Sensory organs of gastropods
The sensory organs of gastropods (snails and slugs) include olfactory organs, eyes, statocysts and mechanoreceptors.[1] Gastropods have no sense of hearing.[1]
Olfactory organs
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In terrestrial gastropods the most important sensory organs are the olfactory organs which are located on the tips of the 4 tentacles.[1] Some terrestrial gastropods can track the odor of food using their tentacles (tropotaxis) and the wind (anemotaxis).[2]
In opisthobranch marine gastropods, the chemosensory organs are two protruding structures on top of the head. These are known as rhinophores. An opisthobranch sea slug Navanax inermis has chemoreceptors on the sides of its mouth to track mucopolysaccharides in the slime trails of prey, and of potential mates.[3]
The freshwater snail Bithynia tentaculata is capable of detecting the presence of molluscivorous (mollusk-eating) leeches through chemoreception, and of closing its operculum to avoid predation.[4]
The deepwater snail Bathynerita naticoidea can detect mussel beds containing the mussel Bathymodiolus childressi, because it is attracted to water that has cues in it from this species of mussel.[5]
Eyes
[edit]In terrestrial pulmonate gastropods, eye spots are present at the tips of the tentacles in the Stylommatophora or at the base of the tentacles in the Basommatophora. These eye spots range from simple ocelli that cannot project an image (simply distinguishing light and dark), to more complex pit and even lens eyes.[6] Vision is not the most important requirement in terrestrial gastropods, because they are mainly nocturnal animals.[1]
Some gastropods, for example the freshwater apple snails (family Ampullariidae)[7] and marine species of genus Strombus[8] can completely regenerate their eyes. The gastropods in both of these families have lens eyes.
Morphological sequence of different types of multicellular eyes exemplified by gastropod eyes:[9]
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Lens eyes
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 1 - anterior chamber, 2 - lens, 3 - retina, 4 - optic nerve. |
 1 - lens 2 - olfactory epithelium 3 - corneal epithelium 4 - corneal endothelium 5 - retina 6 - layer with rod cells 7 - fibrous connective tissue layer 8 - nerve of the eye |
 1 - nerve of an eye 2 - 3 - 4 - eye 5 - tentacle ganglion 6 - epidermis 7 - 8 - nerve of an tentacle 9 - retractor muscle 10 - |
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another drawing of eye of Helix pomatia
Statocysts
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In the statocysts of Haliotis asinina was found the expression of a conserved gene (Pax-258 gene), which is also important for forming structures for balance in eumetazoans.[10]
![[icon]](http://upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/40px-Wiki_letter_w_cropped.svg.png){kind=small} | This section needs expansion. You can help by adding to it. (December 2009) |
Mechanoreceptors
[edit] | This section needs expansion. You can help by adding to it. (December 2009) |
The mechanoreceptors are very crucial to the snail's sensory.
See also
[edit]References
[edit]This article incorporates CC-BY-2.0 text from the reference[9]
- ^ a b c d Chase R.: Sensory Organs and the Nervous System. in Barker G. M. (ed.): The biology of terrestrial molluscs. CABI Publishing, Oxon, UK, 2001, ISBN 0-85199-318-4. 1–146, cited pages: 179–211.
- ^ Davis, Elizabeth C. (2004). "Odour tracking to a food source by the gastropod Meridolum gulosum (Gould, 1864) from New South Wales, Australia (Camaenidae : Eupulmonata : Mollusca)". Molluscan Research. 24 (3): 187–91. doi:10.1071/MR04008.
- ^ Michael D. Miller 1998. Navanax inermis. The Slug Site, accessed 23 March 2009
- ^ Kelly, Paul M.; Cory, Jenny S. (1987). "Operculum closing as a defence against predatory leeches in four British freshwater prosobranch snails". Hydrobiologia. 144 (2): 121–4. doi:10.1007/BF00014525. S2CID 41023961.
- ^ Dattagupta, Sharmishtha; Martin, Jonathan; Liao, Shu-min; Carney, Robert S.; Fisher, Charles R. (2007). "Deep-sea hydrocarbon seep gastropod Bathynerita naticoidea responds to cues from the habitat-providing mussel Bathymodiolus childressi". Marine Ecology. 28 (1): 193–8. Bibcode:2007MarEc..28..193D. doi:10.1111/j.1439-0485.2006.00130.x.
- ^ Götting, Klaus-Jürgen (1994). "Schnecken". In Becker, U.; Ganter, S.; Just, C.; Sauermost, R. (eds.). Lexikon der Biologie. Heidelberg: Spektrum Akademischer Verlag. ISBN 978-3-86025-156-0.[page needed]
- ^ Bever MM, Borgens RB (January 1988). "Eye regeneration in the mystery snail". The Journal of Experimental Zoology. 245 (1): 33–42. doi:10.1002/jez.1402450106. PMID 3351443.
- ^ Hughes HP (August 1976). "Structure and regeneration of the eyes of strombid gastropods". Cell and Tissue Research. 171 (2): 259–71. doi:10.1007/BF00219410. PMID 975213. S2CID 25580163.
- ^ a b Richter S, Loesel R, Purschke G, et al. (2010). "Invertebrate neurophylogeny: suggested terms and definitions for a neuroanatomical glossary". Frontiers in Zoology. 7: 29. doi:10.1186/1742-9994-7-29. PMC 2996375. PMID 21062451.
- ^ O'Brien EK, Degnan BM (2003). "Expression of Pax258 in the gastropod statocyst: insights into the antiquity of metazoan geosensory organs". Evolution & Development. 5 (6): 572–8. doi:10.1046/j.1525-142X.2003.03062.x. PMID 14984039. S2CID 33747158.
Further reading
[edit]- Sergei Tschachotin. 1908. Die Statocyste der Heteropoden. Heidelberg, Univ., Diss., (Zeitschrift f. wissenschaftl. Zoologie; Bd. 90; S. 343–422).
- Susswein, Abraham J.; Cappell, Mitchell S.; Bennett, Michael V. L. (1982). "Distance chemoreception in Navanax inermis". Marine Behaviour and Physiology. 8 (3): 231–41. doi:10.1080/10236248209387020.
External links
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