Smeagol (gastropod)
Smeagol is a genus of small air-breathing[2] sea slugs of the upper intertidal zone.[3] They are pulmonate gastropod mollusks related to land slugs and snails.
Smeagol | |
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A photo of Smeagol species | |
Scientific classification | |
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Family: | Ellobiidae Pfeiffer, 1854 |
Genus: | Smeagol Climo, 1980[1] |
Diversity | |
5 or 6 species |
Analysis of DNA sequences has shown that Smeagol belongs in the family Ellobiidae, and is therefore closely related to ellobiid snails.[4]
Etymology
The name of the genus is in honour of Tolkien's fictional character Gollum, who was originally known as Sméagol.[1]
Species
There are five described species[5] and potentially one undescribed species from Tasmania[6] in the genus Smeagol:
Anatomy
Smeagol manneringi has no tentacles and is a very active blind animal with a size of up to 10 mm.[1]
Smeagol species have no shell. They have a weakly developed snout.[2] The radula is unicuspid[1] and the radular dentition is of the rhipidoglossate type.[2] They have a radular membrane of flexoglossate type.[2] They have no jaw.[1][2] They have salivary glands with salivary ducts.[2]
The excretory organs are only the left ones, in the pallial cavity.[2] In the circulatory system the haemolymph circulates as follows: mantle → nephridium or nephridia → heart.[2]
These slugs breathe using a pallial lung.[1] They have a contractile pneumostome.[2]
They have a suprapedal gland.[2]
The number of chromosomes is unknown.[2] They have no sex chromosomes.[2]
Ecology
These slugs inhabit the upper intertidal zone on gravel substrate in New Zealand and Australia.[1][5]
The development of the veliger is completed in the egg (they do not have a trochophore larval stage).[2]
References
- Climo F. M. (1980). "Smeagolida, a new order of gymnomorph mollusc from New Zealand based on a new genus and species". New Zealand Journal of Zoology 7: 513-522. Full text on books.google.com
- Barker G. M. (2001) Gastropods on Land: Phylogeny, Diversity and Adaptive Morphology. 1-146. In: Barker G. M. (ed.) (2001) The biology of terrestrial molluscs. CABI Publishing, Oxon, UK, cited pages: 52, 127-134. ISBN 0-85199-318-4.
- Marshall, B.; Rosenberg, G. (2016). Smeagol Climo, 1980. In: MolluscaBase (2017). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=551549 on 2017-09-13
- Dayrat, Benoît; Conrad, Michele; Balayan, Shaina; White, Tracy R.; Albrecht, Christian; Golding, Rosemary; Gomes, Suzete R.; Harasewych, M.G.; Martins, António Manuel de Frias (2011). "Phylogenetic relationships and evolution of pulmonate gastropods (Mollusca): New insights from increased taxon sampling". Molecular Phylogenetics and Evolution. 59 (2): 425–437. doi:10.1016/j.ympev.2011.02.014. PMID 21352933.
- Tillier S. & Ponder, W. F. (1992). "New species of Smeagol from Australia and New Zealand, with discussion of the affinities of the genus (Gastropoda: Pulmonata)". Journal of Molluscan Studies 58(2): 135—155. doi:10.1093/mollus/58.2.135
- West R. (February 2009). Proposed determination Smeagol hilaris, a marine slug, as a critically endangered species. Fisheries Scientific Committee, Ref. No. PD43, File No. FSC 09/01, 3 pp., PDF.
Further reading
- Haszprunar G. & Huber G. (1990). "On the central nervous system of Smeagolidae and Rhodopidae, two families questionably allied with the Gymnomorpha (Gastropoda: Euthyneura)". Journal of Zoology 220: 185–199. doi:10.1111/j.1469-7998.1990.tb04302.x
- Romero, P. E., Pfenninger, M., Kano, Y. & Klussmann-Kolb, A. (2016). Molecular phylogeny of the Ellobiidae (Gastropoda: Panpulmonata) supports independent terrestrial invasions. Molecular Phylogenetics and Evolution 97: 43-54
External links
Wikimedia Commons has media related to Smeagolidae. |
- Smeagol discussed on RNZ Critter of the Week, 17 September 2015
Wikispecies has information related to Smeagolidae |