow parts of the Mediterranean Sea and certain adjoining areas of the Atlantic Ocean.
Caulerpa prolifera is a species of green alga, a seaweed in the family Caulerpaceae. It is the type species of the genus Caulerpa, the type location being Alexandria, Egypt. It grows rapidly and forms a dense mass of vegetation on shallow sandy areas of the sea.
Ulva linza is a green alga in the family Ulvaceae that can be found in British Isles.
Caulerpa cylindracea is a species of seaweed in the Caulerpaceae family.