Stenolaemata are a

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

of exclusively marine

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a ...

ns. Stenolaemates originated and diversified in the

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

, and more than 600 species are still alive today.Stenolaemata.
The Digital Atlas of Ordovician Life. All extant (living) species are in the order

Cyclostomatida Cyclostomatida, or cyclostomata (also known as cyclostomes), are an ancient order of stenolaemate bryozoans which first appeared in the Lower Ordovician. It consists of 7+ suborders, 59+ families, 373+ genera, and 666+ species. The cyclostome b ...

, the third-largest order of living bryozoans.Ramalho, L. V., G. Muricy, and P. D. Taylor. (2009)
Cyclostomata (Bryozoa, Stenolaemata) from Rio de Janeiro State, Brazil.
''Zootaxa'' 2057 32-52. These animals are stationary suspension feeders that live on the ocean floor. They formed colonies with robust,

calcified Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue,Miller, J. D. Cardiovascular calcification: Orbicular origins. ''Nature Ma ...

exoskeletons An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

, allowing for a high potential for fossil preservation. The individual zooids in the colony may be tubular, conical, or sac-shaped. Each individual, or

zooid A zooid or zoöid is a single animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zoo ...

, may extend from the colony at an angle, extending its tentacles to feed. The fossil genus ''Batostoma'' in the order

Trepostomatida Trepostomatida (the trepostomates) is an extinct order of bryozoans in the class Stenolaemata. Trepostome bryozoans possessed mineralized calcitic skeletons and are frequently fossilized; some of the largest known fossilized bryozoan colonies ...

existed in monticular colonies. Stenolaemates were the predominant bryozoan group during the

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

, when many extinct orders proliferated within the class. Some grew as lacy or fan-like colonies that became important

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock o ...

builders, and in some regions form an abundant component of

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

s. The extinct Palaeozoic stenolaemate orders are placed in the superorder

Palaeostomata Palaeostomata is a superorder of extinct stenolaemate bryozoans, including all extinct orders within Stenolaemata and excluding the order Cyclostomata Cyclostomi, often referred to as Cyclostomata , is a group of vertebrates that comprises t ...

. Their numbers were greatly reduced during the terminal Permian extinction event, and most stenolaemates were extinct by the start of the Jurassic. However, the basal and previously rare stenolaemate order Cyclostomatida diversified in the Jurassic and became the most abundant group of bryozoans in the late Mesozoic. Cyclostomatida is no longer the most speciose bryozoan group, as the order experienced high rates of extinction during the end-Cretaceous mass extinction, while

ctenostome The Ctenostomatida are an order of bryozoans in the class Gymnolaemata. The great majority of ctenostome species are marine, although ''Paludicella'' inhabits freshwater. They are distinguished from their close relatives, the cheilostomes, by t ...

and

cheilostome Cheilostomatida, also called Cheilostomata, is an order of Bryozoa in the class Gymnolaemata. They are exclusively marine, colonial invertebrate animals. Cheilostome colonies are composed of calcium carbonate and grow on a variety of surfaces, ...

bryozoans in the class

Gymnolaemata Gymnolaemata are a class of Bryozoans. Gymnolaemata are sessile, mostly marine organisms and grow on the surfaces of rocks, kelp, and in some cases on animals, like fish. Zooids are cylindrical or flattened. The lophophore is protruded by action ...

diversified around the same time. Nevertheless, cyclostomates are still major components of modern marine ecosystems. Extant and extinct orders in this class include: *

/Cyclostomata (Ordovician-present) *

Cryptostomata Cryptostomata is an order of fossil bryozoans that lived from the Ordovician to the Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous P ...

/Cryptostomida † (Ordovician-Triassic) *

Cystoporata Cystoporata, also known as Cystoporida or cystoporates, are an extinct order of Paleozoic bryozoans in the class Stenolaemata. Their fossils are found from Ordovician to Triassic strata. All cystoporatan bryozoan genera (around 50 or so) have ...

/Cystoporida † (Ordovician-Triassic) * Esthonioporata † (Ordovician-Devonian) *

Fenestrata Fenestrata is an extinct order of bryozoan, dating from the Upper Arenig In geology, the Arenig (or Arenigian) is a time interval during the Ordovician period and also the suite of rocks which were deposited during this interval. History T ...

/Fenestrida † (Ordovician-Permian) * Timanodictyina † (Devonian-Permian, may be a suborder of Cryptostomata) * Trepostomata/

† (Ordovician-Triassic)

References

External links

*Bock, P. (2015)
Stenolaemata.
''In'': Bock, P.; Gordon, D. (2015). World List of Bryozoa. Accessed through the World Register of Marine Species.
Stenolaemata.
Fossil works. Extant Ordovician first appearances Protostome classes {{bryozoan-stub