Lophophorata

	Mineralogy	Geologic Range	Habitat	Ecology	Other
stenolaemate bryozoans*	calcite (rarely aragonite)	Ordovician-Recent	marine	sessile, benthonic, colonial filter-feeder	long, tubular zooids
gymnolaemate bryozoans*	calcite, aragonite, or calcite and aragonite	Ordovician - Recent	marine	sessile, benthonic, colonial filter-feeder	short, box shaped zooids
acrotretid brachiopods*	chitinophosphatic, some calcite, rarely aragonite	Cambrian - Recent	marine	sessile, benthonic filter-feeder	small, circular, frequently attached
lingulid brachiopods*	chitinophosphatic	Cambrian - Recent	marine	burrowing, benthonic filter-feeder	finger-nail shaped, burrower
orthid brachiopods	calcite	Cambrian-Permian	marine	sessile, benthonic filter-feeder	no lophophore support, usually strophic, non-alate, fibrous, may be punctate or impunctate
strophomenid brachiopods	calcite	Ordovician - Jurassic	marine	sessile, benthonic filter-feeder	variable, strophic, laminar shell layer and pseudopunctae usual, some impunctate fibrous taxa
rhynchonellid brachiopods*	calcite	Ordovician - Recent	marine	sessile, benthonic filter-feeder	biconvex, with fold in brachial valve and sulcus in pedicle valve, astrophic, fibrous, impuctate, spiral lophophore support, usually with a small number of heavy ribs
spiriferid brachiopods	calcite	Ordovician - Jurassic	marine	sessile, benthonic filter-feeder	highly variable, spiral lophophore support, strophic and astrophic taxa, fibrous, punctate or impunctate
pentamerid brachiopods	calcite	Cambrian-Devonian	marine	sessile, benthonic filter-feeder	biconvex with spondylium structure in pedicle valve, strophic or astrophic, fibrous and impunctate
terbratulid brachiopods*	calcite	Ordovician - Recent	marine	sessile, benthonic filter-feeder	biconvex, with circular pedicle foramen in pedicle valve, usually astrophic, simple loop support for lophophore, punctate and fibrous

* Extant taxa

Phylum Bryozoa
..........Class Stenolaemata(Ordovician-Recent, 750 genera)
...............Order Cyclostomata (Ordovician-Recent)
...............Order Cystoporata (Ordovician-Triassic, 100 genera)
...............Order Trepostomata (Ordovician-Triassic, 200 genera)
...............Order Cryptostomata (Ordovician-Permian, 90 genera)
...............Order Fenestrata (Ordovician-Triassic, 100 genera)
..........Class Gymnolaemata(Ordovician-Recent, 1050 genera)
...............Order Ctenostomata (Ordovician-Recent, 50 genera)
...............Order Cheilostomata (Jurassic-Recent, 1000 genera)

Phylum Brachiopoda (Cambrian-Recent)
..........Class Inarticulata (Cambrian-Recent, approx. 220 genera)
...............Order Lingulida (Cambrian-Recent, 85 genera)
...............Order Acrotrerida(Cambrian-Recent, 120 genera)
(also)
...............Order Discinida (Ordovician-Recent)
...............Order Siphonotretida (Cambrian-Ordovician)
...............Order Paterinda (Cambrian- Ordovician, 14 genera)
...............Order Craniida (Cambrian-Recent)
...............Order Craniopsida (Ordovician-Carboniferous)
...............Order Trimerellida (Ordovician- Silurian)
...............Order Obolellida (Cambrian- Cambrian, 10 genera)
...............Order Kutorginida (Cambrian- Cambrian)
..........Class Articulata (Cambrian-Recent, appox. 3200 genera)
...............Order Orthida (Cambrian- Permian, 340 genera)
...............Order Strophomenida (Ordovician-Triassic, 865 genera)
...............Order Pentamerida (Cambrian-Devonian., 160 genera)
...............Order Rhynchonellida (Ordovician-Recent, 520 genera)
...............Order Spiriferida (Ordovician-Jurassic, 720 genera)
...............Order Terebratulida (Devonian-Recent, 540 genera)
...............Order Thecideidina (Triassic-Recent, 28 genera)

Superphylum Lophophorata
Phylum Bryozoa

(Ordovician-Recent)

Bryozoans (the name means "plant-animals") are exclusively colonial lophophorates. All bryozoan species have very well integrated colonial structures composed of ordered arrangements of tiny individuals (called zooids). Many bryozoans encrust on hard surfaces, while others are free-lying, or in one very strange case mobile. Overall colonial morphologies include small cap-shaped colonies, branching colonies, colonies with regularly shaped bumps and protrusions, sheet-like colonies, and massive colonies. Colonies start from a single individual zooid (called the ancestrula), and grow through asexual budding. The individual zooid is surrounded by a small skeletal box with a hinged top called an operculum. Some bryozoans have calcareous skeletons (and thus a good fossil record), while others have organic skeletons (and thus a very poor fossil record). The basic body usually consists of the lophophore, a set of muscles for protruding and retracting the lophophore, a digestive system, and a set of funicular strands (in gymnolaemates) or pores (in stenolaemates) through which the individual zooid can communicate with the rest of the colony. Specialization of individuals within a colony, or polymorphism, is common in some bryozoans groups. The most common zooid morphology in most bryozoans are feeding zooids, which are called autozooids. Other types of zooids include kenozoids (polymorphs lacking internal organs, used as skeletal space fillers), maternal zooids (polymorphs with specialized brooding pouches), and avicularia (polymorphs with processes on the opercula which serve cleaning and other purposes). There are two major classes of bryozoans with fossil records, the Stenolaemata (Ordovician to Recent) and Gymnolaemata (Ordovician to Recent).

Ranges of major bryozoan groups

Related Websites

• Philip Bock's Bryozoan Page
• Bryozoans (UCMP)
• Ectoprocta (Tree of Life)

Class Stenolaemata

(Ordovician-Recent)

This class of bryozoan was dominant during the Paleozoic. Members of the group have long, conical zooids. Many different types of stenolaemates are superficially similar, and can only be distinguished by thin-section analysis. Most stenolaemates have laminated calcite skeletons. Stenolaemates display many different colonial forms, including encrusters, branching colonies, massive colonies, and bifloiate colonies. Many colonies have zones of different sized zooids, or extrazooidal skeletal matter which gives the colony a spotty appearance. These areas, called maculae, appear to help direct excurrent water away from the colony, thus preventing some zooids from fouling other zooids, and increasing the efficiency of water flow across the colony as a whole. There are five orders of stenolaemates: Treptosoma (Ordovician to Triassic); Cystoporata (Ordovician to Triassic); Cryptosoma (Ordovician to Permian); Fenestrata (Ordovician to Triassic); and Tubuliporata (Ordovician to Holocene).

Class Gymnolaemata

(Ordovician-Recent)

Gymnolaemates are the dominant bryozoan group in Mesozoic and Cenozoic marine communities. Instead of having long tube-like zooids, like the stenolaemates, gymnolaemates have box-shaped zooids. Polymorphism is very common in this group.

Superphylum Lophophorata Phylum Brachiopoda (Cambrian-Recent) The brachiopod phylum diversified early in the Phanerozoic, and reached its acme in the Paleozoic. While some 300 species representing four orders, (Lingulida, Acrotretida, Rhychonellida, and Terebratulida) still inhabit the modern ocean, most of the brachiopod orders are extinct. While all brachiopods live in marine environments, some can tolerate swings in salinity, or even subarial exposure, and thus can live in the upper intertidal zone along rocky shores. Like their relatives the bryozoans, brachiopods respire and feed using a lophophore, and like bryozoans, they are masters of manipulating water flow. Unlike bryozoans, brachiopods are solitary. All brachiopods secrete a mineralized shell composed of two bilaterally symmetrical valves. The valves are manipulated by paired sets of muscles which insert into the interior of the valves, leaving scars. The valve to which the lophophore is attached is called the brachial valve, and is defined as being dorsally oriented. The other valve is called the pedicle valve and is defined as being ventrally oriented. A fleshy stalk, called a pedicle, usually protrudes out between the valves in the posterior of the shell, allowing the brachiopod to attach to the substrate (in most cases) or aids in burrowing (in the case of lingulids). While brachiopods superficially resemble molluscan bivalves, the two groups are easily distinguished from each other by careful observation. Related Websites Smithsonian Institute brachiopod database EuroBrachNet Brachiophile Brachiopods (UCMP) Brachiopods (Tree of Life)

Class Inarticulata

(Cambrian-Recent)

Inarticulate brachiopods were important members of the Cambrian fauna, and reached a diversity maximum during the Ordovician, but their fossils are also regularly found in younger rocks. Most inarticulates secreted a chitinophosphatic (calcium phosphate embedded in an organic matrix) skeleton, although several groups (including one living group) secreted a calcium carbonate skeleton. The valves of inarticulates are not joined into a hinge structure, like their articulate cousins. The valves are almost always simple, without complex ribbing, spines, or other ornamentation. They are characteristically non-descript. However, they have some morphological features which are more "advanced" than articulates. The inarticulate digestive tract is complete with an anus, while the articulate digestive tract is blind, forcing articulates to eject their feces through their mouths. Unlike any articulate brachiopod, at least one group of inarticulates (the lingulids) actively burrows. There are many orders of inarticulate brachiopods, although only the two extant orders (Lingulida and Acrotretida) have fossil records which extend beyond the early Paleozoic.

Ranges of major inarticulate brachiopod groups

Order Lingulida

Lingulids are now, and apparently always have been, shallow burrowing infaunal filter feeders of the shallow intertidal zone. The shell is chitinophosphatic, and characteristically shaped like a fingernail. Note the lophophore and mantle canals visible in the specimen, and the small hairlike setae protruding out of the shell form the edges of the mantle. Lingulids have a muscular pedicle which extrudes out from the posterior of the shell, and a number of antagonistic lateral muscles for manipulating their valves. The animal started its burrow by arching its pedicle up to force the anterior portion of the valves down. It then used contracted the lateral muscles in sequence to move the valves back and forth in a scissors-like motion, and thus burrow down into the sediment. After burrowing down a ways, the animal would alter the trajectory of its burrow so that it eventually burrowed back up to the surface, with the anterior portion of the shell pointed up, and the vulnerable pedicle safely buried in the sediment, helping to anchor the animal (click here to see the lingulid burrowing motion). Sketch and label the important features visible in one of the samples.

Related Websites

• Lingulids (UCMP)

Order Acrotretida

Acrotretids are usually round with a convex, cap-shaped brachial valve, and a flat pedicle valve. Note the internal structures visible in these specimens. How does this internal structure differ from that of bivalves? Like most inarticulate brachiopods, the ones shown here have chitinophosphatic skeletons. However, one important group of acrotretids secretes a calcium carbonate skeleton, and attaches to the substrate by cementing their pedicle valve down.

Related Websites

Class Articulata

(Cambrian-Recent)

Articulate brachiopods were the dominant large hard-bodied marine benthic filter-feeders for most of the Paleozoic. They differ from inarticulate brachiopods in a number of ways. All articulate brachiopods secrete a calcium carbonate shell. The digestive system of articulate brachiopods is blind, there is no anus. The animal must therefore regurgitate its feces in order to get rid of them. The pedicle of the articulate brachiopod is composed of muscle fibers, instead to being and extension of the mantle, as in inarticulates. But perhaps most importantly, articulate brachiopods have an articulated hinge structure in the posterior of the shell which allows the two valves to pivot under minimal muscular exertion. Without the need for all that musculature, more of the internal space could be devoted to the lophophore. The hinge of some brachiopods is straight (strophic), and the valves pivot along the whole hinge line. In others, the hinge line is curve (astrophic), and the valves simply rotate on the teeth. The posterior portion of the hinge structure between the two valves is called the interarea. The left and right portions of the interarea are frequently closed off by plates, leaving a triangular opening through which the pedicle can protrude. An opening in the interarea of the brachial valve is called a notothyrium and an opening in the interarea of the pedicle valve is called a delthyrium. In some types of brachiopod the openings are closed off by more accessory plates to form a circular opening for the pedicle, while in other, free-lying forms, the delthyrium and/or notothyrium are completely closed off. The shells of some brachiopods contain numerous small holes, called punctae, and are defined as punctate. Other brachiopod shells have no little holes, and thus are impunctate, while yet others (basically strophomenids) have what look like holes, but are in fact rods of calcite. This type is called pseudopunctate. In many brachiopods, the plane of commissure (the plane running between the valves) is not flat, but convoluted into folds (which increase the internal volume of the shell) and sulcuses (which decrease the internal volume of the shell).

Articulate brachiopod morphology

Ranges of major articulate brachiopod groups

Order Orthida

(Cambrian-Permian)

The orthid brachiopods were the first articulate group to diversify, and were very common in the early Paleozoic. They are typically strophic (straight hinge line), have biconvex valves, and well developed interareas. Radiating ribs are also common in this group, although this feature is also common in other groups. Most orthids have an open delthyrium and notothyrium, but in some groups these openings are covered by plates. Sulcus and fold structures are common in this group, and can be located in either valve. In general, one valve (usually the brachial valve) is flatter than the other. The cardinalia (structures in the interior of the brachial valve) of orthids are usually simple. Both punctate and impunctate shells are known from this group.

Related Websites

• Orthida (UCMP)

Order Strophomenida

(Ordovician - Triassic)

Strophomenids were an extremely successful Paleozoic group. Specialization within some groups of strophomenids resulted in truly bizarre variations on the basic brachiopod theme. Strophomenids are strophic, as the name would imply, with one concave valve and one convex valve, and the shells are characteristically pseudopunctate. Four suborders of strophomenids are recognized.

Related Websites

• Strophomenids (UCMP)

Order Pentamerida

(Cambrian-Devonian)

Pentamerids can be strophic or astrophic, with impunctate shells. They frequently have a pentagonal shell outline - thus the name. They differ from other articulates in the structure of the posterior portion of the pedicle valve, where pentamerids have a spoon-shaped structure called a spondylium

Related Websites

• Pentamerids (UCMP)

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Order Rhynchonellida

(Ordovician-Recent)

The rhynchonellids are one of two groups of living articulate brachiopods. All rhynchonellids are biconvex, astrophic, and have a fold located in the brachial valve, and a sulcus in the pedicle valve. Strong radiating ribs are common in this group. Only the pedicle valve has an interarea, and its delthyrium is usually partially covered by deltidial plates. The beak of the pedicle valve usually overlaps that of the brachial valve, in order to allow the shell to open and close. The shell of most groups is impunctate. This morphologically conservative group radiated in the Ordovician, and has remained at relatively constant diversity, with some variability, since that time.

Related Websites

• Rhynconellids (UCMP)

Order Spiriferida (Ordovician-Jurassic) The spiriferids are thought to have descended from rhynchonellid ancestors. Members of this group can be punctate or impunctate, strophic or astrophic, and of any of a number of gross shell morphology. The unifying characteristic of the group is that they all possess a particular morphology to the spiral support for their lophophore (spiralia). There are four major groups of spiriferids, three of which (Suborder Atrypidina, Suborder Athyridina, and Suborder Spiriferidina) are presented here. Related Websites Spirifierids (UCMP)

Order Terebratulida

(Devonian-Recent)

Terebratulids are the other living order of articulate brachiopods. They are astrophic and biconvex, commonly circular or ovoid in outline, and have a simple calcareous loop supporting the lophophore. The shell is punctate. Ornamentation is variable in this group - sometimes a single species shows both smooth-shelled and ribbed forms. The interarea is limited to the pedicle valve, and has a circular pedicle opening, or foramen, located in the beak. While terebratulids belong to the same phylum as many ancient lineages, the living terebratulids are thoroughly modern, and have been found to out-perform molluscan bivalves in filter feeding efficiency under certain conditions. The characteristic shape of terebratulids resembles that of ancient oil lamps, and thus the common name for brachiopods is "lamp-shells".

Related Websites

• Terebratulids (UCMP)

Boardman, R.S. and Cheetham, A.H., 1987. Phylum Bryozoa. in Boardman, R.S., Cheetham, A.H., and Rowell, A.J. (eds.). Fossil Invertebrates. Blackwell Scientific Publications. 713 pp.

Boardman, R.S., and Cheetham, A.H. 1973. Degrees of colony dominance in stenolaemate and gymnolaemate Bryozoa. in Boardman, R.S., Cheetham, R.S., and Oliver, W.A., Jr., (eds.), Animal colonies: development and function through time. Dowden, Hutchinson, and Ross, Stroudsburg, PA.

Durto, J.T. and Boardman, R.S., (eds.) 1981. Lophophorates-notes for a short course. University of Tennessee Dept. of Geol. Sci. Studies in Geology 5.

McKinney, F.K. 1989. Feeding and associated colonial morphology in marine bryozoans. Reviews in aquatic sciences 2: 255-280.

McKinney, F.K, and Jackson, J.B.C., 1989. Bryozoan evolution. Unwin Hyman, Boston.

Ryland, J.S. 1976. Physiology and ecology of marine bryozoans. Advances in marine biology 14: 285-443.

Ryland, J.S., 1970. Bryozoans. Hutchinson University Library, London.

Woollacott, R.M. and Zimmer, R.L., (eds), 1977. Biology of bryozoans. Academic Press, Inc., New York.

Rowell, A.J. and Grant, R.E., 1987. Phylum Brachiopoda. in Boardman, R.S., Cheetham, A.H., and Rowell, A.J., (eds.). Fossil Invertebrates. Blackwell Scientific Publications. 713 pp.

Rudwick, M.J.S. 1970. Living and fossil brachiopods. Hutchinson and Co., Ltd., London.