Smeagol (gastropod)
Genus of gastropods
From Wikipedia, the free encyclopedia
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 | |
|---|---|
| |
| Smeagol climoi on seaweed buried in gravel, Houghton Bay, Wellington | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Order: | Ellobiida |
| Family: | Ellobiidae |
| 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
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The name of the genus is in honour of Tolkien's fictional character Gollum, who was originally known as Sméagol.[1]
Taxonomy
There are five described species[5] and potentially one undescribed species from Tasmania[6] in the genus Smeagol:[5]
- Smeagol climoi Tillier & Ponder, 1992
- Smeagol hilaris Tillier & Ponder, 1992
- Smeagol manneringi Climo, 1980
- Smeagol parvulus Tillier & Ponder, 1992
- Smeagol phillipensis Tillier & Ponder, 1992
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[clarification needed] → 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]
Distribution
The genus Smeagol is so far restricted to New Zealand and Australia.[1] Smeagol manneringi is known from the south coast of Wellington, and in a possibly genetically distinct form from Kaikōura.[7]
Ecology
These slugs inhabit the upper intertidal zone on gravel substrate.[5]
The development of the veliger is completed in the egg (they do not have a trochophore larval stage).[2]
