Lecithotropic species are those that emerge from the egg fully formed and do not have a planktonic stage in their growth. This is apparently not a barrier to distribution over the long term, however - the genus Fusinus, for example, is distributed all over the world, with some species spanning over a quarter of the globe. All of them are apparently direct developers, however.

PC.

Paul Callomon
Collections Manager
Malacology, Invertebrate Paleontology and General Invertebrates
Department of Malacology
Academy of Natural Sciences
1900 Parkway, Philadelphia PA 19103-1195, USA
Tel 215-405-5096
Fax 215-299-1170
Secretary, American Malacological Society
On the web at www.malacological.org

>>> Allen Aigen <[log in to unmask]> 10/17/2007 3:54 PM >>>
As Martin noted, rare events, over a long enough period of time, come to be expected events.  Shallow water gastropod species with crawl away larva cannot crawl from island to island in the Caribbean where the water depth separating the islands is too great.  Even lowering the water a few hundred feet due to glaciation would not be sufficient in many cases to allow simple transport.  Although it can be considered to be very improbable for eggs or small specimens to be transported during a hurricane (possibly attached to a vegetation mat), over enough time they will be, and apparently this has happened for many shallow water species.  Could this also have been the deliberate or inadvertant work of people?  In some cases, possibly yes, in other cases they were spread long before people arrived.

Allen Aigen
[log in to unmask]

-- "Martin H. Eastburn" <[log in to unmask]> wrote:
Thinking on this - just a quick note - how about transportation and
range extension:

Egg clusters floating - even those attached - ripped up by a storm.
Then the ocean stream tugs it from the south pacific up the Japanese
current and drops some off here and there.

Typhoons, hurricanes help rip and transport as well.

While on Kwajalein - we had both bird and airplane caught in winds
and came in for landings.
And some of the 'crane' like 'stork' water walking birds might
transport eggs on their feet/legs.   Boats in lakes do that as well.

Naturally is nature way, not man doing it on purpose.

Martin

Pete Krull wrote:
>  The term "range extension" to me means that someone has found a naturally
> occurring, long standing population outside of the area where we already
> knew they lived. The "range" of many species is greater than what we know at
> any point in time only because we haven't discovered the true limits to that
> range.
>
> An "introduction", by definition, is not a range extension. Pete K.
>

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