Slug is a common name for an apparently shell-less terrestrial gastropod mollusk. The word "slug" is also often used as part of the common name of any gastropod mollusc that has no shell, has a very reduced shell, or has only a small internal shell. (This is in contrast to the common name "snail", which is applied to gastropods that have a coiled shell that is large enough that the soft parts of the animal can retract fully into it.)
Slugs exist on land and in the sea, and there is even one genus of freshwater slugs, Acochlidium. The unadorned word "slug" is however applied primarily to land slugs, whereas slugs from the sea or from freshwater are usually referred to as "sea slugs" and "freshwater slugs". Land gastropods with a shell that is not quite vestigial, but is too small to retract into (like many in the family Urocyclidae), are known as semislugs.
The various taxonomic families of slugs form part of several quite different evolutionary lineages which also include snails. Thus, for example, the various families of land slugs are not very closely related to one another, despite a superficial similarity in the overall body form. The shell-less condition has arisen many times independently during the evolutionary past, and thus the category "slug" is emphatically a polyphyletic one.
Slugs, like all other gastropods, undergo torsion (a 180° twisting of the internal organs) during development. Internally, slug anatomy clearly shows the effects of this rotation, but externally the bodies of land slugs appear to be more or less symmetrical, except for the positioning of the pneumostome, which is on one side of the animal, normally the right hand side.
The soft, slimy bodies of slugs are prone to desiccation, so land-living slugs are confined to moist environments and must retreat to damp hiding places when the weather is dry.
The subsequent information in this article applies to land slugs.
Other articles related to "slug, slugs":
... A slug is a counterfeit coin that is used to make illegal purchases from a coin-operated device, such as a vending machine, payphone, parking meter, transit farebox, copy machine, coin laundry, gaming machine, or ... coin, including the weight, size, and shape, a slug is designed to trick the machine into accepting it like a real coin ... Though slug usage is a violation of the law, prosecution for slug usage is rare due to the low value of the theft and the difficulty in identifying the offender ...
... two – the Onchidiacea and Soleolifera – solely comprise slugs ... A third family, the Sigmurethra, contains various clades of snails, semi-slugs (i.e ... shells are too small for them to retract fully into) and slugs ...
... Slug Coronation Street character Portrayed by Marshall Lancaster Introduced by Steve Frost Duration 2006-07, 2009 First appearance 18 December 2006 Last appearance 7 September 2009 Classification Former ... In June 2009 Slug returns, apparently a reformed man ... Slug plants drugs on Becky and she is subsequently arrested ...
... marginata is species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Limacidae ... to predominately carnivorous species like the Spanish slug or the grey slug, L ... marginata eats lichen, algae and mushrooms, and will only eat other dead slugs if no other food is available ...
... Voice Actor Alexander Polinsky Slug is a mutant who lives in the sewers and manipulates people like the Outsiders to commit crimes for him ... Slug was defeated when the Outsiders turned on him, and in the end was electrocuted by Black Lightning ...
Famous quotes containing the word slug:
“Adrift dissolving, bound for death;
Though lumpish thou, a lumbering one
A lumbering lubbard loitering slow,
Impingers rue thee and go down,
Sounding thy precipice below,
Nor stir the slimy slug that sprawls
Along thy dead indifference of walls.”
—Herman Melville (18191891)
“Before me you are a slug in the sun. You are privy to a great becoming and you recognize nothing. You are an ant in the afterbirth. It is in your nature to do one thing correctly: tremble.”
—Michael Mann, U.S. screenwriter. Frances Dollarhyde, aka The Tooth Fairy (Tom Noonan)