A

abdomen (Sabellida & Serpulidae):
body region posterior to the thorax; recognised by notopodial (dorsal) uncini and neuropodial (ventral) chaetae.

accessory gills (Spionidae):
see branchiae.

acicular spine (Spionidae):
straight thick chaetae in notopodia of posterior segments.

acicular uncini (Sabellidae):
nearly straight uncini with a poorly developed breast and a long handle.

anal depression (Sabellidae):
dorsoventrally flattened expansion of posterior abdominal segments, accompanied in some species by lateral flanges.

anterior peristomial ring (Sabellidae):
anterior part of the peristomium, attached to the radiolar lobe; ventral anterior lobe can be triangular or rounded.

apron (Serpulidae):
membranous flap formed by thoracic membranes joined ventrally past the last thoracic chaetigers.

avicular uncini (Sabellidae):
Z-shaped uncini with well developed breast and a handle.

B

bayonet chaetae (Serpulidae):
collar chaetae with one or two (sometimes more) large proximal bosses (or “teeth”) at the base of a distal limbate zone.

bayonet chaetae (Sabellidae):
small, thin, and slightly bent narrowly hooded (see limbate) thoracic and abdominal chaetae.

bifurcated:
divided into two parts or branches.
bilimbate:
chaetae with a hood (limbus) visible on both sides of the shaft, see limbate.
branchiae (Spionidae):
paired body appendages on segments provided with blood loop for respiration. N.B. different from radiolar crown of Sabellida.

breast:
rounded part of a sabellid and serpulid uncini, located below the main fang in Sabellidae or anterior fang (peg) in Serpulidae. Uncini with well- developed breast are avicular (Sabellidae).

broadly hooded (Sabellidae, Serpulidae):
hooded capillaries with the distal hood (limbus) enlarged on both sides of the shaft and looking bilimbate under the compound microscope.

C

capillary chaetae:
slender, often long, chaetae tapering to a fine point; the term has been used as collective term for elongate, needle-like or hair-like chaetae of otherwise variable shape and ontogeny.

caruncle (Spionidae):
a dorsal extension of prostomium, as an elevation or as a distinct crest.

chaeta (pl. chaetae):
chitinous bristle protruding from an epidermal pocket in the body wall.

chaetal inversion (Sabellida):
the thorax bears chaetae dorsally (in notopodia) and uncini ventrally (in neuropodia), in the abdomen the position of chaetae and uncini is reversed.

chaetiger:
segment bearing chaetae.

cirrus (pl. cirri):
soft tactile appendage, usually in polychaete parapodia

cirriform (Spionidae):
pygidium with cirri.

companion chaetae (Sabellidae):
chaetae arranged in a single row, parallel to the row of thoracic uncini, with a basal shaft and a distal membrane.

collar (Sabellidae, Serpulidae):
an encircling membranous fold or flap projecting from the peristomium and, in some cases, covering the base of the radiolar crown.

collar chaetae (Sabellidae, Serpulidae):
notochaetae of the first (collar) segment not accompanied by neuropodial uncini.

collar segment (Sabellidae, Serpulidae):
First chaetiger, often bearing a membranous collar and notochaetae (see collar chaetae), but lacking uncini.

constriction (Serpulidae):
narrowing of the opercular peduncle at basis of opercular funnel or ampulla.

constriction (Spionidae):
narrowing of the upper part of hook shaft.

D

distal wings (Serpulidae):
paired lateral outgrowths of the peduncle located just below the operculum – see peduncular wings.

dorsal:
pertaining to, or situated at the back, or dorsum.

dorsal lips (Sabellidae):
paired rounded lappets on dorsal margin of mouth, used for tube building and sorting out the particles collected by the radiolar crown.

dorsal radiolar appendages:
modified radioles fused to dorsal lips.

F

falcate spines (Spionidae):
chaetae resembling mammalian canine teeth, characteristically present in the posterior row-notochaetae of segment 5 in polydorin spionids.

faecal groove (Sabellidae, Serpulidae):
ciliated channel running along the body and used for directing the faeces from the anus to the tube opening.

faecal groove inversion:
change in the position of the ciliated groove used to direct faeces from the anus to the tube mouth: it runs ventrally in the abdomen passing between the last thoracic notopodia and first abdominal neuropodia and becomes dorsal in the thorax.

flat-trumpet-shaped chaetae (Serpulidae):
in profile resembling a hollow trumpet with distal expanded part edged with two rows of teeth. However, examination with SEM shows that these chaetae are flat, with a single row of marginal acute teeth.

funnel (Serpulidae):
descriptive term used to indicate the inverted cone-like proximal part of the operculum in Hydroides and the entire operculum in Serpula.

G

glandular girdle (Sabellidae):
complete or incomplete pale ridge around the first or second segment.

H

handle (Sabellidae):
posterior elongated extension of an uncinus, always embedded in tissue.

hood (Sabellidae, Serpulidae):
distal extension of capillary chaetae appearing as a flattened longitudinal flange (see limbus) under the compound microscope, but made of tightly packed microfibrilles as seen under SEM.

hood (Spionidae):
a thin sheath surrounding the dentate end of hooks.

hooks (Spionidae):
distally curved chaetae used to hold individual inside the burrow or tube.

I

inter-radiolar membrane (Sabellidae, Serpulidae):
membrane connecting basal parts of radioles.

inter-ramal eyespots (Sabellidae):
simple eyes located between the rami (notopodia and neuropodia) in both thoracic and abdominal segments.

K

keel (Serpulidae):
outer longitudinal prominent ridge running along the calcareous tube length.

L

lappet:
lobe or flap-like projection.
lateral:
locate on side.
lateral flange (Spionidae):
small subdistal structure on heavy falcate spines in polydorin spionids.

limbate:
condition of chaetae, in which a distal longitudinal flange (limbus) appears to be present; however, this is an artifact of light microscopy, same as hooded, see hood.

limbus:
flattened distal border of chaetae, longitudinal flange (Latin = edge, border), however, see hood.
lobate:
subdivided into lobes.

M

main fang (Sabellidae):
very large anterior fang of an uncinus; surmounted by rows of much smaller teeth.

male horns (Spionidae):
paired dorsal appendages on segment 2 in adult males of Pygospio.

median antennae:
see occipital antennae.

N

narrowly hooded (Sabellidae):
capillary chaetae with the distal hood (limbus) only on one side of the shaft; see limbate.

neurochaetae:
chaetae of neuropodia.

neuropodium ( pl. neuropodia):
ventral branch or ramus of a parapodium.

notochaetae:
chaetae of a notopodium.

notopodium (pl. notopodia):
dorsal branch or ramus of a parapodium.

nuchal organs (Spionidae):
sensory prostomial organs in polychaetes; bands of numerous very short cilia on both sides of the caruncle.

nuchal papillae (Spionidae):
see occipital antennae.

O

occipital antenna (Spionidae):
short median prostomial appendages.

operculum (pl. opercula) (Serpulidae):
tip of modified radiole used to plug the tube when the worm is retracted.

opercular endplate (Serpulidae):
terminal reinforcement of opercular ampulla, often chitinous or calcareous.

P

paleate (Sabellidae):
broadly hooded (bilimbate) capillaries with the shaft not reaching the tip of the chaetae.

palmate:
having lobes radiating from a common point.
palps:
a pair of feeding and/or tactile organs arising from the head or anterior end of a polychaete.

parapodium (pl. parapodia):
fleshy lateral projection from a body segment which usually bears chaetae.

peduncle (Serpulidae):
modified radiole bearing the operculum.

peduncular wings:
collective term for all flattened lateral wing-like appendages of peduncle.

peristome (Serpulidae):
collar-like widening of tube, former tube mouth.

peristomium:
anterior region of the polychaete body located posterior to prostomium and surrounding the mouth.

pinnules (Sabellidae, Serpulidae):
small ciliated paired outgrowths located along from the inner edge of the radioles, giving each radiole a feathery appearance.

prostomium:
anteriormost, presegmental region of body, bearing the radioles and sometimes eyes.
posterior peristomial ring (Sabellidae, Serpulidae):
posterior part of the peristomium; may bear a membranous collar.
pseudoperculum (pl. pseudopercula) (Serpulidae):
modified radiole, generally without pinnules; can develop into a new functional operculum when the functional operculum is lost.

pygidium:
post-segmental terminal body-part surrounding the anus.

R

radiolar crown (Sabellidae, Serpulidae):
anterior part of prostomial origin extended outside the tube and used for feeding and respiration; made of pinnulated radioles attached to radiolar lobes around the mouth.

radiolar eyes (Sabellidae, Serpulidae):
ocelli found in the radiolar crown that can vary in number, arrangement and structure.

radiolar flanges (Sabellidae):
paired, lateral membranous extensions along outer margins of radioles.

radiolar lobes (Sabellidae, Serpulidae):
proximal part of the radiolar crown attached to the anterior end of the body; generally as two semicircles located on both sides of the mouth, but forming spirals in some species.

radioles:
filaments making up the radiolar crown; attached to the radiolar lobes and bearing rows of paired ciliated pinnules (Sabellida).

radius (pl. radii) (Serpulidae):
radial projection of the funnel (Hydroides and Serpula only).

rasp-shaped uncini (Sabellidae, Serpulidae):
with two or more rows of teeth.

recurved spines (Spionidae):
heavy chaetae with distal parts bent backwards, found in notopodia of posterior segments

S

saw-shaped uncini (Serpulidae):
with only one row of teeth.

sedentary:
attached to a surface and not moving freely.
segment:
one of the serially repeated units comprising the trunk; often separated internally by septa or dissepiments.

shaft:
proximal smooth part of chaetae, partly embedded in the tissue, also see handle.
spine-like chaetae:
narrowly hooded (also see limbate) capillaries.

spinule (Serpulidae):
each of the tubercular or tooth-like projections of a spine in the verticil of the genus Hydroides. By their position relative to the axis, spinules may be internal, lateral, or external. By their position along the spine, spinules may be proximal, medial, or distal.

Spirobranchus-type chaetae (Serpulidae):
special collar chaetae with a “fin” positioned below the distal limbus (hood) and consisting of numerous tiny hair-like spines.

stylodes (Sabellidae, Serpulidae):
outward projections from the outer margin of radioles that can be digitiform (cylindrical or finger-like), strap-like (flattened) or palmate (branched and flattened); always paired in Sabellidae, unpaired in Serpulidae.

T

thoracic membranes (Serpulidae):
thin folds on both sides of thorax, extending from dorsal part of collar to lateral and/or ventral side of posterior thorax..

thorax:
anterior region of the body behind the head.

tonguelet (Serpulidae):
special form of lappet, between dorso-lateral and ventral lobes of the collar in some serpulid genera.

torus (pl. tori) (Sabellidae, Serpulidae):
transverse elevation of parapodium surrounding the uncini.

triangular depression (Serpulidae):
depressed area between thoracic uncinigerous tori when gradually approaching and almost touching one another posteriorly and ventrally.

true trumpet-shaped chaetae (Serpulidae):
distally hollow chaetae, with two parallel rows of sharp denticles, extending into a long lateral spine.

tube:
protective structure completely enclosing polychaete bodies; made of mucus often covered by sediments particles (Sabellidae, Spionidae) or calcium carbonate (Serpulidae, exceptionally Sabellidae).

U

uncinigerous:
bearing uncini
uncinus (pl. uncini) (Sabellidae, Serpulidae):
small modified hook-shaped or comb-shaped chaeta deeply embedded into tissue with only its dentate edge protruding from the body wall; uncini usually arranged in tori, elevated rows transverse to the axis of the animal.

V

ventral:
relating to or situated on or close to the abdomen; side of the polychaete body bearing the mouth.

ventral lips (Sabellidae):
membranous lappets on both sides of mouth.

ventral radiolar appendages (Sabellidae):
modified radioles generally lacking pinnules located on the ventral edge of the radiolar lobes.
ventral sacs (Sabellidae):
vesicles filled with sediment used for tube building; located between the radiolar lobes.

ventral shields (Sabellidae, Serpulidae):
epidermal glandular areas on ventral side of the thorax, well-defined or diffused.

verticil (Serpulidae):
distal part (usually a crown of chitinous spines) of operculum in Hydroides.

verticil spine (Serpulidae):
any of the radial elements, generally around a central disc, together forming the verticil in Hydroides.