''Valonia ventricosa'', also known as bubble algae, sea grape or sailor's eyeballs is a species of

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

found in

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...

s throughout the world in

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...

regions, within the phylum Chlorophyta. It is one of the largest known

unicellular organism A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...

s, if not the largest. Valonia ventricosa in the Red Sea

Characteristics

''Valonia ventricosa'' has a

coenocytic A coenocyte () is a multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis, in contrast to a syncytium, which results from cellular aggregation followed by dissolution of the cell membranes insid ...

structure with multiple nuclei and chloroplasts. This organism possesses a large central

vacuole A vacuole () is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic mo ...

which is multilobular in structure (lobules radiating from a central spheroid region). The entire cell contains several

cytoplasmic In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. Th ...

domains with each domain having a nucleus and a few chloroplasts. Cytoplasmic domains are interconnected by cytoplasmic "bridges" that are supported by

microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 an ...

s. The peripheral cytoplasm (whose membrane is overlaid by the cell wall), is only about 40 nm thick. ''Valonia ventricosa'' typically grow individually, but in rare cases they can grow in groups.

Environment

They appear in tidal zones of tropical and subtropical areas, like the Caribbean, north through Florida, south to Brazil, and in the Indo-Pacific. Overall, they inhabit every

throughout the world, often living in coral rubble. The greatest observed depth for viability is approximately .

Physiology and reproduction

The single-cell organism has forms ranging from spherical to ovoid, and the color varies from grass green to dark green, although in water they may appear to be silver, teal, or even blackish. This is determined by the quantity of

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...

s of the specimen. The surface of the cell shines like glass when clean due to being extremely smooth with no texture. ''Valonia ventricosa'' is among the largest known single-celled organisms. Its

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...

consists of a thin-walled, tough, multinucleate cell with a diameter that ranges typically from although it may achieve a diameter of up to in rarer cases. The "bubble" alga is attached by rhizoids to the substrate fibers. Reproduction occurs by segregative

cell division Cell division is the process by which a parent cell (biology), cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukar ...

, where the multinucleate parent cell makes child cells, and individual rhizoids form new bubbles, which become separate from the parent cell.

Studies

''Valonia ventricosa'' has been studied particularly because the cells are so unusually large that they provide a convenient subject for studying the transfer of water and water-soluble molecules across biological membranes. It was concluded that the properties of permeability in both osmosis and diffusion were identical, and that urea and formaldehyde molecules did not require any kind of postulated water-filled pores in the membrane to move through it. In studying the cellulose lattice, and its orientation in biological structures, ''Valonia ventricosa'' has undergone extensive

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

analytical procedures. It has also been studied for its electrical properties, due to its unusually high electrical potential relative to the seawater that surrounds it.

References

External links