I have to take another look, but I believe they stated that
delessertiana tends to favor sheltered inshore (bay) habitats, while
duplicatus was more typical of the open coast/offshore type habitats.
In a couple of prior  trips to Brazoria County, dating to when the
species had been "split",  I don't remember seeing many if any
delessertiana  on the beach, but they were the only ones I found in
places like Christmas Bay.

On 3/3/15, Leslie Crnkovic <[log in to unmask]> wrote:
> Steve,
>
> I've seen that a couple times with the crabs, especially with Moon Snails.
>
> Did Hülsken et al. place one species as a bay dweller and the other as
> offshore?
>
> Les
>
>
> -----Original Message-----
> From: Conchologists List [mailto:[log in to unmask]] On Behalf Of
> Steve Rosenthal
> Sent: Monday, March 02, 2015 8:49 PM
> To: [log in to unmask]
> Subject: [CONCH-L] Double Occupancy moon snails
>
> Over the past few days I witnessed a very  large number of egg collars from
> moon snails (Neverita spp.)  on Quintana Beach in Brazoria County, N. Texas.
> On the first couple of days there were a lot of live individuals uncovered
> at low tide, and at high tide in rough surf   there were a lot of fresh dead
> moribund specimens, of which I collected a fair number. On cleaning these
> out, I noticed I had two crabbed specimens, however after the crabs came
> out, so did a dead moon snail, still with the operculum. I guess once the
> animal dies and begins to rot or recede into the shell, there is enough
> space for the crab to move in.
>
> Also of note, using a sample of about 50 shells encountered , the ratio of
> duplicata  to  delessertiana was about 1.3 to 1,  which I think is  a more
> even mix of the two species than I recall being cited in the literature for
> the open ocean (beach) habitat? i.e.
>
> Hülsken T., M. Clemmensen & M. Hollmann (2006) Neverita delessertiana
> (Récluz in Chenu, 1843): a naticid species (Gastropoda: Caenogastropoda)
> distinct from Neverita duplicata (Say, 1822) based on molecular data,
> morphological characters, and geographical distribution. Zootaxa 1257:
> 1–25., available online at
> http://www.mapress.com/zootaxa/2006f/zt01257p025.pdf
>
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