Nuchal organ

The nuchal organ, indicated by "no". Source: [1]

The nuchal organ is a ciliated pit[1] or groove present at the posterior end of the prostomium of annelid worms,[1] some cephalopods,[2] and other invertebrates.[3]

Annelids only possess one nuchal organ, although the nature of the grooving may make it appear to be a pair of organs.[4]

It may be involved in light detection,[2] and may have a role in food detection and mating.[5]

## References

[edit]

1. ^ a b c Hessling, R.; Purschke, Günter (23 October 2000). "Immunohistochemical (cLSM) and ultrastructural analysis of the central nervous system and sense organs in Aeolosoma hemprichi (Annelida, Aeolosomatidae)". Zoomorphology. 120 (2): 65–78\. doi:10.1007/s004350000022. S2CID 38957268.
2. ^ a b Parry, Matthew (October 2000). "A description of the nuchal organ, a possible photoreceptor, in Euprymna scolopes and other cephalopods". Journal of Zoology. 252 (2): 163–177\. doi:10.1111/j.1469-7998.2000.tb00612.x.
3. ^ Peñalva-Arana, Carolina D.; Manca, Marina (1 August 2007). "An SEM study of the nuchal organ in Daphnia himalaya (nov. sp.) embryos and neonates collected from the Khumbu region (Nepalese Himalayas)" (PDF). Journal of Limnology. 66 (2): 153. Bibcode:2007JLimn..66..153P. doi:10.4081/jlimnol.2007.153.
4. ^ Purschke, G.; Wolfrath, F.; Westheide, W. (21 March 1997). "Ultrastructure of the nuchal organ and cerebral organ in Onchnesoma squamatum (Sipuncula, Phascolionidae)". Zoomorphology. 117 (1): 23–31\. doi:10.1007/s004350050026. S2CID 39830837.
5. ^ Schlötzer-Schrehardt, U. (December 1986). "Ultrastructural investigation of the nuchal organs of Pygospio elegans (Polychaeta). I. Larval nuchal organs". Helgoländer Meeresuntersuchungen. 40 (4): 397–417\. Bibcode:1986HM.....40..397S. doi:10.1007/BF01983820.

* v
* t
* e

Cephalopod anatomy

Shell|

| Types|

| External|

* Ammonoid shell
* Argonautid eggcase
* Nautiloid shell
* Orthocone

|

Internal|

* Belemnoid guard
* Cirrate shell
* Cuttlebone
* Gladius (pen)
* Spirula shell
* Stylet

Features|

| External|

* Aperture
* Apex
* Callus
* Lirae
* Periostracum
* Sculpture
* Spire
* Sutures
* Umbilicus

|

Internal|

* Body chamber
* Camerae
* Nacre
* Phragmocone
* Septa
* Siphuncle
* Whorls

Mantle &
funnel|

| External anatomy|

* Dermal structures
* Fins (wings)
* Flotation devices ("secondary fins")
* Funnel–mantle locking apparatus
* Tail

|

Internal anatomy|

* Branchial hearts
* Ctenidia (gills)
* Hepatopancreas (digestive gland)
* Ink sac and ink
* Needham's sac
* Nephridia ("kidneys")
* Nidamental glands
* Osphradium
* Pericardial glands

Head &
limbs|

| Brachial crown|

* Arms
* Hectocotylus
* Tentacles
* Carpus
* Dactylus
* Manus
* Suckers and hooks

|

Buccal region|

* Aptychus
* Beak
* Odontophore
* Radula
* Spadix and antispadix

Occipital region|

* Nuchal crest (occipital crest)
* Nuchal folds (occipital folds)
* Occipital membrane
* Olfactory organ
* Nuchal organ

Other parts|

* Eyes
* Statocysts

General|

* Chromatophores
* Photophores
* Nervous system
* Squid giant axon
* Squid giant synapse

Developmental stages: Spawn → Paralarva (Doratopsis stage) → Juvenile → Subadult → Adult • Egg fossils • Protoconch (embryonic shell)

This annelid-related article is a stub. You can help Wikipedia by expanding it.

|

* v
* t
* e

This animal anatomy–related article is a stub. You can help Wikipedia by expanding it.

|

* v
* t
* e

*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template