[Taxacom] Are slugs subgroup(s) of snails

[Stephen Thorpe]

And what about semislugs?! Slugs with visible shells that they can't withdraw into completely! Come on, the whole point with common names is that they are not perfectly precise in meaning - that is why we need scientific names. There is no answer to the question: is a slug also a snail? Actually, this quite nicely illustrates the tendency of certain personality types, common on the list, to try to find perfect  precision where none exists, either in the Code, or in meaning of 'slug'...

And then there is the "pear slug", which is the larva of a sawfly, which isn't a fly but a wasp ...

Take home message: "don't use too many decimal places" ...

Stephen

________________________________________
From: taxacom-bounces at mailman.nhm.ku.edu [taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman [kennethkinman at webtv.net]
Sent: Friday, 4 September 2009 1:29 p.m.
To: taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] Are slugs subgroup(s) of snails

Dear All,
      Francisco wrote that Tandonia are slugs, not snails.  I guess this
depends on how one defines a snail.  If it must have a shell to be a
snail, then I guess this is true.   However, the word snail seems to
originate from the German Schnecke, which can mean either snails sensu
stricto (shelled forms only) or sensu lato (snails and slugs), depending
on the user.
       The specific German word for a slug is Nacktschnecke, literally
meaning "naked snail".  Therefore, this indicates that at least some
Germans must have regarded naked snails (slugs) as a subset of snails.
Maybe this is a good thing, as it would clearly indicate their
relationship, especially to those who might think slugs are some kind of
worm.
     That slugs are a polyphyletic grouping doesn't make me particularly
fond of the term either.  So in that sense it is a bit like the term
"worm" (formerly "Vermes"), and we are now more specific when we refer
to particular types of worms (annelids, platyhelminths, nemertines,
nematodes,  chaetognaths, etc.).  So is the term "slug" (another
polyphyletic group) useful enough to insist that it must be used in
place of the more specific phrase "naked snail" (German
"Nacktschnecke")?  Specifically, was Dan actually wrong in calling
Tandonia "snails".  Again, it seems to depend on the usage (sensu
stricto or sensu lato).
         ---------Cheers,
                        Ken Kinman


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