Sailor's eyeball (Valonia ventricosa)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Plantae · Phylum: Chlorophyta · Class: Ulvophyceae · Order: Cladophorales · Family: Valoniaceae · Genus: Valonia.

Accepted name: Valonia ventricosa · Authority: J.Agardh, 1887 · Taxonomic status: accepted · AphiaID: 211680.

Synonyms and superseded combinations recorded for this taxon: Ventricaria ventricosa (J.Agardh) J.L.Olsen & J.A.West, 1988.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=211680 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (SeaLifeBase)

Measured values published by SeaLifeBase for Valonia ventricosa. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Depth range: 0–108 m · Habitat zone: epiphytic · Aquarium trade: never/rarely.

SeaLifeBase notes: Occurs in shallow, high-relief spur and groove zones (Ref. 87158), sands, rocks, coral rubble and corals, outer ridge of coral reef, lee side of reef crest, mangrove roots and among Thalassia . Depth varies from intertidal to shallow to until 9 m (Ref. 87157).

Source: SeaLifeBase species summary (SpecCode 139981) — https://www.sealifebase.se/summary/Valonia-ventricosa.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

2,891 georeferenced occurrence records for Valonia ventricosa are published through GBIF from 85 countries or marine areas. The map above plots 430 distinct locations from a sample of 2,891 records, omitting 83 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: Puerto Rico (510); United States of America (398); Australia (193); France (156); Mexico (119).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 5273075) — https://www.gbif.org/occurrence/search?taxon_key=5273075&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=211680 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Description and natural history (Wikipedia)

Valonia ventricosa has a coenocytic structure with multiple nuclei and chloroplasts. This organism possesses a large central vacuole that is multilobular in structure (lobules radiating from a central spheroid region).

The entire cell contains several cytoplasmic domains, with each domain having a nucleus and a few chloroplasts. Cytoplasmic domains are interconnected by cytoplasmic "bridges" that are supported by microtubules. 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.

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 ocean throughout the world, often living in coral rubble.

The greatest observed depth for viability is approximately 80 m.

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 chloroplasts of the specimen. The extremely smooth surface of the cell shines like glass when clean.

Valonia ventricosa is among the largest known single-celled organisms. Its thallus consists of a thin-walled, tough, multinucleate cell with a diameter that ranges typically from 1 to 4 cm, although it may achieve a diameter of up to 5.1 cm in rarer cases. The "bubble" alga is attached by rhizoids to the substrate fibers.

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 has been 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 study of the cellulose lattice and its orientation in biological structures, Valonia ventricosa has undergone extensive X-ray analytical procedures. It has also been studied for its electrical properties because of its unusually high electrical potential relative to the seawater that surrounds it.

Valonia ventricosa is considered a pest by some aquarium owners, as it can reproduce quickly and potentially endanger the health of fish or other organisms.

Source: Wikipedia: Valonia ventricosa — https://en.wikipedia.org/wiki/Valonia_ventricosa (CC BY-SA 4.0). Accessed 2026-09-23.

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