Caulerpa racemosa
Caulerpa racemosa
Sea grapes (Caulerpa racemosa J. Agardh, 1873) is a green algae belonging to the Caulerpaceae family.
Systematics –
Domain Eukaryota,
Kingdom Plantae,
Division Chlorophyta,
Class Bryopsidophyceae,
Order Bryopsidales,
Family Caulerpaceae,
Genus Caulerpa,
Species C. racemosa.
The term is a basionym:
– Fucus racemosus Forssk..
The terms are synonymous:
– Caulerpa clavifera (Turner) C.Agardh;
– Caulerpa feldmannii Rayss & Edelstein, 1960;
– Caulerpa obtusa J.V.Lamour., 1809;
– Caulerpa racemosa f. requienii (Mont.) Weber van Bosse, 1913;
– Caulerpa racemosa var. disticha V.J.Chapman, 1977;
– Caulerpa racemosa var. mucronata L.N.de Senerpont Domis, 2003;
– Caulerpa uvifera (Roth) C.Agardh, 1817;
– Chauvinia clavifera (Turner) Bory de Saint-Vincent, 1829
– Caulerpa clavifera (Turner) C.Agardh, 1817
– Fucus clavifer Turner, 1807;
– Fucus racemosus Forssk.;
– Fucus uvifer Turner, 1811.
Within this species, some varieties and forms can be recognized, including:
– Caulerpa racemosa var. chemnitzia;
– Caulerpa racemosa var. clavifera (C. Agardh) Weber-van Bosse, 1909
– Caulerpa racemosa var. corynephora (Mont.) W.V.Bosse;
– Caulerpa racemosa var. lamourouxii (Turner) Weber Bosse;
– Caulerpa racemosa var. racemosa;
– Caulerpa racemosa var. uvifera (C. Agardh) J. Agardh, 1873
– Caulerpa racemosa f. racemosa;
– Caulerpa racemosa f. simplicissima Børgesen, 1949.
Etymology –
The term Caulerpa comes from the ancient Greek kaulos (καυλός, “stem”) and herpo (ἕρπω, “to creep”), meaning “stem (that) creeps”.
The epithet racemosa comes from the Latin racemosus, meaning made in a cluster, due to the characteristic of the inflorescences.
Geographical Distribution and Habitat –
Caulerpa racemosa is a seaweed native to the Red Sea, but is an alien species of the Mediterranean Sea, where it entered through the Suez Canal since 1926, when a new form of the seaweed was reported off Tunisia, perhaps an immigrant from the Red Sea, and later spread throughout 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 in Australian waters. In America, C. racemosa is found in shallow waters in the Caribbean Sea, around Bermuda and along the eastern coast of America from Florida to Brazil.
In the Mediterranean, together with Caulerpa taxifolia, it is threatening the meadows of Posidonia oceanica, of which it is a strong competitor.
This alga is widely distributed in shallow temperate and tropical seas.
Description –
Caulerpa racemosa is a green alga that forms stolons, from which fronds branch out upwards, containing photosynthetic structures and rhizoids directed upwards, with which it adheres firmly to the substrate. It is a unicellular alga, in which the cell wall covers a single protoplast.
Cultivation –
Caulerpa racemosa is a monoecious alga capable of reproducing both through sexual and vegetative reproduction. Sexual reproduction occurs through anisogamy with alternating gametophytic and sporophytic generation, where the former typically prevails. Starting from the cytoplasm, four anisogametes are released simultaneously, causing the subsequent death of the individual. Vegetative multiplication can occur through:
– growth, one part of the plant dies, the other end continues to grow;
– fragmentation, which can be caused by human activities, wave motion and predators;
– formation of propagules.
While the reproductive process is now known, its activation signals remain unknown.
Uses and Traditions –
From a taxonomic point of view, about 75 species of Caulerpa are recognized. Many of them show 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. Numerous forms and varieties of C. racemosa are listed, but further studies are needed to clarify their exact phylogenetic relationships.
Regarding biology, in the Mediterranean, growth begins in April, when new stolons develop and erect branches begin to grow, and continues until December, after which the plants decline and become dormant.
As mentioned, C. racemosa reproduces vegetatively by fragmentation. When pieces of the plant break off, they develop into new plants. Small pieces of tissue only a few millimeters in diameter are able to do this.
C. racemosa can also reproduce sexually and in doing so shows holocarpy. This means that all the cytoplasm of the organism is used in the creation of gametes and only a single envelope remains at the site of the original plant. The plants are monoecious with male and female gametes produced by the same plant and released into the water column where they unite to give spherical zygotes. These settle and after five weeks produce germ tubes that elongate and branch to develop into new plants.[8] Mass spawnings sometimes occur in the Caribbean Sea and normally occur just before dawn. There were 39 such mass spawnings during a 125-day period and the days on which they occurred showed no relationship to tidal or lunar cycles. The gametes remain motile for about 60 minutes. Mass spawning is advantageous to the plant as it increases the chances of fertilization. Underwater visibility can be reduced to less than a meter by the green cloud produced in the process. Similar mass spawnings occur in the Mediterranean Sea, causing a cloud of green gametes to be released into the water about 14 minutes before sunrise.
Ecologically, Caulerpa species contain cytotoxic secondary metabolites, of which caulerpenyne is the most abundant. These prevent animals from consuming plants. A study was conducted on herbivores grazing on meadows of the invasive C. cylindracea in the northwest of its Mediterranean range. Gilt-head breams Boops boops and Sarpa salpa were found to feed on the algae, as were sea urchins Paracentrotus lividus and Sphaerechinus granularis. Other herbivores also grazed occasionally, but the total amount consumed was offset by the rapid growth of the plant and it was thought that these organisms would not play a valuable role in biocontrol of the plant. C. taxifolia and C. racemosa show the great influence of the substrate on their spatial distribution with a high colonization of the dead matte of the seagrass Posidonia oceanica
C. racemosa and C. taxifolia are both invasive Lessepsian migrants. The caulerpenyne content is lower in C. racemosa than in C. taxifolia.
Like the closely related C. lentillifera, C. racemosa is edible. It is widely consumed in salads in Japan, Fiji, the Philippines and Thailand. It is also consumed by local fishermen in Malaysia and Indonesia. These algae are rich in fiber, protein, minerals (calcium and magnesium), folic acid, ascorbic acid, vitamin A and vitamin B1, but are also low in fat.
In addition to nutritional qualities, C. racemosa also has antibacterial and antioxidant properties, but these characteristics have not yet been fully explored. These diverse biological activities offer a glimpse of biomedical innovations for the future. The properties are believed to derive from a strain of rare endophytic actinomycetes that live in symbiosis with C. racemosa and more specifically from the secondary metabolites produced (flavonoids and alkaloids). Extracts of C. racemosa have already been tested to reduce several types of cancer but also to fight against multidrug-resistant uropathogens (such as K. Pneumoniae and P. aeruginosa). Multidrug resistance is a major public health problem because by 2050 (World Health Organization WHO), 10 million people could die each year due to this evolution of bacteria against current families of antibiotics. In addition, a multitude of potential treatments have been identified for various pathologies, in particular for diabetes and herpes.
Preparation Method –
Caulerpa racemosa is a seaweed that, as mentioned, is widely consumed in the preparation of salads. This use is widespread especially in Japan, Fiji, the Philippines and Thailand.
In some countries, such as Malaysia and Indonesia, it is also consumed by local fishermen.
Guido Bissanti
Sources
– Acta Plantarum – Flora delle Regioni italiane.
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (edited by), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora d’Italia, Edagricole, Bologna.
– Treben M., 2000. Health from the Pharmacy of the Lord, Advice and experiences with medicinal herbs, Ennsthaler Editore.
Photo source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/339796762/original.jpeg
– https://upload.wikimedia.org/wikipedia/commons/8/84/Haeckel_Caulerpa_racemosa_%28uvifera%29.jpg
Warning: The pharmaceutical applications and alimurgic uses are indicated for informational purposes only, they do not represent in any way a medical prescription; therefore, any responsibility for their use for curative, aesthetic or nutritional purposes is declined.