) of eastern
Indiana, United States , United States The phylum was originally called "Polyzoa", but this name was eventually replaced by Ehrenberg's term "Bryozoa". in which the
anus lies outside the "crown" of tentacles. After the discovery of the
Entoprocta (), in which the anus lies within a "crown" of tentacles, the name "Bryozoa" was promoted to
phylum level to include the two
classes Ectoprocta and Entoprocta. However, in 1869 Hinrich Nitsche regarded the two groups as quite distinct for a variety of reasons, and coined the name "Ectoprocta" for Ehrenberg's "Bryozoa". Nevertheless, some notable scientists have continued to regard the "Ectoprocta" and Entoprocta as close relatives and group them under "Bryozoa". However, the change would have made it harder to find older works in which the phylum was called "Bryozoa", and the desire to avoid ambiguity, if applied consistently to all classifications, would have necessitated renaming of several other phyla and many lower-level groups. In practice, zoological naming of split or merged groups of animals is complex and not completely consistent. Works since 2000 have used various names to resolve the ambiguity, including: "Bryozoa", Some have used more than one approach in the same work. The common name "moss animals" is the literal meaning of "Bryozoa", from Greek ('moss') and ('animals'), based on the mossy appearance of encrusting species. Until 2008 there were "inadequately known and misunderstood type species belonging to the Cyclostome Bryozoan family Oncousoeciidae." Modern research and experiments have been done using low-vacuum scanning electron microscopy of uncoated type material to critically examine and perhaps revise the taxonomy of three genera belonging to this family, including
Oncousoecia,
Microeciella, and
Eurystrotos. This method permits data to be obtained that would be difficult to recognize with an optical microscope. The valid type species of
Oncousoecia was found to be
Oncousoecia lobulata. This interpretation stabilizes
Oncousoecia by establishing a type species that corresponds to the general usage of the genus. Fellow Oncousoeciid
Eurystrotos is now believed to be not conspecific with
O. lobulata, as previously suggested, but shows enough similarities to be considered a junior synonym of
Oncousoecia.
Microeciella suborbicularus has also been recently distinguished from
O. lobulata and
O. dilatans, using this modern method of low vacuum scanning, with which it has been inaccurately synonymized with in the past. A new genus has also been recently discovered called
Junerossia in the family Stomachetosellidae, along with 10 relatively new species of bryozoa such as
Alderina flaventa,
Corbulella extenuata,
Puellina septemcryptica,
Junerossia copiosa,
Calyptotheca kapaaensis,
Bryopesanser serratus,
Cribellopora souleorum,
Metacleidochasma verrucosa,
Disporella compta, and
Favosipora adunca.
Classification and diversity Counts of formally described species range between 4,000 and 4,500. The Gymnolaemata and especially Cheilostomata have the greatest numbers of species, possibly because of their wide range of specialist zooids. living members of the
phylum Bryozoa are divided into: Bryozoans with calcitic skeletons were a major source of the carbonate minerals that make up limestones, and their fossils are incredibly common in marine sediments worldwide from the Ordovician onward. However, unlike corals and other colonial animals found in the fossil record, Bryozoan colonies did not reach large sizes. Fossil bryozoan colonies are typically found highly fragmented and scattered; the preservation of complete zoaria is uncommon in the fossil record, and relatively little study has been devoted to reassembling fragmented zoaria. The largest known fossil colonies are branching trepostome bryozoans from Ordovician rocks in the United States, reaching 66 centimeters in height. about , all the modern
orders of
stenolaemates were present, Other types of
filter feeders appeared around the same time, which suggests that some change made the environment more favorable for this lifestyle. Marine fossils from the
Paleozoic era, which ended , are mainly of erect forms, those from the
Mesozoic are fairly equally divided by erect and encrusting forms, and more recent ones are predominantly encrusting. Fossils of the soft, freshwater
phylactolaemates are very rare,
Traditional view The traditional view is that the Bryozoa are a monophyletic group, in which the class
Phylactolaemata is most closely related to
Stenolaemata and
Ctenostomatida, the
classes that appear earliest in the fossil record. In 2009 another
molecular phylogeny study, using a combination of genes from
mitochondria and the
cell nucleus, concluded that Bryozoa is a
monophyletic phylum, in other words includes all the descendants of a common ancestor that is itself a bryozoan. The analysis also concluded that the
classes Phylactolaemata,
Stenolaemata and
Gymnolaemata are also monophyletic, but could not determine whether
Stenolaemata are more closely related to
Phylactolaemata or
Gymnolaemata. The Gymnolaemata are traditionally divided into the soft-bodied
Ctenostomatida and
mineralized Cheilostomata, but the 2009 analysis considered it more likely that neither of these
orders is monophyletic and that mineralized
skeletons probably evolved more than once within the early Gymnolaemata. Bryozoans' relationships with other phyla are uncertain and controversial. Traditional phylogeny, based on
anatomy and on the development of the adult forms from
embryos, has produced no enduring consensus about the position of ectoprocts. In the opinion of Ruth Dewel, Judith Winston, and Frank McKinney, "Our standard interpretation of bryozoan
morphology and
embryology is a construct resulting from over 100 years of attempts to synthesize a single framework for all invertebrates," and takes little account of some peculiar features of ectoprocts.
Entoprocts When entoprocts were discovered in the 19th century, they and bryozoans (ectoprocts) were regarded as classes within the phylum Bryozoa, because both groups were
sessile animals that
filter-fed by means of a crown of tentacles that bore
cilia. From 1869 onwards increasing awareness of differences, including the position of the entoproct
anus inside the feeding structure and the difference in the early
pattern of division of cells in their
embryos, caused scientists to regard the two groups as separate phyla,
Brachiopods were also assigned to the "Tentaculata", which were renamed
Lophophorata as they all use a
lophophore for filter feeding. The Lophophorata are usually defined as animals with a lophophore, a three-part coelom and a U-shaped gut. Bryozoan's tentacles bear cells with multiple
cilia, while the corresponding cells of phoronids', brachiopods' and pterobranchs' lophophores have one cilium per cell; and bryozoan tentacles have no hemal canal ("blood vessel"), which those of the other three phyla have. "Total evidence" analyses, which used both morphological features and a relatively small set of genes, came to various conclusions, mostly favoring a close relationship between lophophorates and Lophotrochozoa. A study of the mitochondrial DNA sequence suggests that the Bryozoa may be related to the
Chaetognatha. == Physiology ==