Have you ever spotted a shiny, green sphere tucked into a crack on a reef? If so, you may have seen a sea pearl, also known as bubble algae or sailor’s eyeballs. Sea pearls (Valonia ventricosa) are one of the largest ­– if not the largest ­– single cell organisms in the world! In other words, that fluid-filled sphere is actually one giant single cell (which can be 1-5 cm in diametre, and boasts multiple nuclei)!

Generally, macroalgae like sea pearls are classified into three categories: Green, Brown, or Red Algae. An algae’s classification is not based explicitly on the coloir of the algae, but rather on their predominant photosynthetic pigment, a substance that absorbs light.

Sea Pearl is a Green Algae, which means that it falls into the Phylum Chlorophyta. All Green Algae contain the same accessory pigment, Chlorophyll b, which broadens the range of light that can be used in photosynthesis. More light absorption = more food!

The colour of a Sea Pearl typically ranges between green to dark green, and it is determined by the quantity of chloroplasts. Sea pearls reproduce by splitting into two daughter cells or by forming new bubbles from the rhizoids. But little is known about their mode of sexual reproduction.

Sea pearls can be found in subtropical and tropical tidal zones throughout much of the world. Two other species of Valonia found in the Caribbean include: elongated sea pearl (Valonia macrophysa), which tend to be smaller, longer and grow in mat-like clusters, and 2) creeping bubble alga (Valonia ulticularis). creeping bubble alga is the smallest and the least common of the three species mentioned.

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