Editing Parapodium (section)

==Annelid parapodia==
[[File:Annelid parapodium anatomy.jpg|thumb|upright=0.8|An image plate showing the different anatomical features (dashed outline) of a representative annelid parapodium. Parapodium is from [[Lepidonotus|''Lepidonotus oculatus'']] and is a Museums Victoria specimen.]]
[[File:Arctonoe sp. parapodium with chaetae labels.png|upright=1.5|thumb|Microscope photograph of a parapodium from a specimen of ''[[Arctonoe]]'' 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|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 and locomotion.<ref>{{cite book |last1=Rouse |first1=Greg |last2=Pleijel |first2=Frederick |title=Polychaetes |date=2001 |publisher=Oxford University Press |location=Oxford |isbn=0198506082}}</ref>

===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 [[Dorsum (biology)|dorsal]] lobes are called notopodia and the [[ventral]] lobes neuropodia. Both neuropodia and notopodia may possess a bundle of [[Chaeta|chaetae]] (neurochaetae and notochaetae respectively), 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 [[Cirrus (biology)|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 (Annelida)|elytron]]). <ref>{{cite book |last1=Hutchings |first1=P. A. |last2=Fauchald |first2=K. |title=Polychaetes and Allies: the Southern Synthesis - Class Polychaeata: Definition and General Description |date=2000 |publisher=CSIRO Publishing |location=Melbourne |pages=1–3}}</ref>

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===
{| class="wikitable"
|-
! Component !! Description
|-
| '''Dorsal cirrus''' || [[Cirrus (biology)|Cirrus]] extending from the notopodium; can be modified into a [[Elytron (Annelida)|scale]] (or elytron) in scale worms.
|-
| '''Neuroaciculum''' || Stout internal supporting chaeta ([[acicula]]) for the neuropodium
|-
| '''Neurochaetae''' || [[Chaeta|Chaetae]] of the neuropodium 
|-
| '''Neuropodium''' || Ventral lobe
|-
| '''Notoaciculum''' || Stout internal supporting chaeta ([[acicula]]) for the notopodium
|-
| '''Notochaetae''' || [[Chaeta|Chaetae]] of the notopodium 
|-
| '''Notopodium''' || Dorsal lobe
|-
| '''Ventral cirrus''' || [[Cirrus (biology)|Cirrus]] extending from the neuropodium
|}
{{clear}}