Caulerpa prolifera
Encyclopedia
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 dense stands on the sandy bed of shallow areas of sea.
A plant of C. prolifera consists of a number of blades or laminae linked by underground stolon
s which are fixed to the sandy substrate
by rhizoid
s. The blades contain chlorophyll for photosynthesis
though the green colour is somewhat masked by other pigments. Like other members of the order Bryopsidales
, each C. prolifera plant is an individual organism consisting of a giant single cell with multiple nuclei. Chloroplast
s are free to move from one part of the organism to another as a response to the level of light at any point and there is a network of fibrous proteins that facilitates movement of organelle
s. Even when derived from the same source, individual plants of C. prolifera show great variability of form and it has been shown that this is in part related to the level of light. In bright locations, plants are compact, highly branched and dense, while in shady locations, populations typically have blades that are longer and thinner and can more efficiently make use of the limited light available.
Two distinct forms of the alga are recognised, Caulerpa prolifera f. obovata (J.Agardh) and Caulerpa prolifera f. zosterifolia (Børgesen).
es to colonize the area. C. prolifera grows rapidly with growth taking place at night at the tips of blades and stolons. At dawn, the new tips are white, but during the day chloroplasts move in to the newly available space. If parts of the plant become covered in sediment, chloroplasts can be withdrawn and moved to more productive parts.
Under normal conditions, asexual reproduction
occurs by fragmentation of the plant. Pieces of tissue only a few millimetres across are capable of growing into new plants.
Less usually, C. prolifera may undergo sexual reproduction by holocarpy. This may occur under conditions of stress with the entire cytoplasm undergoing gametogenesis
and the original organism being left as a husk. Such conditions occurred in 2005 after the passage of Hurricane Wilma
over a lagoon in the Caribbean Sea
. On that occasion, there was a synchronous spawning of C. prolifera and many other siphonous green algae
. Besides turbulent water movement, the hurricane caused the sea temperature to drop from 29 to 19°C in a few hours. This thermal anomaly seems to have triggered the mass spawning.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of green alga, a seaweed
Seaweed
Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
in the family Caulerpaceae
Caulerpaceae
In taxonomy, the Caulerpaceae are a family of algae, specifically of the Bryopsidales....
. It is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus Caulerpa
Caulerpa
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...
, the type location being Alexandria
Alexandria
Alexandria is the second-largest city of Egypt, with a population of 4.1 million, extending about along the coast of the Mediterranean Sea in the north central part of the country; it is also the largest city lying directly on the Mediterranean coast. It is Egypt's largest seaport, serving...
, Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
. It grows rapidly and forms dense stands on the sandy bed of shallow areas of sea.
Description
Stolon
In biology, stolons are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external skeletons.-In botany:...
s which are fixed to the sandy substrate
Substrate (biology)
In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...
by rhizoid
Rhizoid
Rhizoids are thread-like growths from the base or bottom of a plant, found mainly in lower groups such as algae, fungi, bryophytes and pteridophytes, that function like roots of higher plants ....
s. The blades contain chlorophyll for photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
though the green colour is somewhat masked by other pigments. Like other members of the order Bryopsidales
Bryopsidales
Bryopsidales is an order of green algae, in the class Bryopsidophyceae.-Characteristics:The thallus is filamentous and much branched and may be packed into a mass. It is coenocytic, having multi-nucleate cells consisting of cytoplasm contained within a cylindrical cell wall...
, each C. prolifera plant is an individual organism consisting of a giant single cell with multiple nuclei. Chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
s are free to move from one part of the organism to another as a response to the level of light at any point and there is a network of fibrous proteins that facilitates movement of organelle
Organelle
In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer....
s. Even when derived from the same source, individual plants of C. prolifera show great variability of form and it has been shown that this is in part related to the level of light. In bright locations, plants are compact, highly branched and dense, while in shady locations, populations typically have blades that are longer and thinner and can more efficiently make use of the limited light available.
Two distinct forms of the alga are recognised, Caulerpa prolifera f. obovata (J.Agardh) and Caulerpa prolifera f. zosterifolia (Børgesen).
Distribution
C. prolifera occurs in shallow European waters, the Mediterranean Sea and the warm eastern Atlantic Ocean and also the eastern seaboard of the United States, Mexico and Brazil, as well as certain other scattered locations.Biology
Caulerpa spp help consolidate the seabed and enable seagrassSeagrass
Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...
es to colonize the area. C. prolifera grows rapidly with growth taking place at night at the tips of blades and stolons. At dawn, the new tips are white, but during the day chloroplasts move in to the newly available space. If parts of the plant become covered in sediment, chloroplasts can be withdrawn and moved to more productive parts.
Under normal conditions, asexual reproduction
Asexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
occurs by fragmentation of the plant. Pieces of tissue only a few millimetres across are capable of growing into new plants.
Less usually, C. prolifera may undergo sexual reproduction by holocarpy. This may occur under conditions of stress with the entire cytoplasm undergoing gametogenesis
Gametogenesis
Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes. Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes,...
and the original organism being left as a husk. Such conditions occurred in 2005 after the passage of Hurricane Wilma
Hurricane Wilma
Hurricane Wilma was the most intense tropical cyclone ever recorded in the Atlantic basin. Wilma was the twenty-second storm , thirteenth hurricane, sixth major hurricane, and fourth Category 5 hurricane of the record-breaking 2005 season...
over a lagoon in the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
. On that occasion, there was a synchronous spawning of C. prolifera and many other siphonous green algae
Bryopsidales
Bryopsidales is an order of green algae, in the class Bryopsidophyceae.-Characteristics:The thallus is filamentous and much branched and may be packed into a mass. It is coenocytic, having multi-nucleate cells consisting of cytoplasm contained within a cylindrical cell wall...
. Besides turbulent water movement, the hurricane caused the sea temperature to drop from 29 to 19°C in a few hours. This thermal anomaly seems to have triggered the mass spawning.