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Pectinariidae
Description
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Pectinariids are characterised by having a reduced
prostomium which is completely fused to the peristomium;
the latter is reduced to lips around the mouth. Antennae are
absent. The peristomial palps (buccal tentacles) are grooved
and inserted on or around the lips, and cannot be retracted into
the buccal cavity. A cephalic veil (tentacular
membrane) is present, and nuchal organs appear to be
represented by dorsal ciliated crests. The longitudinal muscles are grouped in
bundles. Segmentation is distinct and the first segment is
completely fused to the head and bears golden notopodial
paleae. Other notopodia are short, truncate
cylinders; the neuropodia are tori. Anteriorly, two pairs of
dorsal, branching branchiae are present. Lateral organs are
present, as internally ciliated pits between the
notopodia and neuropodia. There is a ventral buccal organ and
the gut is looped. A gular membrane, between two anterior
segments, is present. Nephridia are mixonephridia, comprising a few pairs of anterior nephridia and
posterior gonoducts. The circulatory system is closed, and
heart body is present. The posterior end is a flattened scaphe
with spine-like chaetae. Aciculae are absent. Chaetae are
present as notopodial capillaries, spines (paleae)
and neuropodial uncini. The worms live in
cone-shaped tube of unique shape and construction.
The above description is taken from Hutchings (2000) which is based on Fauchald and Rouse (1997).
Identification tips
Recognising the family
Pectinariids should be easily recognised by their distinctive golden paleae
(large flattened chaetae) which surround the mouth. Their tube is also distinctive and resembles an ice-cream cone made of cemented sand grains.
Distinguishing species
Characters used to distinguish genera and species include: the degree of
fusion of the cephalic veil to the operculum; the marginal
ornamentation of the cephalic veil and the operculum; the
number of uncinigerous segments; the number of
rows of vertical teeth on the uncini and the presence or
absence of scaphal papillae and their shape.
Description | Identification
tips | Natural History | Diversity
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