Phylum Bryozoa
Table of Contents
Bryozoans
The ocean is a vast environment that houses a plethora of marine organisms. The organisms range from the massive blue whale to the microscopic plankton. There are so many marine organisms that can be observed and researched. Each organism has their own niche, time period in which they live/lived, and adaptations that aided their survival. Some have a footprint that isn’t washed away for a substantial period in the sands of time and some washed away quickly. The cycle of life proves to be one of constant adaptation.
A phylum of marine organisms is the bryozoans. This group of organisms was evolved in the early Ordovician period. The oldest fossil that have been collected have an age of 460 million years. The bryozoans are one of a distinct group of species that do not have any fossil record in the Precambrian period.
The word bryozoan means “moss animal” in Swedish (Fuchs, 2011). The meaning of bryozoan relates to how these organisms live in their environment. Bryozoans grow in a colonial fashion. These organisms start at a location and spread over the area of the environment to form their colonial niche The larvae settle onto a host environment such as a reef. Once the larvae settles its starts to excrete a solution that will grow to be its zooarium. The solution that secreted can be calcium carbonate or aragonite. The excreted solution flows around the polylp (individual organism) and attatches to the surface it is placed on. After attachment, the solution will start to build from the surface up. Which forms the housing unit that the organism lives in. This is the beginning stage of the process to build a colony. Bryozoans are reef-building or colonial organisms, they grow like coral reefs. Typically, these organisms build their communities in two different styles. The first encrusts themselves over an entire surface or as much as the surface that the organism can build on. In comparison, the other fashion of building their communities is a branching style. These type of bryozoans grow out like a bush or have a frondose appearance (D'Orbigny, n.d.). A frondose style of growing looks like a lattice or ladder shape, which can be demonstrated by the figures below.
The ocean is a vast environment that houses a plethora of marine organisms. The organisms range from the massive blue whale to the microscopic plankton. There are so many marine organisms that can be observed and researched. Each organism has their own niche, time period in which they live/lived, and adaptations that aided their survival. Some have a footprint that isn’t washed away for a substantial period in the sands of time and some washed away quickly. The cycle of life proves to be one of constant adaptation.
A phylum of marine organisms is the bryozoans. This group of organisms was evolved in the early Ordovician period. The oldest fossil that have been collected have an age of 460 million years. The bryozoans are one of a distinct group of species that do not have any fossil record in the Precambrian period.
The word bryozoan means “moss animal” in Swedish (Fuchs, 2011). The meaning of bryozoan relates to how these organisms live in their environment. Bryozoans grow in a colonial fashion. These organisms start at a location and spread over the area of the environment to form their colonial niche The larvae settle onto a host environment such as a reef. Once the larvae settles its starts to excrete a solution that will grow to be its zooarium. The solution that secreted can be calcium carbonate or aragonite. The excreted solution flows around the polylp (individual organism) and attatches to the surface it is placed on. After attachment, the solution will start to build from the surface up. Which forms the housing unit that the organism lives in. This is the beginning stage of the process to build a colony. Bryozoans are reef-building or colonial organisms, they grow like coral reefs. Typically, these organisms build their communities in two different styles. The first encrusts themselves over an entire surface or as much as the surface that the organism can build on. In comparison, the other fashion of building their communities is a branching style. These type of bryozoans grow out like a bush or have a frondose appearance (D'Orbigny, n.d.). A frondose style of growing looks like a lattice or ladder shape, which can be demonstrated by the figures below.
According to the taxonomic record, it is apparent that bryozoans are closely related to the brachiopods and mollusks. This may seem deceiving, but there is factual evidence to support the similarities and to note distinct differences. When comparing a brachiopod or mollusk is it very easy to see that they do not look remotely similar. So appearance isn’t where we make any connection. However, the inside of the organisms is where a line can be drawn. Both possess some form of anatomy. There are significant features that evolved in the bryozoa phylum. The formation of a gut and the mouth and anus located in separate locations. Another feature the bryozoan possessed was the ability to filter feed (McKinney and Jackson, n.d.). Filter feeding for the bryozoan occurred when the polyp extended itself out of the aperture and captured plankton in its tentacles. An interesting feature of the bryozoans is that most of the colonial species are hermaphroditic, both male and female sexes. Occasionally there are exceptions where the male and female are separated in the colony (Claus, 2013).
Anatomy (Soft and hard part)
Bryozoan anatomy can be broken down into two basic components: hard part and soft part. Each category is different enough to separate them into categories (soft and hard part). The bryozoan can be thought of a fragile organism that sits inside of a protective barrier. The organism has no defensive mechanisms that can fend off predators. So it relies on its zooecium to hide from predators. The zooecium is a calcium carbonate housing unit that the zooid can extend and retract from. Breaking down the soft part anatomy of the organism can be done from the top to the bottom.
Soft Part
On the top of a zooid sits the opening where the zooid will extend from. This opening is called the operculum. Following the operculum is an array of tentacles that extended from the tentacle crown. The purpose of having these tentacles is to feed. Bryozoans are reef building organisms and are sessile, meaning they are stationary, and they acquire food through filter feeding. By observing the second figure below, which depicts that extended form of the bryozoan that sits in its zooecium. The organism has no feature of mobility. The tentacles are lined with microscopic extensions called chilia; which are extended into the current and grasp ahold of microplankton for feeding. Under the tentacle crown is the ganglion, which is referenced to as the brain of the organism ( Buchsbaum, Jackson, and McKinney, n.d.) The next anatomical feature would be the lophophore. The lophophore is an important feature of the bryozoan, it serves many purposes. In the lophophore there are muscles that give the zooid the capability to extend and retract for feeding. The retractor muscle is the strongest muscle of the bryozoan and is housed inside the tentacle crown. Continuing further down the lophophore is where the mouth is located. The mouth processes the food that is captured by the tentacles. Which will then go down to the esophagus, through the intestines, and will complete its journey in the stomach where it will be converted into energy and other nutrients needed to sustain life.
Subsequently, the processed food will transition into waste that will need disposed of, where the anus comes into play. The anus is located directly below the lophophore and waste will exit there. Below the stomach sits the funiculus. A funiculus is a ligament that extends below the stomach and attaches to the bottom of the body wall to keep the stomach in place. And at the bottom of the organism is the retractor muscle. The retractor muscle is the strongest muscle of the bryozoan. Its purpose is to retract the lophophore and tentacle crown, this is done a quick movement. A crucial note to make when studying the soft part anatomy of a bryozoan is that the zooid is filled with fluid. The presence of fluid makes movement of muscles possible and is important communication between zooids (Waaji, n.d.). An interesting fact concerning the soft part anatomy of bryozoans is that there is no organs concerning respiration.
Subsequently, the processed food will transition into waste that will need disposed of, where the anus comes into play. The anus is located directly below the lophophore and waste will exit there. Below the stomach sits the funiculus. A funiculus is a ligament that extends below the stomach and attaches to the bottom of the body wall to keep the stomach in place. And at the bottom of the organism is the retractor muscle. The retractor muscle is the strongest muscle of the bryozoan. Its purpose is to retract the lophophore and tentacle crown, this is done a quick movement. A crucial note to make when studying the soft part anatomy of a bryozoan is that the zooid is filled with fluid. The presence of fluid makes movement of muscles possible and is important communication between zooids (Waaji, n.d.). An interesting fact concerning the soft part anatomy of bryozoans is that there is no organs concerning respiration.
In continuation of soft part anatomy of bryozoa is the reproductive portion of the zooid. Salt water bryozoa typically reproduce sexually. In the case of sexual reproduction, there two anatomical features that are needed. They are the ovaries and spermatozoa. Both of these features are found adjacent on each side of the stomach. On the other hand there is asexual reproduction that is more commonly found in freshwater bryozoa. This type of bryozoa form what are called stratoblasts. The stratoblasts are formed internally in the funniculus (Waaji, n.d.).
Hard Part
The second portion of bryozoan anatomy is the hard part of the organism, A zooarium is the feature that houses the zooid and multiply during the formation of a colony. The zooarium can be referred to as the entire colonial structure of the bryozoan community. Each zooarium has a foundation components that attribute to the structure of the housing unit. This is what is called a zooecium. Zooeciums are a tubular structure that is composed of calcium carbonate, chitin, or membranous material. In some cases the zooecium can be comprised of aragonite (Cullivier and Schurmann, 1969).
Zooarium:
Zooecium
Fossil Identification Guide
Bryozoans can be broadly classified under Kingdom: Animalia and Phylum: Bryozoa, and can be referred to as lophophores similar to brachiopods. The next classification branch under phylum is Class; the three classes are Phylactolaemata, Stenolaemata, and Gymnolaemata. Each class is unique in its own way. Phylactolaemates are freshwater bryozoans, Stenolaemates are strictly marine, and certain Gymnolaemates can be found in either freshwater or in marine environments. Following class is Order. There are five important orders of bryozoa and one minor: 1. Fenestrida, 2. Trepostomatida, 3. Cystoporida, 4. Cryptostomida, and 5. Cyclostomata (Jackson and McKinney, 1989). The minor or less recognized order is Hederellida or Cheilostomata. The final sequence is Genus/Species, there are approximately 5,000 different species of bryozoans!
Following the process of classification, the paleontologist can sort through descriptions and distinctions to identify a bryozoan. But how can one determine the specific order or genus? The best method is to look at specific qualities of the morphology of the bryozoan. And there are several ways to categorize the bryozoan down to the order or even genus. For instance, observe the shape of the aperture, how thick/thin the zooecium is or if it is tubular, whether monticules are present, and the list goes on. To avoid confusion it is easy to break down the features down to class or order for a novice paleontologist. Since there are hundreds and then thousands of possibilities when it comes to genus and species. Let’s begin with the classes then finish with the orders:
Class Gymnolaemata:
Gymnolaemates have a cylindrical zooid and a spherical aperture. The epistome is absent. With a body wall constructed of different tissues and can be composed of calcium carbonate. The zooids form in a “branching” formation and are polymorph. The coelum of each individual zooid are seperated by a septum or double wall (Ver Der Waaji. 2005,2006,2007).
http://www.seawater.no/fauna/bryozoa/images/CRW_2677.jpg http://www.snorkelstj.com/picture_library/creatures/tunicates/tan-fan-bryozoan_2507b.jpg
Class Stenostomata:
The zooids are cylindrical or flat with a circular aperture. The body walls are not calcerious, but membranous to gelatin. Also, the zooarium morphology is frondose, or lattice/ladder shaped. Their geologic range is from the Ordovician to Permian period (Ver Der Waaji. 2005,2006,2007).
http://www.uky.edu/OtherOrgs/KPS/stratigraphicfauna/ http://www.bioresurs.uu.se/myller/hav/hav_bild/mossdjur.jpg
sloansvalleymacrofauna/images/IMG_0208ac.jpg
sloansvalleymacrofauna/images/IMG_0208ac.jpg
Class Phlyacolaemata (Uncommon):
Phylaecolaemates have cylindrical shapes of their zooids. An epistome is present and the lophophore is horse-shoe shaped. The body wall is constructed of muscle tissue and is not composed of calcium carbonate (fresh water). And the coelum is continous between the zooids, similar to a “branching” direction. Branching is when the zooids grow like a tree. The divert the directions of growth and the patterns resemble that of a tree with no leaves on it (Ver Der Waaji. 2005,2006,2007). These are not found often, if they are to be found they typically appear in freshwater environments.
http://lh3.ggpht.com/_1wtadqGaaPs/TAkJxpTfSZI/AAAAAAAAEjU/ http://bugwoodcloud.org/images/384x256/5503449.jpg
amOagQPwOrI/tmp4810_thumb_thumb.jpg?imgmax=800
amOagQPwOrI/tmp4810_thumb_thumb.jpg?imgmax=800
Order Stenolaemata:
Stenolaemates appear in geologic history from the Ordovician Period and can still be found in present day. These bryozoans have a well-defined tubular structure that the zooid lives in, and has durable calcium carbonate walls. A large majority of these bryozoans lack an operculum, the hinge that opens and closes for extension to feed (Prothero, 1999). Their pattern of growth is fan-like (shown in figures below). The aperture is almost directly proportional to the size of the living area (“Stenolaemata,” 2013).
http://www.marinelife.ac.nz/species/737/1.jpg http://seanet.stanford.edu/Bryozoa/diaperof_cal580.jpg
Order Trepostomatida (Class-Stenolaemata):
Trepostomates are a common bryozoan of the Ordovician period. They often form in an “encrusting” pattern and grow in massive colonies. The have polyhonal apertures and possess tubular zooecia. These bryozoans have thin walled zooariums and will often times have monticules. Monticules are small to large “bumps” that protrude out of the walls of the organism.
https://o.quizlet.com/EEvYBOvzVGo3TI4BBdKTKQ_m.jpg http://paleo.cortland.edu/tutorial/Bryozoans/Bryozoan%20Images/trepostome1.GIF
Order Cystoporida (Class-Stenolaemata):
Cystoporates have a tubular zooecia with a circular aperture. They were present on Earth from the Ordovician to Permian period. An excellent indicator that the bryozoan the paleontologist is a cycloporate is the presence of a lunaria. A lunaria is a crescent shaped build up underneath the aperture. Another indicator that the specimen is a cystoporate is a separation or gap in the apertures. These bryozoans can be either encrusting, branching, or even frondose in respect to the dispersion of the zooids.
https://upload.wikimedia.org/wikipedia/commons/6/63/Mesonea_radians.jpg http://geokogud.info/git/specimen_image/538/preview/538-1.jpg
Order Cyclostomata (Class- Stenolaemata):
These bryozoans have a geologic range from the Ordovician period and can still be found in present day. Cyclostomates have a ciccular aperture and tubular walls. A profound way to identify this type of bryozoan is the relation to the “Aulopora”coral. The feature to consider when observing the bryozoan is the “chain-like” zooid organization.
http://www.bryozoa.net/cyclostomata/plagioeciidae/plagsar.jpg http://neogenebryozoans.myspecies.info/sites/neogenebryozoans.myspecies.info/files/PDT6300%20x.jpg
Order Cryptostomida/Cheilostomata (Class- Gymnolaemata):
Cheilostomates possess a circular aperature and a coffin-shaped zooecia. In addition, these bryozoans have an operculum. A closable and opening lid on top of the lophophore. And their geologic range is from the Jurassic Period to present day.
http://www.ncfossilclub.org/sites/default/files/imagecache/gallery_full_scaled/DSC_1437-49.jpg http://www.ncfossilclub.org/sites/default/files/imagecache/gallery_full_scaled/DSC_1410-32.jpg
Pennsylvanian Bryozoans
- South Western PA- Rhombopora and Septopora
- Northeastern PA- Lophopodella carteri
- Bradford County- Treptostomata
- Bedford County, Mann’s Quarry, and Monroe Township- Fenestella
- Uniontown- Abundance of fenestrates
- Thompson Quarry- Fenestrata
- Chalk Hill- Fenestrata
- Fayette and Somerset Counties- Fenestrata
- Chestnut Mountain/Negro Mountains- Fenestrata
- Wymps Gap- Class Stenolaemata
- Family: Rhomboporidae
- Genus: Rhombopora sp.
- Family: Sulcoreteporidae
- Genus: Sulcoretepora sp.
- Family: Hexagonellidae
- Genus: Prismopora sp.
- Genus: Septoporidae
- Septopora
- Genus: Polyporidae
- Polypora
- Genus: Acanthodadiidae
- Species: Penniretepora
- Genus: Fenestellidae
- Species: Fenestella
- Family: Rhomboporidae
- Milford- Class: Stenolaemata
- Class: Trepostomata
- Lock Haven- Stenolaemata
- Family: Amplexoporidae
- Monotrypa benjamini
- Family: Amplexoporidae
- Jonestown (Swatara Gap)- Stenolaemata
- Genus: Berenicea
- Family: Heterotrypidae
- Genus: Dekayella sp.
- Family: Halloporidae
- Genus: Parvohallopora cf. dalei
- Genus: Polyporidae
- Species: Polypora
- Girty’s Notch- Class: Stenolaemata
- Family: Sulcoreteporidae
- Sulcoretepora cf. incisurata
- Family: Sulcoreteporidae
- Amity Hall- Class: Stenolaemata
- Family: Sulcoreteporidae
- Genus: Sulcoretepora cf. incisurata
- Family: Sulcoreteporidae
- New Bloomfield- Class: Stenolaemata
- Family: Sulcoreteporidae
- Sulcoretepora cf. incisurata
- Family: Polyporidae
- Genus: Polypora sp.
- Family: Fenestellidae
- Genus: Fenestella cf. emaciata
- Genus: Fenestella cf. sinuosa
- Family: Sulcoreteporidae
- Duncannon- Class: Stenolaemata
- Family: Polyporidae
- Species: Polypora
- Family: Fenestellidae
- Genus: Fenestella cf. emaciata
- Genus: Fenestella cf. sinuosa
- Family: Polyporidae
- Rockville (Perry County)- Class: Stenolaemata
- Family: Sulcoreteporidae
- Genus: Sulcoretepora incisurata
- Family: Sulcoreteporidae
- Dromgold: Class: Stenolaemata
- Family: Sulcoreteporidae
- Genus: Sulcoretepora incisurata
- Family: Sulcoreteporidae
- Outskirts of Newport- Class: Stenolaemata
- Family: Sulcoreteporidae
- Sulcoretepora sp.
- Family: Sulcoreteporidae
- Central PA- Monotrypidae, Diplotrypidae, Trematoporidae, Halloporidae, Ceramoporidae, and Fistuliporidae
- Altoona reef- Stenolaemata
- Shippensburg- Stenolaemata (Fenestellidae and Sulcoreteporidae)
- Family: Sulcoreteporidae
- Genus: Sulcoretepora sp.
- Genus: Fenestellidae
- Fenestella
- Family: Sulcoreteporidae
- Sonyea Group- Stenolaemata (Sulcoreteporidae)
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- Cuvillier, J., and H. Schurmann. "Recognition of Invertebrate Fossil Fragments in Rocks and Thin Sections." Google Books. N.p., 1969. Web. 19 Apr. 2016.
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- Http://www.dcnr.state.pa.us/cs/groups/public/documents/document/dcnr_20027631.pdf. The Bureau of Topographic and Geologic Survey. Web. 29 Feb. 2016.
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