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Limax maximus, an air-breathing land slug, ?+ t/ O" X- y1 @, M
Slug is a common non-scientific word which is most often applied to any gastropod mollusk whatsoever that has a very reduced shell, a small internal shell, or no shell at all. Gastropods with a coiled shell that is big enough to retract into are called snails.
- a' D6 p* y4 i6 s9 y1 dA slug-like body is an adaptation which has occurred many times in various groups of snails, both marine and terrestrial, but the common name "slug" is most frequently encountered as applied to air-breathing land species, including a few agricultural and horticultural pest species. This article is primarily about air-breathing (pulmonate)
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& \( o! E3 x/ g5 z1 xLand slugs, like all other gastropods, undergo torsion (a 180º twisting of the internal organs) during development. Internally the anatomy of a slug clearly shows the effects of this rotation, but externally the bodies of slugs appear rather symmetrical, except for the positioning of the pneumostome, which is on one side of the animal, normally the right hand side.
% O& c1 w& q: i1 y- pThe soft, slimy bodies of slugs are prone to desiccation, so land-living slugs are confined to moist environments.# C. U5 B! f0 s: f
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Banana slug, Ariolimax columbianus, Univ. of Calif. Santa Cruz% D0 x5 m" N# Z, {; B& w( d
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Mating Great Grey Slug found in Maryland, USA |
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楼主: surge
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发表于 10.7.2008 21:55:45
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