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Almost all bryozoans are colony-forming animals. Many millions of individuals can form one colony. The colonies range from millimeters to meters in size, but the individuals that make up the colonies (the '''zooids''') are tiny, usually less than a millimeter long. In each colony, different individuals assume different functions. Some individuals gather up the food for the colony (autozooids), others depend on them (heterozooids). Some individuals are devoted to strengthening the colony ([[kenozooids]]), and still others to cleaning the colony ([[vibracula]]). There is only a single known solitary species, ''[[Monobryozoon ambulans]]'', which does not form colonies.
Almost all bryozoans are colony-forming animals. Many millions of individuals can form one colony. The colonies range from millimeters to meters in size, but the individuals that make up the colonies (the '''zooids''') are tiny, usually less than a millimeter long. In each colony, different individuals assume different functions. Some individuals gather up the food for the colony (autozooids), others depend on them (heterozooids). Some individuals are devoted to strengthening the colony ([[kenozooids]]), and still others to cleaning the colony ([[vibracula]]). There is only a single known solitary species, ''[[Monobryozoon ambulans]]'', which does not form colonies.

==Interaction with humans==
[[Bryozoa]]
Bryozoa generally do not interact with humans as something of a rule. This is due to a longstanding [[feud]]
with humans after an incident in 1922 when a [[colony]] of Bryozoa were involved in a scuffle with an
unknown man over a disagreement regarding [[coleslaw]]. Charles McRogersonstone - a member of the colony - was quoted after the incident as saying ''It was truly awful. I had no idea that soggy [[carrot]] could inflict such damage''.


==Evolutionary history==
==Evolutionary history==

Revision as of 15:28, 12 August 2009

Bryozoa
Temporal range: Ordovician - Recent
"Bryozoa", from Ernst Haeckel's Kunstformen der Natur, 1904
Scientific classification
Domain:
Eukarya
Kingdom:
Animalia
Superphylum:
Lophotrochozoa
Phylum:
Bryozoa
Classes

Stenolaemata
Gymnolaemata
Phylactolaemata

Synonyms

Ectoprocta

Bryozoans are tiny colonial animals that generally build stony skeletons of calcium carbonate, superficially similar to coral (although some species lack any calcification in the colony and instead have a mucilaginous structure). Members of the phylum Bryozoa are known as "moss animals" or "moss animacules" (which is the literal translation of the Greek term βρυόζωα, "bryózoa") or as "sea mats". They generally prefer warm, tropical waters, but are known to occur worldwide. There are about 8,000 living species, with several times that number of fossil forms known.

Distinguishing features

Bryozoans, phoronids and brachiopods strain food out of the water by means of a lophophore, a "crown" of hollow tentacles.[1] Entoprocts, another phylum of filter-feeders, look rather like bryozoans but their lophophore-like feeding structure has solid tentacles, their anus lies inside rather than outside the base of the "crown" and they have no coelom.[2] Phoronids are very similar to bryozoans but are much larger and, although they often grow in clumps, do not form colonies consisting of clones.[3] Brachiopods, closely related to bryozoans and phoronids, are distinguished by having shells rather like those of bivalves.[4]

Some encrusting bryozoan colonies with mineralized exoskeletons look very like small corals. However, bryozoan colonies are founded by an ancestrula, which is round rather than shaped like a normal zooid of that species. On the other hand the founding zooid of a coral has a normal shape.[5]

Summary of distinguishing features
  Bryozoa[1] Other lophophorates[6] Other Lophotrochozoa Similar-looking phyla
Phoronida[3] Brachiopoda[4] Annelida[7] Entoprocta[2] Corals (class in phylum Cnidaria)[5]
Coelom Three-part One per segment in basic form; merged in some taxa none
Formation of coelom Uncertain because metamorphosis of larvae into adults makes this impossible to trace Enterocoely Schizocoely not applicable
Lophophore With hollow tentacles none Similar-looking feeding structure, but with solid tentacles none
Feeding current From tips to bases of tentacles not applicable From bases to tips of tentacles not applicable
Position of anus Outside base of lophophore Varies, none in some species Rear end, but none in Siboglinidae Inside base of lophophore-like organ none
Colonial Colonies of clones in most; one solitary genus Sessile species often form clumps, but with no active co-operation Colonies of clones in some species; some solitary species Colonies of clones
Shape of founder zooid Round, unlike normal zooids[5] not applicable Same as other zooids
Mineralized exoskeletons Some taxa no Bivalve-like shells Some sessile taxa build mineralized tubes no Some taxa

Description

Types of zooid

All bryozoans are colonial except for one genus, Monobryozoon.[8][9] Individual members of a bryozoan colony are about 0.5 millimetres (0.020 in) long and are known as "zooids",[1] since they are not fully-independent animals.[10] All colonies contain feeding zooids, known as autozooids, and those of some groups also contain non-feeding specialist heterozooids;[9] colony members are genetically identical and co-operate, rather like the organs of larger animals.[1] What type of zooid grows where in a colony is determined by chemical signals from the colony as a whole or sometimes in response to the scent of predators or rival colonies.[9]

The bodies of all types have two main parts. The "cystid" consists of the body wall and whatever type of exoskeleton is secreted by the epidermis. The exoskeleton may be organic (chitin, polysaccharide or protein) or made of the mineral calcium carbonate. The body wall consists of the epidermis, basal lamina (a mat of non-cellular material), connective tissue, muscles, and the mesothelium which lines the coelom (main body cavity).[1] – except that in in one class the mesothelium is split into two separate layers, the inner one forming a membranous sac that floats freely and contains the coelom, and the outer one attached to the body wall and enclosing the membranous sac in a pseudocoelom.[11] The other main part of the bryozoan body, known as the "polypide" and situated almost entirely within the cystid, contains the nervous system, digestive system, some specialized muscles and the feeding apparatus or other specialized organs that take the place of the feeding apparatus.[1]

Feeding zooids

The most common type of zooid is the feeding autozooid, in which the polypide bears a "crown" of hollow tentacles called a lophophore, which captures food particles from the water.[9] In all colonies a large percentage of zooids are autozooids, and some consist entirely of autozooids, some of which also engage in reproduction.[12]

The "crown" may be a full circle or U-shaped.[1] The sides of the tentacles bear fine hairs called cilia, whose beating drives a water current from the tips of the tentacles and out between their bases. Food particles that collide with the tentacles are trapped by mucus ("slime"), and further cilia on the inner surfaces of the tentacles drive the particles towards the mouth, which lies in the center of the base of the "crown".[13]

The lophophore and mouth are mounted on a flexible tube called the "invert" because it can be turned inside-out and withdrawn into the polypide,[1] rather like the finger of a rubber glove; in this position the lophophore lies inside the invert and is folded like the spokes of an umbrella. The invert is withdrawn, sometimes within 60 milliseconds, by a pair of retractor muscles that are anchored at the far end of the cystid. Sensors at the tips of the tentacles may check for signs of danger before the invert and lophophore are fully extended. Extension is driven by an increase in internal fluid pressure, which species with flexible exoskeletons produce by contracting circular muscles that lie just inside the body wall,[1] while species with a membranous sac use circular muscles to squeeze this.[11] Some species with rigid exoskeletons have a flexible membrane that replaces part of the exoskeleton, and transverse muscles anchored on the far side of the exoskeleton increase the fluid pressure by pulling the membrane inwards.[1] In others there is no gap in the protective skeleton, and the transverse muscles pull on a flexible sac which is connected to the water outside by a small pore; the expansion of the sac increases the pressure inside the body and pushes the invert and lophophore out.[1] In some species the retracted invert and lophophore are protected by an operculum ("lid"), which is closed by muscles and opened by fluid pressure.[1]

The gut is U-shaped, running from the mouth, in the center of the lophophore, down into the animal's interior and then back to the anus, which is located on the invert, outside and usually below the lophophore.[1] A network of strands of mesothelium called "funiculi" ("little ropes"[14]) connects the mesothelium covering the gut with that lining the body wall. The wall of each strand is made of mesothelium, and surrounds a space filled with fluid, thought to be blood.[1] A colony's zooids are connected, enabling autozooids to share food with each other and with any non-feeding heterozooids.[1] The method of connection varies between the different classes of bryozoans, ranging from quite large gaps in the body walls to small pores through which nutrients are passed by funiculi.[1][11]

There is a nerve ring round the pharynx (throat) and a ganglion that serves as a brain to one side of this. Nerves run from the ring and ganglion to the tentacles and to the rest of the body.[1] Bryozoans have no specialized sense organs, but cilia on the tentacles act as sensors. Members of the genus Bugula grow towards the sun, and therefore must be able to detect light.[1] In colonies of some species, signals are transmitted between zooids through nerves that pass through pores in the body walls, and coordinate activities such as feeding and the retraction of lophophores.[1]

The solitary individuals of Monobryozoon are autozooids with pear-shaped bodies. The wider ends have up to 15 short, muscular projections by which the animals anchor themselves to sand or gravel[15] and pull themselves through the sediments.[16]

Avicularia

Some authorities use the term "avicularia" to refer to any type of zooid in which the lophophore is replace by an extension that serves some non-feeding function,[12] while others apply the term only to those with beak-like polypides that defend the colony against invaders and small predators, killing some and biting the appendages of others.[1] In some forms of defensive zooid the beak is mounted on a peduncle (stalk), and their bird-like appearance is responsible for the name "avicularia" (from the Latin avis, meaning "bird"[citation needed]) – Charles Darwin described these as like "the head and beak of a vulture in miniature, seated on a neck and capable of movement"[12] – stalked forms make "repeated nodding motions".[1]

The lower jaws of defensive avicularia are modified versions of the opercula that protect the retracted lophophores in autozooids of some species, and are snapped shut "like a mousetrap" by similar muscles.[1] They are opened by other muscles that attach to the lower jaw,[12] or by internal muscles that raise the fluid pressure by pulling on a flexible membrane.[1] The actions of defensive avicularia are controlled by tufts of short sensory cilia at the backs of their mouths.[1] Defensive avicularia appear in various positions: some take the place of autozooids, some fit into small spaces between autozooids and small avicularia may occur on the surfaces of other zooids.[12]

Vibracula

In these zooids, regarded by some as a type of avicularia,[12] the operculum is modified to form a long bristle that has a wide range of motion. In most species that have them, vibracula are generally regarded as cleaners because of their sweeping movements, and in some species that form mobile colonies the vibracula round the edges are used as legs for burrowing and walking.[1][12]

Other types of colonial zooid

Kenozooids (from Greek κενος meaning "empty"[17]) consist only of the body wall and funicular strands crossing the interior,[1] and no polypide.[9] In some species they form the stems of branching structures, while in others they act as spacers that enable colonies to grow quickly in a new direction.[9][12]

Spinozooids form defensive spines, and sometimes appear on top of autozooids. Gonozooids act as brood chambers for fertilized eggs.[9] Some species have miniature nanozooids with small single-tentacled polypides, and these may grow on other zooids or within the body walls of autozooids that have degenerated.[12]

Colony forms and composition

Although zooids are microscopic, colonies range in size from 1 centimeter (0.39 in) to over 1 meter (3.3 ft).[1] However, the majority are under 10 centimeters (3.9 in) across.[5] The shapes of colonies vary widely, depend on the pattern of budding by which they grow, the variety of zooids present and the type and amount of skeletal material they secrete.[1]

Some marine species are bush-like or fan-like, supported by "trunks" and "branches" formed by kenozooids, with feeding autozooids growing from these. Colonies of these types are generally unmineralized but may have exoskeletons made of chitin.[1] Others look like small corals, producing heavy lime skeletons.[18] The great majority of species form colonies which consist of sheets of autozooids. These sheets may form leaves, tufts or, in the genus Thalmoporella, structures that resemble an open head of lettuce.[1]

The most common form, however, is encrusting, in which a one-layer sheet of zooids spreads over a hard surface or over seaweed. Some encrusting colonies may grow to over 50 centimeters (1.6 ft) and contain about 2,000,000 zooids.[1] These species generally have exoskeletons reinforced with calcium carbonate, and the openings through which the lophohores protrude are on the top or outer surface.[1] The moss-like appearance of encrusting colonies gives the phylum its name (from βρυος bryos meaning "moss" and ζωον zoon meaning "animal").[19]) Large colonies of encrusting species often have "chimneys", gaps in the canopy of lophophores, through which they swiftly expel water that has been seived, and thus avoid re-filtering water that is already exhausted.[20] They are formed by patches of non-feeling heterozooids.[21] New chimneys appear near the edges of expanding colonies, at points where the speed of the outflow is already high, and do not change position if the water flow changes.[22]

Some freshwater species secrete a mass of gelatinous material, up to 1 meter (3.3 ft) in diameter, to which the zooids stick. Other freshwater species have plant-like shapes with "trunks" and "branches", which may stand erect or spread over the surface. A few species can creep at about 2 centimeters (0.79 in) per day.[1]

Each colony grows asexual budding from a single zooid known as the ancestrula,[1] which is round rather than shaped like a normal zooid.[5]. This occurs at the tips of "trunks" or "branches" in forms that have this structure. Encrusting colonies grow round their edges. In species with calcareous exoskeletons, these do not mineralize until the zooids are fully grown. Colony lifespans range from one to about 12 years, and the short-lived species pass though several generations in one season.[1]

Species that produce defensive zooids do so only when threats have already appeared, and may do so within 48 hours.[9] The theory of "induced defenses" suggests that production of defenses is expensive and that colonies which defend themselves too early or too heavily will have reduced growth rates and lifespans. This "last minute" approach to defense is feasible because the loss of zooids to a single attack is unlikely to be significant.[9] Colonies of some encrusting species also produce special heterozooids to limit the expansion of other encrusting organisms, especially other bryozoans. In some cases this reponse is more belligerent if the opposition is smaller, which suggests that zooids on the edge of a colony can somehow sense the size of the opopnent. Some species consistently prevail against certain others, but most turf wars are indecisive and the combatants soon turn to growing in uncontested areas.[9] Bryzoans competing for territory do not use the sophisticated techniques employed by sponges or corals, possibly because the shortness of bryozoan lifespans makes heavy investment in turf wars unprofitable.[9]

Feeding and excretion

Most species are filter feeders that seive small particles, mainly phytoplankton (microscopic floating plants), out of the water. While the currents they generate to draw food towards the mouth are well understood, the exact method of capture is still debated. All species also flick larger particles towards the mouth with a tentacle, and a few capture zooplankton (planktonic animals) by using their tentacles as cages. In addition the tentacles, whose surface area is increased by microvilli (small hairs and pleats), absorb organic compounds dissolved in the water.[1] Unwanted particles may be flicked away by tentacles or shut out by closing the mouth.[1] A study in 2008 showed that both encrusting and erect colonies fed more quickly and grew faster in gentle than in strong currents.[23]

In some species the first part of the stomach forms a muscular gizzard lined with chitinous teeth that crush armored prey such as diatoms. Wave-like peristaltic contractions move the food through the stomach for digestion. The final section of the stomach is lined with cilia (minute hairs) that compress undigested solids, which then pass through the intestine and out through the anus.[1]

There are no nephridia ("little kidneys") or other excretory organs in bryzoa,[9] and it is thought that ammonia diffuses out through the body wall and lophophore.[1] More complex waste products are not excreted but accumulate in the polypide, which degenerates after a few weeks. Some of the old polypide is recycled, but much of it remains as a large mass of dying cells containing accumulated wastes, and this is compressed into a "brown body". When the degeneration is complete, the cystid (outer part of the animal) produces a new polypide, and the brown body remains in the coelom, or is surrounded by the stomach of the new polypide and expelled next time the animal defecates.[1]

Respiration and circulation

There are no respiratory organs, heart or blood vessels. Instead zooids absorb oxygen and eliminate carbon dioxide through the body wall and especially the lophophore.[1] The fluid in the coelom transports gases and nutrients and its circulation is passive, except that some relatively large species use cilia to boost its speed.[1] The different bryozoan groups use various methods to share nutrients and oxygen between zooids: some have quite large gaps in the body walls, allowing the coelomic fluid to circulate freely; in others the funiculi (internal "little ropes"[14]) of adjacent zooids connect via small pores in the body wall.[1][11]

Reproduction and development

Zooids of all freshwater species are simultaneous hermaphrodites. Although those of many marine species are protandric, in other words function first as males and then as females, their colonies always contain a combination of zooids that are in their male and female stages. In all species the ovaries develop on the inside of the body wall, and the testes on the funiculus connecting the stomach to the body wall.[9] Eggs and sperm are released into the coelom, and sperm exit into the water through pores in the tips of some of the tentacles, and then are captured by the feeding currents of zooids that are producing eggs.[1] Some species' eggs are fertilized externally after being released through a pore between two tentacles, which in some cases is at the tip of a small projection called the "intertentacular organ" in the base of a pair of tentacles. Others' are fertilized internally, in the intertentacular organ or in the coelom.[1] In some species the mother provides a brood chamber for the fertilized eggs, and her polypide disintegrates, providing nourishment to the embryo. Others produce specialized zooids to serve as brood chambers, and their eggs divide within this to produce up to 100 identical embryos.[9]

The cleavage of bryozoan eggs is biradial, in other words the early stages are bilaterally symmetrical. It is unknown how the coleom forms, since the metamorphosis from larva to adult destroys all of the larva's internal tissues. The blastopore, an opening which in many animals tunnels through to form the gut, closes, and a new opening develops to create the mouth.[1]

Bryozoan larvae vary in form, but all have a band of cilia round the body which enables them to swim, and a tuft of cilia at the top.[1] A few species produce cyphonautes larvae which have little yolk but a well-developed mouth and gut, and live as plankton for a considerable time before settling. These larvae have triangular shells of chitin, with one corner at the top and the base open, forming a hood round the downward-facing mouth.[9] In 2006 it was reported that the cilial of cyphonautes larvae use the same range of techniques as those of adults to capture food.[24] Species that brood their embryos form larvae that are nourished by large yolks, have no gut and do not feed, and such larvae quickly settle on a surface.[1] In all marine species the larvae produce cocoons in which they metamorphose completely after settling: the larva's epidermis becomes the lining of the coelom, and the internal tissues are converted to a food reserve that nourishes the developing zooid until it is ready to feed.[1] The larvae of freshwater bryozoans produce multiple polypides, so that the new colony starts with several zooids.[1] In all species the founder zooids then grow the new colonies by budding clones of themselves. In freshwater species, zooids die after producing several clones, so that living zooids are found only round the edges of a colony.[1]

Freshwater bryozoans also reproduce asexually by a method that enables a colony's lineage to survive the variable and uncertain conditions of freshwater enviroments.[9] Throughout summer and autumn they produce disc-shaped statoblasts, masses of cells that function as "survival pods" rather like the gemmules of sponges.[1] Statoblasts form on the funiculus connected to the parent's gut, which nourishes them.[9] As they grow, statoblasts develop protective bivalve-like shells made of chitin. When they mature, some statoblasts stick to the parent colony, some fall to the bottom, some contain air spaces that enable them to float,[1] and some remain in the parent's cystid to re-build the colony if it dies.[9] Statoblasts can remain dormant for considerable periods, and while dormant can survive harsh conditions such as freezing and dessication. They can be transported across long distances by animals, floating vegetation, currents[1] and winds[9], and even in the guts of larger animals.[25] When conditions improve, the valves of the shell separate and the cells inside develop into a zooid that tries to form a new colony. A study estimated that one group of colonies in a patch measuring 1 square metre (11 sq ft)* produced 800,000 statoblasts.[1]

Classification and diversity

Under the Linnaean system of classification, which is still used as a convenient way to label groups of organisms,[26] living members of the phylum Bryozoa are divided into:[1][9]

Class Phylactolaemata Stenolaemata Gymnolaemata
Order Plumatellida[27] Cyclostomata Ctenostomata Cheilostomata
Environments Freshwater Marine Marine Mostly marine
Colony shapes Gelatinous masses or tubular branching strutures[28] Erect or encrusting   Encrusting
Exoskeleton material Gelatinous or membranous; unmineralized Mineralized Chitin, gelatinous or membranous; unmineralized Mineralized
Operculum ("lid") none none[29] None in most species Yes (except in genus Bugula)
Shape of lophophore U-shaped, two concentric bands of tentacles
(except in genus Fredericella)		 Circular, one ring of tentacles
How lophophore extended Compressing the whole body wall Compressing the membranous sac
(separate inner layer of epithelium that lines the coelom)		 Pulling inwards of a flexible section of body wall, or making an internal sac expand.
Types of zooid Autozooids only Limited heterozooids, mainly gonozooids[30] Stolons and spines as well as autozooids[30] Full range of types

Counts of formally described species range between 4,000 and 4,500.[31] The Gymnolaemata and especially Cheilostomata have the greatest numbers of species, possibly of their wide range of specialist zooids.[9]

Ecology

Habitats and distribution

Most marine species live in tropical waters less than 100 metres (330 ft)*. However, a few have been found deep-sea trenches,[32] especially around cold seeps, and others near the poles.[33][34] The great majority are sessile. Encrusting forms are much the commonest of these in shallow seas, but erect forms become more common as the depth increases.[33] A few marine species can move, and an Antarctic species forms floating colonies.[33]

The phylactolaemates live in all types of freshwater environment: lakes and ponds, rivers and streams, and estuaries. Some ctenostomes are exclusively freshwater while others prefer brackish water but can survive in freshwater.[28] Scientists' knowledge of bryozoan populations in many parts of the world is incomplete, even in some parts of Europe. It was long thought that some freshwater species occurred worldwide, but since 2002 all of these have been split into more localized species.[28]

Interactions with non-human organisms

The lace-like bryozoan species Membranipora membranacea, whose colonies feed and grow exceptionally fast in a wide range of current speeds, was first noticed in the Gulf of Maine in 1987 and quickly became the most abundant organism living on kelps.[23] This invasion reduced the kelp population by breaking their fronds,[1] so that its place as the dominant "vegetation" in some areas was taken by another invader, the large alga Codium fragile tomentosoides.[23] These changes reduced the area of habitat available for local fish and invertebrates. M. membranacea has also invaded the northwest coast of the U.S.A.[1] A few freshwater species have been also found thousands of kilometers from their native ranges. Some may have been transported naturallly as statoblasts. Others more probably were spread by humans, for example on imported water plants or a stowaways on ships.[25]


Most species of bryozoa live in marine environments, though there are about 50 species which inhabit freshwater. In their aquatic habitats, bryozoans may be found on all types of hard substrates: sand grains, rocks, shells, wood, blades of kelp, pipes and ships may be heavily encrusted with bryozoans. Some bryozoan colonies, however, do not grow on solid substrates, but form colonies on sediment. While some species have been found at depths of 8,200 m (26,900 ft), most bryozoans inhabit much shallower water. Most bryozoans are sessile, but a few colonies are able to creep about, and some non-colonial bryozoans live and move about in the spaces between sand grains. One remarkable species makes its living while floating in the Southern Ocean. Fossil bryozoans are common throughout the world in sedimentary rocks representing shallow marine habitats, especially in rocks of post-Cambrian Paleozoic age.

Almost all bryozoans are colony-forming animals. Many millions of individuals can form one colony. The colonies range from millimeters to meters in size, but the individuals that make up the colonies (the zooids) are tiny, usually less than a millimeter long. In each colony, different individuals assume different functions. Some individuals gather up the food for the colony (autozooids), others depend on them (heterozooids). Some individuals are devoted to strengthening the colony (kenozooids), and still others to cleaning the colony (vibracula). There is only a single known solitary species, Monobryozoon ambulans, which does not form colonies.

Evolutionary history

Fossil record

Bryozoan fossils in an Upper Ordovician oil shale (kukersite), northern Estonia.

Fossils of about 15,000 bryozoan species have been found. Marine taxa with mineralized skeletons appear in rocks dating from early in the Ordovician period, which began about 488 million years ago.[5] By the Middle Ordovician, about 465 million years ago, fossils of all the modern orders of stenolaemates and of the ctenostome order of gymnolaemates had appeared. Around the same time, other types of filter feeders appeared, which suggests that some change made the environment more favorable for this lifestyle.[5] Fossils of cheilostomates, another order of gymnolaemates, first appear in the Mid Jurassic, about 172 million years ago, and from the Cretaceous to the present these have been the most abundant and diverse bryozoans.[5] Marine fossils from the Paleozoic era, which ended 251 million years ago, 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.[35] Fossils of the soft, freshwater phylactolaemates are very rare,[5] appear in and after the Late Permian (which began about 260 million years ago) and consist entirely of their durable statoblasts.[28] There are no known fossils of freshwater members of other classes.[28]

Evolutionary family tree

See also

References

An Upper Ordovician cobble with the edrioasteroid Cystaster stellatus and the thin branching cyclostome bryozoan Corynotrypa. Kope Formation, northern Kentucky.
  • Hall, S.R., Taylor, P.D., Davis, S.A. and Mann, S., 2002. Electron diffraction studies of the calcareous skeletons of bryozoans. Journal of Inorganic Biochemistry 88: 410-419. [1]
  • Hayward, P.G., J.S. Ryland and P.D. Taylor (eds.), 1992. Biology and Palaeobiology of Bryozoans, Olsen and Olsen, Fredensborg, Denmark.
  • Robinson, R.A. (ed.), 1983. Treatise on Invertebrate Paleontology, Part G, Bryozoa (revised). Geological Society of America and University of Kansas Press.
  • Sharp, J.H., Winson, M.K. and Porter, J.S. 2007. Bryozoan metabolites: an ecological perspective. Natural Product Reports 24: 659-673.
  • Taylor, P.D. and Wilson, M.A., 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62: 1-103. [2]
  • Woollacott, R.M. and R.L. Zimmer (eds), 1977. The Biology of Bryozoans, Academic Press, New York.
  1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004). "Lophoporata". Invertebrate Zoology (7 ed.). Brooks / Cole. pp. 829–845. ISBN 0030259827.{{cite book}}: CS1 maint: multiple names: authors list (link)
  2. ^ a b Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004), "Kamptozoa and Cycliophora", Invertebrate Zoology (7 ed.), Brooks / Cole, pp. 808–812, ISBN 0030259827{{citation}}: CS1 maint: multiple names: authors list (link)
  3. ^ a b Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004). "Lophoporata". Invertebrate Zoology (7 ed.). Brooks / Cole. pp. 817–821. ISBN 0030259827.{{cite book}}: CS1 maint: multiple names: authors list (link)
  4. ^ a b Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004). "Lophoporata". Invertebrate Zoology (7 ed.). Brooks / Cole. pp. 821–829. ISBN 0030259827.{{cite book}}: CS1 maint: multiple names: authors list (link)
  5. ^ a b c d e f g h i Rich, T.H. (1997). ""Moss Animals", or Bryozoans". The fossil book. Dover Publications. pp. 142–152. ISBN 9780486293714. Retrieved 2009-08-07. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004). "Lophoporata". Invertebrate Zoology (7 ed.). Brooks / Cole. p. 817. ISBN 0030259827.{{cite book}}: CS1 maint: multiple names: authors list (link)
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  13. ^ Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004). "Lophoporata". Invertebrate Zoology (7 ed.). Brooks / Cole. p. 817. ISBN 0030259827.{{cite book}}: CS1 maint: multiple names: authors list (link)
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  16. ^ Giere, O. (2009). "Tentaculata". Meiobenthology (2 ed.). Springer-Verlag. p. 227. ISBN 9783540686576. Retrieved 2009-08-2. {{cite book}}: Check date values in: |accessdate= (help)
  17. ^ Liddell, H.G. (1940). "kenos". A Greek-English Lexicon. R. Clarendon Press. ISBN 0198642261. Retrieved 2009-08-01. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  18. ^ Branch, M.L. (2007). "Bryozoa: Moss or Lace Animals". Two Oceans - A Guide to the Marine Life of Southern Africa. Struik. pp. 104–110. ISBN 9781770076334. Retrieved 2009-08-02. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
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  24. ^ Strathmann, R.R. (March 2006). "Versatile ciliary behaviour in capture of particles by the bryozoan cyphonautes larva". Acta Zoologica. 87 (1). The Royal Swedish Academy of Sciences: 83–89. doi:10.1111/j.1463-6395.2006.00224.x.
  25. ^ a b Wood, T.S. (1999). "Asajirella gelatinosa in Panama: a bryozoan range extension in the Western Hemisphere". Hydrobiologia. 390 (1–3). Kluwer Academic: 19–23. doi:10.1023/A:1003502814572. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
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  35. ^ Wood, R. (1999). Reef evolution. Oxford University Press. pp. 235–237. ISBN 0-19-857784. Retrieved 2009-08-11. {{cite book}}: Check |isbn= value: length (help)
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