Subject: | |
From: | |
Reply To: | |
Date: | Sun, 2 Jun 2002 14:24:39 +1200 |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
> > On a shell-related note, does anyone know if the range of Provocator
>> pulcher Watson has been enlarged from the tiny domain around the
>> Kerguelen/Heard Island area shown in Poppe & Goto? Also, why is it that
>> so many volutes have such limited ranges? - their larval stages must not
>> travel all that far before settling, i am guessing - but are there other
>> contributing factors?
>
>I don't think anyone with more experience than I has answered this yet,
>so...
>
>The large protoconch of most volutes is a clue that they do not have a
>veliger stage but crawl directly from the egg, thereby limiting the range.
>
>Didn't I read something some time back about a Cymbium species that was
>observed disgorging live young direct from the mother (I think she was
>brooding the eggs). If so, I'd like the reference to review it.
I have collected Provocator mirabilis eggcapsules. These had living
juvenile shells within, about 3mm long, one per capsule. They crawl
away; no free-living veliger stage at all, and I think this is the
case with most volutids, certainly those with large protoconchs.
Provovcator spp will be limited to the shelf and upper bathyal, and
so in theory unable to cross abyssal barriers. I guess this is why P.
mirabilis is restricted to the NZ continental area (which is MUCH
larger that the currently-exposed land area).
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
<[log in to unmask]>
Seashell, Macintosh, VW/Toyota van nut
|
|
|