Yesterday's challenge wasn't all that hard. There were a number of good clues here.
I'd said "In around 30 feet of water (10 m), I found several instances of this... "
General world knowledge tells you that this is something in a tropical reef, and it occurs not too deeply.
I also gave you a few clue words: "spheres" and calling them "pearly." I wanted to say that because the opalescence doesn't quite come across in the photos.
When I started this search, I really didn't have any clue what they were. I figured they were some kind of algae, but that was a pure guess. The ocean has all KINDS of mysterious creatures in it, ones that defy your normal terrestrial boundaries.
So I started this search as several others did. I used "plant" rather than "algae" since I really wasn't very sure:
[ spherical reef plant ]
And that was enough to get me to a page on "Coral reef plants" which mentions "...Grape algae (Valonia ventricosa) - this odd algae grows in a spherical form with peg-like attachments that fasten it to a hard surface..."
In this case, it was the text, rather than the image that caught my attention. I'd described it as "spherical" because it (and the pearly quality) were the most striking characteristics. I figured that anyone writing about it would comment on that.
So I next looked up the scientific name, Valonia ventricosa, and I knew I had the answer. The Knowledge Panel (see below) had an image that was striking.
Valonia ventricosa, also known as "bubble algae" and "sailors’ eyeballs" (a remarkably vivid common name) is a species of oceanic algae around the world in tropical and subtropical regions.
Even more amazing: These things are single cells, one of (perhaps THE) largest single cell organism around.
Clicking on the Wikipedia entry, I read a bit about them, and then, as I often do, I clicked through the links on the article.
The first link was broken. It was a link to: http://www.allatsea.net/article/October_2008/Gazing_Balls_in_the_Sea
I thought this might be an interesting article, so I did a query to see if that article was still on that website:
[ site:www.allatsea.net Gazing_Balls_in_the_Sea ]
Sure enough, it's still there (I should go fix up the Wikipedia entry to reflect this). And it IS an interesting article. These things are also called "sea pearls" (makes sense), AND the article mentioned "...Ventricaria ventricosa, or Valonia ventricosa..."
Well.. that's interesting. Two names for the same plant?
I kept following up the other links (and found other problems), but was impressed when I followed the last link on the Wikipedia article, a reference to the AlgaeBase site. The link is to the AlgaeBase description of the "sailor's eyeballs."
This is pretty clearly the definitive site for questions about algae. And here you can see the story.
The original publication describing this plant was published in:
Agardh, J.G. (1887). Till algernes systematik. Nya bidrag. (Femte afdelningen.). Acta Universitatis Lundensis 23(2): 1-174, 5 plates.
If you're curious, you can see the original publication. (PDF) This is the way science used to operate--it's in Latin. It's long text passages. There are a few lovely sketches at the end.
But what's with the two names?
The original name was given by J. Agardh in the late 19th century. But as AlgaeBase points out: “This name, Ventricaria ventricosais, currently regarded as a taxonomic synonym of Valonia ventricosa."
Renaming and reclassification happens all the time. What USED to be called a brontosaurus is now called an apatosaurus. A similar thing happened here. A newer publication came out put Valonia into a new category, Ventricaria.
In that paper, Olsen and West point out that our favorite algae actually belongs to a newly described genus that they call Ventricaria. If you look at publications since 1988, they all (well, nearly all) use the new name.
http://www.reefkeeping.com/issues/2002-02/hcj/feature/ -- tells that it’s a problem
1. What IS that thing? Answer: Ventricaria ventricosa, previously known as Valonia ventricosa. Common names: bubble algae, sailor's eyeballs, sea pearls.
The second question asked how to control it. To answer this, I thought I'd try asking an easy query:
[ bubble algae aquarium problem ]
That took me to http://www.reefkeeping.com/issues/2002-02/hcj/feature/ which has a long, really interesting article with more information about Valonia / Ventricaria (including great photos of other forms of the algae).
It ALSO has a long section about controls, including the use of snails and crabs to eat them. In particular, the article mentions the crab Mithrax sculptus (aka "green" or "emerald" crab) as a way to control the spread of bubble algae in your tank.
2. What biological agent might you use to control them in your salt water aquarium? Answer: You might try using a crab in your tank to eat up the bubble algae.
However, not everything is perfect.
3. (Extra credit) Why does it now seem that the use of this biological agent might be a really bad idea?
The Reefkeeping.com article also mentions that the crabs, as they dine, might well end up spreading spores from the interior of the bubble, and end up making matters worse. You start with one algal cell, but end up with them infesting the tank.
I also checked on Google Scholar for:
[ emerald crab control bubble algae ]
And found this interesting article that confirms what we read at ReefKeeping: Efficiency of using emerald crabs Mithraculus sculptus to control bubble alga Ventricaria ventricosa (syn. Valonia ventricosa) in aquaria habitats (see (2) below). "...as the crab tears the algal cell apart, the cell liquid that contains juvenile cytoplasmatic spheres is released into the water; this behaviour might contribute to algal dispersal and consequently algal infestation. These results seem to indicate that M. sculptus might not be such an efficient bio-controller of the pest V. ventricosa as previously thought..."
Hope you enjoyed this as much as I did!
Tomorrow, the resolution of the parrotfish problem!