Dear Marlo,

Submersion may certainly be a good strategy to improve cold tolerance
for mollusks at latitudes like that of northeast Florida.

Harry


At 08:29 PM 3/25/2007, you wrote:
>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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