WTF is That? Valonia ventricosa

Today we are going to explore the strange and alien Valonia ventricosa, or the Sailor’s Eye. You may remember your first days diving on the coral reefs, watching all the fish and exploring the benthos. At some point in your underwater adventures you probably stumbled upon what looked to be a bit of treasure. Maybe it’s a ball of silver, or some sort of jewelry bead for giants. If you would have touched it (which hopefully you didn’t) it would have collapsed like a deflated balloon, leaving you wondering is this is something from the reef, or from the humans above?

What is Valonia ventricosa?

Valonia ventricosa is actually a type of green algae which is found throughout the shallow seas of the tropical oceans, and is actually one of the largest single celled organisms on earth. Like other plants, the cell wall of the algae is composed of cellulose, however in V. ventricosa the cellulose crystals are quite unique, which give the plant its shiny, silver color. It has multiple nuclei, which are arranged in lobes radiating out from the center of the bubble, which is called a vacuole. Its internal anatomy looks something like a Tesla plasma ball, which you may find in science or novelty shops. Unlike other members of its genera, often called bubble algae, V. ventricosa is a solitary organism which generally reproduces through asexual processes which result in the formation of daughter colonies.

The History of V. venticosa

Because of their large cell size and unique function, they have been studied for over a hundred years by cell biologists and electrophisiologists to understand ion transport, cellulose crystallization, membrane formation, and much more to relate how these processes work within cells. Although there are over 2,000 published scientific papers on the species, almost nothing is known about their ecological role. According to the information we could find, there are no listed herbivores known to eat them, and it is unknown how they affect other organisms growing around them, such as corals. We do know from citizen science data that they are most prevalent in the warm summer months, and their abundance decreases greatly during colder, monsoon seasons. It is still unknown how they reproduce sexually, although it is assumed that they do at some point.
There is still so much to know about these unique plant cells, and although we now know they are not treasure, we will continue to value them as an indicator of the incredible diversity of life on our planet, and as a testament to how little we truly understand about the networks and interactions of life in the oceans.