and is a Museums Victoria specimen. '' sp. showing the internal acicula that support the two lobes of the parapodium. This parapodium is from a Museums Victoria specimen. Most species of
polychaete annelids have paired, fleshy parapodia which are segmentally arranged along the body axis. Parapodia vary greatly in size and form, reflecting a variety of functions, such as, anchorage, protection, locomotion, feeding and breathing.
General description Parapodia in
polychaetes can be
uniramous (consisting of one lobe or ramus) but are usually
biramous (two lobes or rami). In the latter case, the
dorsal lobes are called notopodia and the
ventral lobes neuropodia. Both neuropodia and notopodia may possess a bundle of
chaetae (neurochaetae and notochaetae respectively, a chaetae-bearing parapodium is called
chaetiger), which are highly specific and greatly diversified. A single stout internal chaeta, called an
acicula, may be present in each lobe, which are used to support well-developed parapodia. Notopodia and neuropodia can also bear
cirri which are tentacle-like projections of the parapodia. In some groups, such as the scale worms (e.g.
Polynoidae), the dorsal cirrus is modified into a scale (or
elytron). In most species, the anteriormost segments may be specialised into the head region and
prostomium, which can result in the modification of those parapodia, loss of chaetae and elongation of the cirri into anterior-facing tentacular cirri.
Glossary of components of the parapodium ==Gastropod parapodia==