Sensory organs of gastropods explained

The sensory organs of gastropods (snails and slugs) include olfactory organs, eyes, statocysts and mechanoreceptors. Gastropods have no sense of hearing.^[1]

Olfactory organs

See main article: rhinophore.

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

See also: Evolution of the eye. 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]

Lens eyes

another drawing of eye of Helix pomatia

Statocysts

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]

Mechanoreceptors

See main article: Mechanoreceptor. The mechanoreceptors are very crucial to the snail's sensory.

See also

• Hancock's organ
• Sensory ecology
• Sensory systems in fish

References

This article incorporates CC-BY-2.0 text from the reference^[9]

Further reading

• 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 . 10.1080/10236248209387020.

Notes and References

1. Chase R.: Sensory Organs and the Nervous System. in Barker G. M. (ed.): The biology of terrestrial molluscs. CABI Publishing, Oxon, UK, 2001, . 1–146, cited pages: 179–211.
2. 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 . 10.1071/MR04008. free .
3. Michael D. Miller 1998. Navanax inermis. The Slug Site, accessed 23 March 2009
4. 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 . 10.1007/BF00014525. 41023961 .
5. 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 . 10.1111/j.1439-0485.2006.00130.x. 2007MarEc..28..193D . free .
6. Book: Götting, Klaus-Jürgen . Lexikon der Biologie . Schnecken . Becker, U. . Ganter, S. . Just, C. . Sauermost, R. . 1994 . Spektrum Akademischer Verlag . Heidelberg . 978-3-86025-156-0.
7. Bever MM, Borgens RB . Eye regeneration in the mystery snail . The Journal of Experimental Zoology . 245 . 1 . 33–42 . January 1988 . 3351443 . 10.1002/jez.1402450106.
8. Hughes HP . Structure and regeneration of the eyes of strombid gastropods . Cell and Tissue Research . 171 . 2 . 259–71 . August 1976 . 975213 . 10.1007/BF00219410. 25580163 .
9. Richter S, Loesel R, Purschke G, etal . Invertebrate neurophylogeny: suggested terms and definitions for a neuroanatomical glossary . Frontiers in Zoology . 7 . 29 . 2010 . 21062451 . 2996375 . 10.1186/1742-9994-7-29 . free .
10. O'Brien EK, Degnan BM . Expression of Pax258 in the gastropod statocyst: insights into the antiquity of metazoan geosensory organs . Evolution & Development . 5 . 6 . 572–8 . 2003 . 14984039 . 10.1046/j.1525-142X.2003.03062.x. 33747158 .