Harry,

Your "cold-tolerant and can better survive the winters" hypothesis is
plausible, but may be misapplied.  It may not be that N. fulgurans is more
cold-tolerant as much as that the other three are not.  My reasoning - the
habitat for N. fulgurans is below the mean tide line whereas the other three
reside exposed above the mean tide line.  And, during the winter months
Florida's east coast experiences few and only shallow minus tides.
Therefore, N. fulgurans spends the winter "under water" where it is
insulated from the cold temperatures of winter.  As a Florida winter surfer
who often waits for the next set of waves in the water to keep warm, I can
appreciate N. fulguran's cozy, under water winter home.
Marlo
merritt island, fl

From: Conchologists List [mailto:[log in to unmask]] On Behalf Of
Harry G. Lee
Sent: Saturday, February 24, 2007 3:46 PM
I feel I owe you a summary and analysis of all the discussion which took
place in our forum from 12/27/06 to 1/23/07 under the threads: "Western
Atlantic Nerita, west Florida nerites, etc.

With the most extensive contemporary range in east Florida, west Florida,
the western Gulf of Mexico, and South America, there is little room for
argumant that Nerita fulgurans is the vagabond of this group. It looks like
N. tessellata and N. versicolor are in a near dead heat for second in this
nomadic ranking, and N. peloronta, the Bleeding Tooth, is a tropical
stay-at-home by comparison.

Yet there are vexatious facts that won't exactly go away: In west Florida,
what about the record of N. tessellata from Longboat Key, Sarasota C. FL
etc.? "Rocks at the channel side" sounds like a real habitat, and likely
this was a living community - especially when one considers the other
records for that species in the vicinity. The same puzzling situation occurs
with the historical records of N. peloronta and N. versicolor in St.
Augustine on the east Florida coast in the 1880s and 1919, when C. W.
Johnson, a meticulous field and museum malacologist found them living? We
can be reasonably ceertain that these species are absent from that area as
members of the Jax Shell Club and others have only found N. fuklgurans in
suitable habitat there since the 1940's.

Given this assortment of data, I'll offer two plausible hypotheses for your
consideration:

(1) Nerita fulgurans is more cold-tolerant and can better survive the
winters. (Don't ask me about the dynamics in South America).
(2) A metropolis of these four species exists in southeast Florida and
spawns regularly. It broadcasts veligers (not much information on larval
longevity; a ten-days swin for one Australian species) which ride the
Florida Current and the Gulf countercurrent to points north. The trip is
tenuous, and survival is rare, but when conditions are suitable, settling
occurs, and juveniles develop. Cold weather almost always puts and end to
such settlements, but in exceptional instances a colony may overwinter, the
snails grow to adulthood, and a few lifecycles may pass in situ. Not long
afterward, however, a normal cold winter extirpates these pioneers. Thus the
occasional appearance of N. versicolor and N. peleronta in St. Augustine and
of N. tessellata in Sarasota.

Harry

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