Glossary of Special Terms

(adapted from Hayward & Ryland, 1985 and Hayward & Ryland, 1999)

Adventitious avicularium: One occupying a position on the frontal shield of an autozooid.

Alveoli: Extrazooidal spaces between the autozooids of rectangulate cyclostomes.

Ancestrula: First-formed zooid of a colony, derived by metamorphosis of a free-swimming larva.

Anter: Part of the orifice distal to the condyles in ascophoran cheilostomes.

Apertural bar: Fused pair of costae immediately proximal to the orifice in cribrimorph cheilostomes.

Areolar pore: Marginal pore in the frontal shield of some cheilostomes.

Ascopore: Marginal frontal pore/s which serves as inlet of the ascus in some ascophoran cheilostomes.

Ascus: Sac-like hydrostatic organ in ascophoran cheilostomes, that fills with seawater when the tentacles are protruded.

Autozooid: Feeding zooid.

Avicularium (pl. Avicularia): Specialised zooid in cheilostomes with reduced polypide but strong muscles which operate a hypertrophied, mandible-like operculum.

Basal: Underside of an encrusting or freely-living colony.

Basal lamina: Basal wall of the cyclostome colony visible at the growing edge.

Bifoliate: Colony formed of two layers of zooids back-to-back.

Cancelli: Kenozooids or extrazooidal spaces between the autozooids of cancellate cyclostomes.

Capitulum: The apical group of autozooids in pedunculate species of cyclostomes.

Cauda: Thread-like proximal gymnocyst of club-shaped cheilostome autozooid.

Condyle: One of a pair of oppositely placed tooth-like protuberances on which the operculum pivots in the orifice of ascophoran cheilostomes.

Connate: Describing groups of autozooids arranged in linear rows, with the erect, peristomial portions fused in rigid, comb-like series in some cyclostomes.

Costa: Modified spine overarching the frontal membrane in cribrimorph cheilostomes; usually united with neighbouring costae to form a frontal shield spinocyst.

Costate shield or Spinocyst: The frontal wall of cribrimorph ascophorines, formed from series of fused costae.

Cryptocyst: More or less horizontal calcareous lamina of the frontal interior wall in cheilostomes.

Distal: Pertaining to the side away from the ancestrula or origin of colony growth.

Ectooecium: Outer layer of ooecial wall.

Entooecium: Inner layer of ooecial wall.

Entosaccal cavity: That part of the body cavity of cyclostome autozooids enclosed by the membranous sac and the outer body wall; regarded as a pseudocoel.

Exterior wall: The outer body wall of the autozooid, including the cuticle and adjacent epithelium and calcified structures.

Extrazooidal: Structures not referable to a single zooid.

Fasciculate: Describing an arrangement of autozooids in which groups of erect peristomial portions are fused in bundles called fascicles.

Fenestra: Uncalcified area in the ectooecium through which the entooecium is visible.

Fenestrule:  Open space in reticulate colony.

Fixed-walled: Skeletal organisational grade in cyclostomes in which the zooid has a calcified exterior frontal wall.

Free-walled: Skeletal organisational grade in cyclostomes in which the zooid lacks a calcified exterior frontal wall and retains hypostegal pseudocoelomic connection with neighbouring zooids over the distal ends of their interior walls.

Frontal: Pertaining to the orifice-bearing side of zooid or colony.

Frontal membrane: Uncalcified part of frontal body wall in cheilostomes.

Frontal shield: The calcified frontal surface of an ascophoran zooid.

Gonozooid: Zooid modified as an embryonic brood chamber.

Gymnocyst: Calcified frontal shield formed of exterior calcification in cheilostomes.

Heterozooid: Specialised zooid unable to feed.

Hypostegal coelom: An extension of the main coelom overlying the frontal shield in some ascophoran cheilostomes.

Hypostegal pseudocoelom: Body cavity in cyclostomes connecting neighbouring zooids over the distal ends of their interior walls.

Interior wall: Calcified internal walls or partitions not bounded by the zooid cuticle and overlain by epithelium and coelom or pseudocoel.

Internode: Solid branch between the elastic nodes of articulated colonies.

Interzooidal avicularium: One which extends to the basal surface of the colony, but is wedged between autozooids rather than replacing one of them.

Kenozooid: Heterozooid without a polypide or operculum/mandible.

Lophophore: The ring of tentacles surrounding the mouth of the zooid.

Lyrula: Median tooth, often anvil-shaped, on the proximal side of the orifice in some cheilostomes.

Mandible:  Avicularian equivalent of the operculum of an autozooid, seldom calcified.

Manticule: Mound on the colony surface, indicating the position of an exhalent chimney.

Maternal zooid: The proximal reproductive zooid from which ova pass to an ovicell.

Mucro: A blunt or spinous elevation of the (usually proximal) lip of the orifice in some cheilostomes.

Nanozooid: Dwarf zooid containing reduced polypide in some cyclostomes.

Node: Elastic joint between the solid branches in articulated colonies.

Occlusor muscles: Muscles closing the operculum.

Ooeciopore: The opening of the gonozooid, through which larvae are released.

Ooeciostome: The tubular growth containing the ooeciopore.

Operculum: A generally uncalcified lamina, hinged or pivoting on condyles, which closes the zooidal orifice in cheilostomes, seldom calcified.

Opesia: The main opening in the skeleton of an anascan cheilostome zooid.

Oral: Pertaining to the orifice of a bryozoan zooid (not to the mouth).

Oral spine: Spines located around the distal edge of the orifice, often basally articulated.

Orifice: Opening in the zooid through which the lophophore is extended in cheilostomes.

Ovicell: The globular brood chamber of many cheilostomes.

Peristome: Elevated rim or tube surrounding the cheilostome orifice or cyclostome aperture.

Polymorph: Name applied to zooid types in colonies possessing more than one kind of zooid.

Polypide: Those organs and tissues in a bryozoan autozooid which undergo periodic replacement; i.e. the tentacles, tentacle sheath, alimentary canal, associated musculature and nerve ganglion.

Pore chamber: Small chambers developed basally around the perimeter of the zooid in some cheilostomes.

Poster: Part of the orifice in ascophoran cheilostomes proximal to the condyles and leading to the ascus.

Protoecium: The proximal, hemispherical portion of the cyclostome ancestrula derived directly from the metamorphosed larva.

Proximal: Pertaining to the side toward the ancestrula or origin of colony growth.

Pseudopore: Tissue filled pore in the calcification of the zooidal exterior wall in cyclostomes closed by the outer cuticle; or pore between the main (visceral) and hypostegal coelom in the frontal shield of some cheilostome zooids.

Pseudosinus: A notch or hole in the the peristome of some ascophoran cheilostomes.

Retractor muscles: Muscles arising from the proximal end of the zooid, inserted on the pharynx and the base of the lophophore, serving to withdraw the polypide.

Rosette-plate: Multiporous subcircular area in vertical walls of cheilostomes for the passage of mesenchymatous fibres between zooids.

Rostrum: Distal part of the avicularium occupied by the mandible.

Secondary orifice: In those cheilostome species with an immersed primary orifice, the outer opening of the peristome.

Sinus: Slit at proximal edge of orifice in some ascophoran cheilostomes.

Tatiform: A cheilostome ancestrula with a membranous frontal wall, usually surrounded by spines.

Umbo (pl. Umbones): A blunt prominence on the frontal shield or ovicell in some cheilostomes.

Vibraculum: Variety of avicularium in cheilostomes with an operculum in the form of a long seta slung between condyles.

Vicarious avicularium: One that replaces an autozooid in a series and is approximately the same size.

Zoarium: Calcified skeleton of the colony.

Zooeciule: Small cheilostome zooid with orifice but not all of the parts of an autozooid.

Zooecium (pl. Zooecia): Calcified skeleton of a bryozoan zooid.

Zooid: Single bryozoan individual.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith