''Caulerpa racemosa'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of edible

green alga The green algae (: green alga) 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 ( ...

, a

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

in the family

Caulerpaceae Caulerpaceae is a family of green algae in the order Bryopsidales Bryopsidales is an order of green algae, in the class Ulvophyceae. It is a diverse group of mostly marine macroalgae. Characteristics The thallus is filamentous, highly branch ...

. It is commonly known as sea grapes (along with the related ''

Caulerpa lentillifera ''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 ...

'') and is found in many areas of shallow sea around the world. Despite the name, it is not related to

grapes A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began approximately 8,0 ...

. 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 An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

Taxonomy

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 In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

. A number of forms and varieties for ''C. racemosa'' are listed but further study is needed to clarify their exact

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

relationships.

Description

A plant of ''C. racemosa'' consists of a number of branches linked to

stolon In biology, a stolon ( from Latin ''wikt:stolo, stolō'', genitive ''stolōnis'' – "branch"), also known as a runner, is a horizontal connection between parts of an organism. It may be part of the organism, or of its skeleton. Typically, animal ...

s which are anchored to the sandy

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

rhizoid Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be un ...

s. The branches are a few centimetres apart and can grow to a height of . Many spherical or ovate side-shoots branch off these and give the seaweed its name of sea grapes.Sea grapes (''Caulerpa racemosa'')
''Marine Species Identification Portal''. Retrieved 2011-08-20. Like other members of the order

Bryopsidales Bryopsidales is an order of green algae, in the class Ulvophyceae. It is a diverse group of mostly marine macroalgae. Characteristics The thallus is filamentous, highly branched, and may be packed into a mass. It is coenocytic, having multi-nu ...

, each ''C. racemosa'' plant consists of a single enormous cell with a large number of nuclei. The

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s containing

chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...

are free to migrate from any part of the organism to another and there is a network of fibrous proteins that helps movement of

organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as Organ (anatomy), organs are to th ...

s.The Cell Biology of the Bryopsidales
Retrieved 2011-08-18

Distribution

''C. racemosa'' is widely distributed in shallow temperate and tropical seas. In 1926 a new form of the alga was reported off

Tunisia Tunisia, officially the Republic of Tunisia, is a country in the Maghreb region of North Africa. It is bordered by Algeria to the west and southwest, Libya to the southeast, and the Mediterranean Sea to the north and east. Tunisia also shares m ...

, possibly an immigrant from the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

, and this later spread to much of the eastern

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

. In 1990, a new, larger form with two vertical rows of branches on opposite sides of the stem was found off

Libya Libya, officially the State of Libya, is a country in the Maghreb region of North Africa. It borders the Mediterranean Sea to the north, Egypt to Egypt–Libya border, the east, Sudan to Libya–Sudan border, the southeast, Chad to Chad–L ...

. It spread widely, invading much of the Mediterranean Sea and becoming more widespread than the invasive species, ''

Caulerpa taxifolia ''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 ...

''. It is known as var. ''cylindracea'' and may have originated from Australian waters. In America ''C. racemosa'' is found in shallow water in the

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

, around

Bermuda Bermuda is a British Overseas Territories, British Overseas Territory in the Atlantic Ocean, North Atlantic Ocean. The closest land outside the territory is in the American state of North Carolina, about to the west-northwest. Bermuda is an ...

and along the eastern seaboard of America from

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Biology

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.Grazing on ''Caulerpa racemosa'' var. ''cylindracea'' (Caulerpales, Chlorophyta) in the Mediterranean Sea by herbivorous fishes and sea urchins.
Retrieved 2011-08-22. ''C. racemosa'' reproduces

vegetatively Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is a form of asexual reproduction occurring in plants in which a new plant grows from a fragment or Cutting (plant), cutting of the parent pl ...

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. ''C. racemosa'' can also reproduce sexually and in so doing exhibits holocarpy. This means that all the organism's

cytoplasm The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...

is used up in the creation of the

gamete A gamete ( ) is a Ploidy#Haploid and monoploid, haploid cell that fuses with another haploid cell during fertilization in organisms that Sexual reproduction, reproduce sexually. Gametes are an organism's reproductive cells, also referred to as s ...

s and only a husk remains at the site of the original plant. The plants are

monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system comparable with gynomonoecy, andromonoecy and trimonoecy, and contras ...

with male and female gametes being produced by the same plant and liberated into the water column where they unite to give spherical

zygote A zygote (; , ) is a eukaryote, eukaryotic cell (biology), cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individ ...

s. These settle and after five weeks produce

germ tube A germ tube is an outgrowth produced by spores of spore-releasing fungi during germination. The germ tube differentiates, grows, and develops by mitosis to create somatic hyphae.C.J. Alexopolous, Charles W. Mims, M. Blackwell, ''Introductory My ...

s which elongate and branch to develop into new plants. Mass spawnings sometimes take place in the

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. 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. 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.

Ecology

''Caulerpa'' species contain secondary metabolites that are

cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are toxic metals, toxic chemicals, microbe neurotoxins, radiation particles and even specific neurotransmitters when the system is out of balance. Also some types of dr ...

, of which caulerpenyne is the most abundant. These deter animals from consuming the plants. A study has been done on

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s that graze on meadows of the invasive '' C. cylindracea'' in the north west of its range in the Mediterranean. The

sea bream Sparidae is a family of ray-finned fishes belonging to the order Spariformes, the seabreams and porgies, although they were traditionally classified in the order Perciformes. The over 150 species are found in shallow and deep marine waters in te ...

s ''

Boops boops ''Boops boops'' ( ; from Ancient Greek , ), commonly called the boce, bogue, or bogue bream, is a species of seabream native to the eastern Atlantic. Taxonomy In the fourth century BCE, ''Boops boops'' was documented by Aristotle as () in his ...

'' and ''

Sarpa salpa The salema porgy (''Sarpa salpa''), also known as the dreamfish, salema, cow bream, karanteen, salpa, saupe, strepie or goldline, is a species of marine ray-finned fish belonging to the family Sparidae, which includes the seabreams and porgies. I ...

'' were found to feed on the algae, as did the

sea urchin Sea urchins or urchins () are echinoderms in the class (biology), class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal zone to deep seas of . They typically have a globular body cove ...

s ''

Paracentrotus lividus ''Paracentrotus lividus'' is a species of sea urchin in the family Parechinidae commonly known as the purple sea urchin. It is the type species of the genus and occurs in the Mediterranean Sea and eastern Atlantic Ocean. Description ''Paracentr ...

'' and ''

Sphaerechinus granularis ''Sphaerechinus granularis'' is a species of sea urchin in the Family (biology), family Toxopneustidae, commonly known as the violet sea urchin, or sometimes the purple sea urchin (though the latter is also a common name for a Pacific sea urchin ...

''. Other

s 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. ''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'' ''C. racemosa'' and '' C. taxifolia'' are both invasive

Lessepsian migrant The Lessepsian migration (or Erythrean invasion) is the migration of marine species along the Suez Canal, usually from the Red Sea to the Mediterranean Sea, and more rarely in the opposite direction. When the canal was completed in 1869, fish, ...

s. Caulerpenyne content is lesser in ''C. racemosa'' than in ''C. taxifolia''.

Uses

Like the closely related '' C. lentillifera'', ''C. racemosa'' is edible. It is consumed widely in salads in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Fiji Fiji, officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists of an archipelago of more than 330 islands—of which about ...

, the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

, and

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

. It is also eaten by local fishermen in

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

and

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

. They are rich in fiber, proteins, minerals (calcium and magnesium),

folic acid Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...

ascorbic acid Ascorbic acid is an organic compound with formula , originally called hexuronic acid. It is a white solid, but impure samples can appear yellowish. It dissolves freely in water to give mildly acidic solutions. It is a mild reducing agent. Asco ...

vitamin A Vitamin A is a fat-soluble vitamin that is an essential nutrient. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinyl esters, and several provitamin (precursor) carotenoids, most not ...

, and

vitamin B1 Thiamine, also known as thiamin and vitamin B1, is a vitamin – an essential micronutrient for humans and animals. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thia ...

while also being low in fat. 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. 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 An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; ...

actinomycetes The Actinomycetales is an Scientific classification, order of Actinomycetota. A member of the order is often called an actinomycete. Actinomycetales are generally Gram-positive bacteria, gram-positive and anaerobic and have mycelia in a filamento ...

that lives in

symbiosis Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biological interaction, between two organisms of different species. The two organisms, termed symbionts, can fo ...

with ''C. racemosa'' and more particularly of the

secondary metabolites Secondary metabolites, also called ''specialised metabolites'', ''secondary products'', or ''natural products'', are organic compounds produced by any lifeform, e.g. bacteria, archaea, fungi, animals, or plants, which are not directly involved ...

produced (

flavonoids Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

and

alkaloids Alkaloids are a broad class of naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large variety of organisms i ...

). Extracts of ''C. racemosa'' are already tested to reduce different types of

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

but also to fight against

multi-drug resistant Multiple drug resistance (MDR), multidrug resistance or multiresistance is antimicrobial resistance shown by a species of microorganism to at least one antimicrobial drug in three or more antimicrobial categories. Antimicrobial categories are ...

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 An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...

. Moreover, a multitude of potential treatments for various pathologies have been identified, particularly for

diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...

and

herpes Herpes simplex, often known simply as herpes, is a viral infection caused by the herpes simplex virus. Herpes infections are categorized by the area of the body that is infected. The two major types of herpes are oral herpes and genital herp ...

References

{{Taxonbar, from=Q1147907 racemosa Plants described in 1873