I have H chiragra I suppose and collected them for several years.
I have one Finger length on a large hand and another full hand stretched.
So with that said - I'm off to measure.
The small full shell formed is 11cm long (a bit longer than my finger!).
Fingers are tubes.
The large open fingers, not yet closed into tubes, is 20 cm long.
(smaller than hand)
Most of the shells are in the 20' range maybe some in the 30's .
Measured from under the base while it sat on rule from opposite ends of most
extended finger to most extended. (one curled and the other extended)
I have a number of them out of this display room in my large collection.
When on Kwajalein, I noticed many shells as well as this species drop
their outer
lip and on these 'spiders' fingers and all. Then turn a new main shell
section
that is at or about 180 degrees in rotation and then grow a new lip or
finger set.
Cowries do it that way dissolving, adding rotation and rebuilding.
The shell is very thin on Cowries and this is typically occurs under sand.
After storms, we would have cowries in this 'no outer lip' form with a
chipped thin
turn. These have been observed afterwards with bangs and mends. Suspect
storm damage did it while the shell was hiding itself from fish.
I have some 'helmets' "Giant Horned" that the large lip is obviously off
when
the shell grew another section of the whorl.
I believe that is how the bulk of the shell is enlarged. The snail is
at risk as protection
is taken away. So they hide in sand during the process. They can still
'eat' and
absorb calcium from the rich beds of calcium 'sand'. Stripe, check,
exotic painting to plain
addition is put on by the snail.
Clams add thickness and height/length growing outward.
"Killer Clams" can be small, many in a palm size, to that would enclose
a 3 or 4 year old child. I have my little brother inside the jaws of
one at the airport.
All of these you can see where the shell increased it's size and put in
a pattern, spikes, fingers or some ordainment of some sort.
Most of us put on larger outer clothes as we age... at least in height.
Look at some of the x-ray pictures of Murex and others to see the process.
Martin
On 3/6/2019 12:47 PM, steve rosenthal wrote:
> wasn't there an article with lots of photos about these species in
> American Conchologist about 3-4 yrs ago? If i recall correctly the
> locality figured mightily into it too.
>
>
>
> On 3/6/19, William Bennight <[log in to unmask]> wrote:
>> John, Having both species in my collection I can with reasonable confidence
>> say that the major difference is the size. H. arthritica is a much smaller
>> species. The first time I saw one I thought it was a dwarf or a sex
>> difference of chiragra. I recommend that you get one in each hand and look
>> them both over real good. I would suggest that you attend a COA conference
>> and enjoy the bourse the last two days. The shell dealers there can answer
>> any questions you have.
>> Bill Bennight, past president of the North Carolina Shell Club.
>>
>> Sent from my iPhone
>>
>>> On Mar 5, 2019, at 10:49 PM, John Jacobs <[log in to unmask]>
>>> wrote:
>>>
>>> I'm trying to resolve a mystery regarding two Harpago species, both listed
>>> in WoRMS. H. arthriticus & H. chiragra rugosus. After looking at many
>>> pics under both names, I can't tell them apart. Comments?
>>> Thanks.
>>>
>>> John
>>>
>>> John and Cheryl Jacobs
>>> Seffner, FL
>>> [log in to unmask]
>>>
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