Stenolaemata are a

class Class, Classes, 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 d ...

of exclusively marine

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

ns. Stenolaemates originated and diversified in the

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

, 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 ...

, 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

exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...

s, 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 an 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 zooids can ...

, may extend from the colony at an angle, extending its tentacles to feed. The fossil genus ''Batostoma'' in the order Trepostomatida existed in monticular colonies. Stenolaemates were the predominant bryozoan group during the

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

, 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 component, abiotic (non-living) processes such as deposition (geol ...

builders, and in some regions form an abundant component of

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

s. The extinct Palaeozoic stenolaemate orders are placed in the superorder Palaeostomata. 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 and cheilostome bryozoans in the class Gymnolaemata 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/Cryptostomida † (Ordovician-Triassic) * Cystoporida/Cystoporata † (Ordovician-Triassic) * Esthonioporata † (Ordovician-Devonian) * Fenestrata/Fenestrida † (Ordovician-Permian) * Timanodictyina † (Devonian-Permian, may be a

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

of Cryptostomata) * Trepostomatida/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. {{Authority control Extant Ordovician first appearances Protostome classes