A Bryozoan Lives in the Greenhouses

Photo is of a bryozoan attached to a 1/2″ aquaculture netting to show its size.

During the last few months, we have noticed a number of these bryozoan creatures (it turns out plural is appropriate as you’ll learn below) pictured above in some of our vats in Greenhouse 2 which mainly houses livebearers and shrimp. The photo shows the largest we’ve found. The netting it is (they are) growing on has ½ inch mesh which shows the size of this one.

I took the photo and immediately emailed Matt Hill a taxonomist with EcoAnalysts, Inc. in Moscow, Idaho for his thoughts. He emailed back saying,

“Looks like a bryozoan (“moss animal”) colony to me.  Bryozoa are colonial, filter-feeding animals, sort of like a coral. I’d be happy to squint at if you want to send some up.”

I do plan to send one to him to see if we can get the species or at least genus identified.

This isn’t the first unexpected organism we’ve found in our greenhouse systems. Our greenhouses form ecosystems and some species colonize them without our intervention and form permanent breeding populations. These include plants and animals like (links after the species names are to blogs I’ve written):

1. Pond Snail (Who knows what species.)
2. Red Ramshorn Snail (From the snail family Planorbidae.)
3. Malaysian Trumpet Snail (Probably Melanoides tuberculatus. This snail is a pain, literally. They clog up overflow strainers and when you try to clear the clog with your finger, your finger is sliced up by their pointy shells.)
4. Fingernail Clam (Sphaerium corneum) (Fingernail Clams – Sphaerium corneum and Update on Fingernail Clams – Sphaerium corneum)
5. Dragonflies (more than one species)
6. Damselflies (more than one species)
7. Mosquitos (more than one species) (Raising Mosquito Larvae for Fish Food)
8. Midge/Bloodworm (probably more than one species)
9. Diamondback Water Snake (Nerodia rhombifer)
10. Texas Ribbon Snake (Thamnophis proximus)
11. Green Tree Frog (Was Hyla cinerea, but itis.gov, our go to source for valid scientific names, says it is Dryophytes cinereus)
12. Squirrel Tree Frog (Was Hyla squirella but gov says it is Dryophytes squirellus)
13. Gray Tree Frog (Was Hyla chrysoscelis but gov says it is Dryophytes chrysoscelis)
14. Gray Tree Frog (Was Hyla versicolor but gov says it is Dryophytes versicolor)
15. Duckweed (Lemna minor) (Duckweed and Chickens)
16. Sedge (A wicked grass that cuts your hands when you try to pull it.)
17. Mint (Which one I don’t know. We planted a number of mints around the farm. One decided it liked the greenhouses.)
18. Several unidentified weeds (one with nice pink flowers)

Other species have invaded the greenhouses, but haven’t established breeding populations. These include:

1. Redear slider (Trachemys scripta elegans)
2. Bullfrog (Was Rana catesbeiana but is apparently now Lithobates catesbeianus)
3. Biting flies (Who knows what species, but they are relentless biters.)
4. Great Egret (Ardea alba. Only one, but was difficult to catch and very unfriendly when caught.)
5. Raccoons (Procyon lotor. Raccoons are listed as not having established a breeding population, although a family lived in the space between two layers of pond liner forming the walls of Greenhouse 1.)
6. Possums (Didelphis virginiana) (Attic Monster)
7. Coralsnake (Micrurus tener)
8. Texas Toad (Bufo speciosus)

As you can see from these two lists, the greenhouses have a vibrant ecology.

Back to the bryozoans. After hearing back from Matt, I did some online research on bryozoans. Much of the information comes from https://animaldiversity.org/accounts/Bryozoa/. I learned:

1. Bryozoa belong to their own phylum (plural phyla) remarkably named “Bryozoa” and are commonly known as “moss animals.” According to Wikipedia: “Depending on definitions, the animal kingdom Animalia or Metazoan contains approximately 32 phyla, the plant kingdom Plantae contains about 14, and the fungus kingdom Fungi contains about 8 phyla.” I seem to remember far fewer phyla long ago in high school and college biology.
2. There are about 5,000 currently recognized species and a similar number of extinct species (those fossils must be strange).
3. Almost all are sessile, colonial organisms.
4. They sort of resemble soft coral polyps with a ring of cilia-lined tentacles. The cilia are used to generate currents to gather plankton to eat.
5. There are three Bryozoa classes:
   1. Phylactolaemata,
   2. Stenolaemata, and
   3. Gymnolaemata.
6. Most bryozoans are marine, but brackish and freshwater species are known (obviously, since we have one).
7. Colonies usually grow on hard surfaces (ours grow on most anything including the plant hornwort [Ceratophyllum demersum]).
8. An individual bryozoan is small, about 0.5 mm (0.01968503937007874 inches, just kidding, ~0.02 in.) in length. An individual bryozoan is called a “zooid” (Now you are ready in case this comes up in a game of Trivia! You never know, we were playing a game once where the answer was Teiidae, the family to which Tegu lizards belong. I knew the answer!).
9. Colony sizes range from 1 cm (~0.4 in.) to over a meter (~1 yard).
10. Colonies form gelatinous blobs, bushy or tree-like forms, and encrusting species that resemble small corals.
11. From the above source, “Zooids within a colony may be polymorphic and specialized. All colonies have autozooids, which are responsible for feeding and digestion; the rest of the zooids in the colony are known as heterozooids and cannot feed. Some zooids, known as kenozooids, are greatly reduced and used for attachment to substrates. Others, known as varicularia, have sharp, well-developed opercula (avicularia) to defend the colony. There also may be vibracula, which have a flagellular operculum used for cleaning, or ooecia, which are specialized for brooding eggs. (Brusca and Brusca, 2003; Buchsbaum, et al., 1987; McKinney and Jackson, 1989)”
12. Also, from the above source, “A bryozoan colony begins with a single individual, known as an ancestrula. Ancestrulas are sexually produced, but colonies grow through asexual reproduction. Breeding is somewhat regulated by water temperatures and levels of sunlight: rising temperatures and increased light trigger phytoplankton growth which, in turn, triggers budding and, to a lesser extent, sexual reproduction. Species may free-spawn or, more often, females will brood eggs for at least a short time. Larvae of brooding species settle much more quickly following hatching, as their larval forms cannot feed. (Brusca and Brusca, 2003; “Introduction to the Bryozoans”, 2011)”

That’s probably enough about Bryozoa. If you want more information, try the link above. It goes on and on about them.

During my research I found this site and a statement that piqued my interest:

http://lifeinfreshwater.net/freshwater-bryozoans/ “Bryozoans occur in both still and running waters. Their presence indicates good water quality.”

This provides validation that our plant-filtered, recirculation systems work as designed. Here’s a blog I wrote that provides some description of our systems: Monster Plant, Dieffenbachia Species. I also wrote an article about our systems for Tropical Fish Hobbyist magazine called: Plant Filtration – No Water Changes (see: http://www.tfhdigital.com/tfh/201004/?pg=1#pg1). You’ll need to be a subscriber to read it. I need to review the contract with TFH to see if I have any publishing rights to the article. If not, one of these days, I’ll write an update for our Newsletter (to subscribe to our free Newsletter go to: Goliad Farms Newsletter Subscription Form).

If I get around to sending a sample to Matt Hill and he is able to identify this bryozoan, I’ll do a follow up blog.

Good fishkeeping!