Just to be snarky ; Are you sure you have them right side out?
---- Ellen Bulger <[log in to unmask]> wrote:
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(Ramble ahead. Skip if you require brevity!)
Howdy Shell Folk,
I now know the orientation of the opercula of *Xenophora conchyliophora.*
I do not know the preferred morphological terminology for the structures of
said opercula. The only mention I find in Kreipl & Alf is a general for all
of the Xenophoridae and reads as follows:
"Operculum horny, yellowish to brown, nucleus lateral, with simple growth
lamellae, sometimes with conspicuous radial striae or hollow radial ribs
(in one species stromboid with mid-lateral nucleus and with sharply
serrated edges)."
Great. Swell. Would it have been hard to name that species? Eh? Whatever.
No pictures, no photos, no drawings. Not a lot of species. Would not be
hard to include photos next time.
So one species has a stromboid 'perc. I don't know if I would describe *X.
conchyliophora*'s operculum as being stromboid. I assume stromboid in this
context means a bit pointy with a rib that serves to reinforce the
structure. I've seen Xenos lumping along like conchs. It certainly looks
like they jam their 'percs into the sand just ahead of themselves and then,
um, reel in their foot. Thomp, thomp, thomp!
I suspected that the ever-so slight reinforcing rib was pointed down into
the sand. (Truly it's really more a hint of a rib. Like a drawing of a rib,
something that says, if you should have a rib, it would go HERE)
As I am pulling specimens out of the freezer, I see that the "rib" does
point DOWN. (Okay, okay, it has a ventral orientation. Happy now? I'll be
glad to use the appropriately flowery vocabulary as soon as I'm up to speed
on it.) These specimens were frozen when the snail was retracted into the
shell. I can't write off the possibility that they twist their feet when
they are walking/jumping/polevaulting or whatever you call that lurching
mode of locomotion. Lurching. They lurch. I like that. Good for Halloween
time too.
The tide was a bit high when I collected these specimens. I can't rightly
see what goes on under the shell in five feet of water, especially as I
don't wear lead. Next live one in the shallows I see, I will be watching
that movement like a hawk.
It's not much of a reinforcement. The 'percs aren't very big or strong. If
a Xenophora were to crawl into the undersea equivalent of REI (There's an
animated film pitch for a VERY niche market, eh? FINDING NEMO as sponsored
by Patagonia.) the hipster outdoor athlete clerk (Probably a ceph,
chromatophores presenting a classic plaid pattern. Crypsis being context
dependent.) would roll its eyes at the flimsy little 'perc.
Or maybe not. Backpackers like lightweight sturdy equipment and Xenophora
are surely the backpackers of the gastropod world. They like techy gear
with the latest materials. By comparison the conchs are rolling around in
Winnebagos. Xenophora opercula are STATE OF THE ART!
Long story short? The rib thing that is just barely there, that thing goes
on pointing DOWN.
Ellen
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