Editing Bryozoa (section)

=== Interaction with humans ===
[[Fish farms]] and hatcheries have lost stock to [[proliferative kidney disease]], which is caused by one or more [[myxozoan]]s that use bryozoans as alternate hosts.<ref name="AndersonCanningOkamura2004BryozoanHostsForPKX" />

Some fishermen in the [[North Sea]] have had to find other work because of a form of [[eczema]] (a skin disease) known as "[[Dogger Bank itch]]",<ref name="Jones2006AppliedPaleo" /> caused by contact with bryozoans that have stuck to nets and lobster pots.<ref>{{cite journal|last=Clin|first=B.|title=Professional photosensitive eczema of fishermen by contact with bryozoans: disabling occupational dermatosis|journal=International Maritime Health|volume=59|issue=1–4|pages=1–4|url=http://www.imh.mug.edu.pl/attachment/attachment/4761/2008t4.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.imh.mug.edu.pl/attachment/attachment/4761/2008t4.pdf |archive-date=2022-10-09 |url-status=live|access-date=2009-08-18|pmid=19227737|year=2008}}</ref>

Marine bryozoans are often responsible for [[biofouling]] on ships' hulls, on docks and marinas, and on offshore structures. They are among the first colonizers of new or recently cleaned structures.<ref name="MargulisSchwartz1998FiveKingdomsBryozoa">{{cite book|last=Margulis|first=L.|author-link=Lynn Margulis|author2=Schwartz K.V.|title=Five kingdoms: an illustrated guide to the phyla of life on earth|publisher=Elsevier|year=1998|page=[https://archive.org/details/fivekingdomsillu00marg_0/page/335 335]|chapter=Bryozoa|isbn=978-0-7167-3027-9|chapter-url=https://books.google.com/books?id=9IWaqAOGyt4C&q=bryozoa+ectoprocta+fouling|access-date=2009-08-20|url=https://archive.org/details/fivekingdomsillu00marg_0/page/335}}</ref> Freshwater species are occasional nuisances in water pipes, drinking water purification equipment, sewage treatment facilities, and the cooling pipes of power stations.<ref name="MassardGeimer2008FreshwaterBryoDiversity" /><ref>{{cite journal|last1=Wood|first1=T.S.|date=February 1999|title=Biofouling of wastewater treatment plants by the freshwater bryozoan, ''Plumatella vaihiriae''|journal=Water Research|volume=33|issue=3|pages=609–614|doi=10.1016/S0043-1354(98)00274-7|last2=Marsh|first2=Terrence G}}</ref>

A group of chemicals called [[bryostatin]]s can be extracted from the marine bryozoan ''[[Bugula neritina]]''. In 2001 pharmaceutical company [[GPC Biotech]] licensed bryostatin 1 from [[Arizona State University]] for commercial development as a treatment for cancer. GPC Biotech canceled development in 2003, saying that bryostatin 1 showed little effectiveness and some toxic side effects.<ref>{{cite web|url=http://www.marinebiotech.org/bryostatin.html|archive-url=https://web.archive.org/web/20070509175548/http://www.marinebiotech.org/bryostatin.html|url-status=dead|archive-date=9 May 2007|title=Bryostatin 1|date=19 June 2006|access-date=2009-08-20}}</ref> In January 2008 a [[clinical trial]] was submitted to the United States [[National Institutes of Health]] to measure the safety and effectiveness of Bryostatin 1 in the treatment of [[Alzheimer's disease]]. However, no participants had been recruited by the end of December 2008, when the study was scheduled for completion.<ref>{{cite web|url=http://clinicaltrials.gov/ct2/show/results/NCT00606164|title=Safety, Efficacy, Pharmacokinetics, and Pharmacodynamics Study of bryostatin 1 in Patients With Alzheimer's Disease|date=19 August 2009|publisher=National Institutes of Health|access-date=2009-08-20|archive-date=13 June 2011|archive-url=https://web.archive.org/web/20110613200451/http://clinicaltrials.gov/ct2/show/results/NCT00606164|url-status=live}}</ref> More recent work shows it has positive effects on cognition in patients with Alzheimer's disease with few side effects.<ref>{{cite journal | pmc=5438479 | year=2017 | last1=Nelson | first1=T. J. | last2=Sun | first2=M. K. | last3=Lim | first3=C. | last4=Sen | first4=A. | last5=Khan | first5=T. | last6=Chirila | first6=F. V. | last7=Alkon | first7=D. L. | title=Bryostatin Effects on Cognitive Function and PKCɛ in Alzheimer's Disease Phase IIA and Expanded Access Trials | journal=Journal of Alzheimer's Disease | volume=58 | issue=2 | pages=521–535 | doi=10.3233/JAD-170161 |doi-access=free | pmid=28482641 }}</ref> About {{convert|1000|kg|lb}} of bryozoans must be processed to extract {{convert|1|g|oz|frac=32}} of bryostatin, As a result, synthetic equivalents have been developed that are simpler to produce and apparently at least as effective.<ref>{{cite journal|last1=Wender|first1=P.A.|date=20 November 2002|title=The Practical Synthesis of a Novel and Highly Potent Analogue of Bryostatin|journal=Journal of the American Chemical Society|volume=124|issue=46|pages=13648–13649|doi=10.1021/ja027509+|pmid=12431074|last2=Baryza|first2=JL|last3=Bennett|first3=CE|last4=Bi|first4=FC|last5=Brenner|first5=SE
|last6=Clarke|first6=MO|last7=Horan|first7=JC|last8=Kan|first8=C|last9=Lacôte|first9=E|bibcode=2002JAChS.12413648W | display-authors = 8}}</ref>
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== Anatomy ==
[[File:Costazia costazi.jpg|thumb|''[[Costazia costazi]]'', a [[coralline]] bryozoan]]
Bryozoan skeletons grow in a variety of shapes and patterns: mound-shaped, lacy fans, branching twigs, and even corkscrew-shaped. Their [[skeleton]]s have numerous tiny openings, each of which is the home of a minute animal called a '''zooid'''. They also have a [[body cavity|coelomate]] body with a looped alimentary canal or gut, opening at the mouth and terminating at the [[anus]]. They feed with a specialized, [[cilia]]ted structure called a [[lophophore]], which is a crown of [[tentacle]]s surrounding the mouth. Their diet consists of small microorganisms, including [[diatom]]s and other unicellular [[algae]]. In turn, bryozoans are preyed on by grazing organisms such as [[sea urchin]]s and fish. Bryozoans do not have any defined respiratory, or circulatory systems due to their small size. However, they do have a simple nervous system and a hydrostatic skeletal system. Several studies have been undertaken on the crystallography of bryozoan skeletons, revealing a complex fabric suite of oriented [[calcite]] or [[aragonite]] crystallites within an organic matrix – see for example Hall ''et al.'' (2002).

[[File:Lophophores bryozoan.jpg|thumb|right240px|bryozoan lophophores]]
The tentacles of the bryozoans are ciliated, and the beating of the [[cilia]] creates a powerful current of water which drives water together with entrained food particles (mainly phytoplankton) towards the mouth. The gut is U-shaped, and consists of a [[pharynx]] which passes into the [[esophagus]], followed by the [[stomach]], which has three parts: the [[cardia]], the [[caecum]], and the [[pylorus]]. The pylorus leads to an intestine and a short [[rectum]] terminating at the anus, which opens outside the [[lophophore]]. In some groups, notably some ctenostomes, a specialized [[gizzard]] may be formed from the proximal part of the cardia. Gut and lophophore are the principal components of the [[polypide]]. Cyclical degeneration and regeneration of the polypide is characteristic of marine bryozoans. After the final polypide degeneration, the skeletal aperture of the feeding zooid may become sealed by the secretion of a terminal [[Septum (marine biology)|diaphragm]]. In many bryozoans only the zooids within a few generations of the growing edge are in an actively feeding state; older, more proximal zooids (e.g. in the interiors of bushy colonies) are usually dormant.

[[File:Freshwater Bryozoan234.JPG|thumb|left|Freshwater bryozoan]]
Because of their small size, bryozoans have no need of a blood system. Gaseous exchange occurs across the entire surface of the body, but particularly through the tentacles of the lophophore.

Bryozoans can reproduce both sexually and asexually. All bryozoans, as far as is known, are [[hermaphroditic]] (meaning they are both male and female). [[Asexual reproduction]] occurs by budding off new zooids as the colony grows, and is the main way by which a colony expands in size. If a piece of a bryozoan colony breaks off, the piece can continue to grow and will form a new colony. A colony formed this way is composed entirely of [[Cloning|clones]] (genetically identical individuals) of the first animal, which is called the '''ancestrula'''.

One species of bryozoan, ''Bugula neritina'', is of current interest as a source of [[cytotoxicity|cytotoxic]] chemicals, [[bryostatin]]s, under clinical investigation as anti-cancer agents.

== Fossils ==
[[File:07PaleoFTb15.JPG|thumb|Twig-like bryozoan fossils, Upper [[Ordovician]], near Brookville, Indiana.]]
[[File:Prasopora.JPG|thumb|''Prasopora'', a trepostome bryozoan from the [[Ordovician]] of Iowa.]]
[[File:BrownBodies.jpg|thumb|A section through ''Prasopora'' showing "brown bodies" in many of the zooecia; [[Ordovician]] of Iowa.]]
[[File:OilShaleFossilsEstonia.jpg|thumb|Bryozoans in an Ordovician [[oil shale]], northern [[Estonia]].]]
[[File:Bryozoa Hallopora1.jpg|thumb|Detail of [[Hallopora]] fossil specimen on display at [[National Museum of Natural History|Smithsonian]], Washington, DC]]
[[Fossil]] bryozoans are found in rocks beginning in the [[Early Ordovician]] as part of the [[Ordovician radiation]]. They were often major components of Ordovician seabed communities and, like modern-day bryozoans, played an important role in [[sediment]] stabilization and binding, as well as providing sources of food for other [[benthic]] organisms. During the [[Mississippian]] (354 to 323 million years ago) bryozoans were so common that their broken skeletons form entire [[limestone]] beds. Bryozoan fossil record comprises more than 1,000 described species. It is plausible that the Bryozoa existed in the [[Cambrian]] but were soft-bodied or not preserved for some other reason; perhaps they evolved from a [[phoronid]]-like ancestor at about this time.

Bryozoans are important members of sclerobiont (organisms which dwell on hard substrates such as shells and rocks) communities in the fossil record and in the Recent. For a review of sclerobiont evolution, history and ecology, see Taylor & Wilson (2003).

Most fossil bryozoans have mineralized skeletons. The skeletons of individual zooids vary from tubular to box-shaped and contain a terminal aperture from which the [[lophophore]] is protruded to feed. No pores are present in the great majority of Ordovician bryozoans, but skeletal evidence shows that [[epithelia]] were continuous from one zooid to the next.

With regard to the bryozoan groups lacking mineralized skeletons, the [[statoblasts]] of freshwater [[phylactolaemates]] have been recorded as far back as the [[Permian]], and the [[ctenostome]] fossils date from the [[Triassic]].

One of the most important events during bryozoan evolution was the acquisition of a calcareous skeleton and the related change in the mechanism of tentacle protrusion. The rigidity of the outer body walls allowed a greater degree of zooid contiguity and the evolution of massive, multiserial colony forms.

== Classification ==
The bryozoans were formerly considered to contain two subgroups: the ''ectoprocta'' and the ''[[entoprocta]]'', based on the similar bodyplans and mode of life of these two groups. (Some researchers also included the [[Cycliophora]], which are thought to be closely related to the entoprocta.) However, the ectoprocta are ''coelomate'' (possessing a [[body cavity]]) and their embryos undergo [[radial cleavage]], while the entoprocta are ''acoelemate'' and undergo [[spiral cleavage]]. Molecular studies are ambiguous about the exact position of the entoprocta, but do not support a close relationship with the ectoprocta. For these reasons, the entoprocta are now considered a phylum of their own.<ref>{{cite book|author = James W. Valentine|title = On the origins of phyla |year = 2004|publisher = University of Chicago Press}}</ref> The removal of the 150 species of entoprocta leaves ''bryozoa'' synonymous with ''ectoprocta''; some authors have adopted the latter name for the group, but the majority continue to use the former.

The closest relations of the bryozoans appear to be the [[brachiopod]]s. The sister group to this clade is still unclear but this seems most likely to be the [[phoronid]]s.
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