Valonia ventricosa

Valonia ventricosa, also known as "bubble algae" and "sailors’ eyeballs", is a species of algae found in oceans throughout the world in tropical and subtropical regions. It is one of the largest single-celled organisms. However, although genuinely a single cell, it has more than one nucleus.The references use the word "multinucleate", without specifying number.

Characteristics
Environment
Valonia ventricosa usually grow alone, but sometimes they grow in groups. They appear in the littoral zones and continental shelf of tropical and subtropical areas, like the Caribbean, north to Florida, south to Brazil, and in the Indo-Pacific. Overall, they inhabit most oceans in the world,Overview occurrence, Valonia ventricosa, GBIF, accessed 27 August 2010 often living in broken coral.
The deepest water it lives in is about .

Physiology and reproduction
The single-cell organism has a spherical to ovoid (egg-like) shape. The colour varies from grass green to dark green (though in deep dark water they may appear to be silver, teal, or even blackish). This is determined by the number of chloroplasts of the specimen. The surface of the cell shines like glass. The body is a thin-walled, tough, single cell with more than one nucleus. The diameter is usually from  although it may get to  in rare cases. The "bubble" alga is attached to the bottom by fibres: "... anchored to a substrate by minute hair-like appendages called rhizoids that create a surprisingly strong hold". 

Reproduction occurs by cell division, where the multinucleic mother cell makes daughter cells, which become separate from the mother cell.

Studies
Because its cells are so large, Valonia ventricosa has been used to study the permeability of cell membranes.< In studying the cellulose lattice in the cell wall, Valonia ventricosa has undergone extensive X-ray 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 

Other websites

Category:Algae