Bryozoan Orders

(After McKinney, F.K. & Jackson, J.B.C. 1989. Bryozoan Evolution. Boston, Unwin Hyman)

Links for Sections are to the Systematic Index of Families; links for terms in the text are to the glossary.

Class Stenolaemata

Zooids are elongate cylindrical and continue to lengthen through ontogeny, with long axis at angle to local colony growth direction; basal and vertical walls rigidly calcified; interzooidal communication through space between outer ends of vertical walls in most, but through pores in vertical walls in some; membranous sac encloses polypide and is deformed to protrude lophophore through orifice at outer end of skeletal tube. Lower Ordovician - Recent.

Order Cyclostomata

Also termed Tubuliporata

Colonies encrusting or erect; autozoooids commonly long, some with basal diaphragms and other structures; skeletal structure typically laminated, many with communication pores; gonozooids common, kenozooids or nanozooids in some; extrazooidal skeleton may be present. Upper Ordovician - Recent.

Order(?) Hederellida

A group of bryozoans similar to cyclostomatids; of uncertain systematic placement. Late Ordovician - Carboniferous.

Order Cryptostomida

Colonies erect arborescent, or bilaminar sheets; generally short autozooids, some with basal diaphragms or hemisepta (incomplete lateral partitions). Skeletons without communication pores, typically laminated; kenozooids or extrazooidal skeleton may be present. Lower Ordovician - Upper Permian (or Cretaceous?).

Order Cystoporida

Colonies encrusting or erect, autozooids short and without, or long and with, basal diaphragms; most autozooids with thickened strip (lunarium) of different microstructure along one side in thick-walled outer zone; skeletal structure laminated, granular or granular-prismatic, some with communication pores; kenozooids in some, gonozooids uncommon; vesicular extrazooidal skeleton common and abundant. Lower Ordovician - Upper Permian (or Cretaceous?).

Order Trepostomatida

Colonies encrusting or erect; autozooids generally containing basal diaphragms and commonly other lateral structures; kenozooids common, extrazooidal skeleton in some; skeletons without communication pores, typically laminated. Lower Ordovician to Upper Triassic (or Recent?).

Order Fenestrida

Colonies erect, composed of narrow unilaminate branches; short autozooids commonly with hemisepta, but basal diaphragms in very few; primary zooidal without communication pores, typically granular; heterozooids (gonozooids, nanozooids, and various others) in some; extrazooidal skeleton extensive, several times autozooidal skeleton in volume, consisting of laminae penetrated by small granular rods. Lower Ordovician to Upper Permian or Triassic. (Although Admiratella is reported from the Cretaceous)

Class Gymnolaemata

Zooids generally box- to sac-shapes or short cylinders, with long axis roughly parallel to colony growth direction; zooidal size is fixed early in ontogeny; zooidal body walls entirely organic to rigidly calcified; interzooidal communication by funicular network through tissue-plugged pores in vertical walls; vertical or frontal walls deformed to protrude polypide. Upper Ordovican - Recent.

Order Ctenostomata

Zooidal walls membranous or gelatinous; orifice terminal and closed by pleated collar in most; heterozooids absent, or only kenozooids. Upper Ordovician - Recent.

Order Cheilostomata

Zooidal walls calcified, flexible or rigid; orifice frontal and closed by proximal hinged operculum; heterozooids usually present, commonly diverse; suborders based upon frontal calcification and mechanism of lophophore protrusion. Upper Jurassic - Recent.

Class Phylactolaemata

Colony gelatinous or membranous, without mineralised skeleton; zooid organs suspended in confluent body cavity of colony; tentacles in circular or bilobed row around mouth. Reproduction mainly from asexually produced statoblasts. Freshwater. Fossil statoblasts recorded from Early Cretaceous, Late Tertiary, and Quaternary. (After Boardman & Cheetham,1987)

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Edited by Phil Bock
Modified on 6th July 2000
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