Scientists Debunk Myth that Pearls come from "Grains of Sand"

Caitlin

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Scientists Prove that Pearls Can't Come from a Grain of Sand.

The Most Renowned of all Pearl Myths- that pearls come from grains of sand -has been disproven in a scientific experiment.

Internationally renowned Marine Biologist and Pearl farmer, Douglas McLaurin, M.Sc. Aquaculture, and partners in a scientifically run pearl farm, in Guaymas, Sonora, Mexico, have produced a video of a scientific experiment of inducing a natural pearl to form from grains of sand.

These posts were in another thread, but deserve a thread of their own. I hope people will use this thread to inform well-meaning but incorrect pearl experts and the myth-believing public that pearls are not caused by grains of sand.
 
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Whoa! Just noticed this thread today...never had a chance to talk about our experiences with our bivalves here in the Sea of Cortez, so let me share a bit :)

One of the first experiments we tried (back in the early 1990's) was to use sand to grow pearls...if one grain of sand works: a million grains of sand will work a million times better!!! Logical. But we were never able to coax the oysters to produce pearls, they woul all clean their insides by first secreting mucus (lots of it), the mucus would serve to attach the sand and then...it would be set free.
After years of explaining this -over & over- I decided to shoot a video and post this information on our Blog...so, on this entry you can actually see what happens to sand inside an oyster.

On this video you can see what happens when you add sand to an oyster:
http://www.youtube.com/watch?v=9BF5ByLETYo

Sorry to say it as well... sand does not result in natural pearls, just as storks don't bring babies from Paris...
 
And then the question is raised: What causes natural pearls to form??? From my perspective: parasites. We ALMOST always find evidence of parasitic infestation on the oyster's shell. This was also the subject of one of my Blog posts "Speaking of Natural Pearls Pt. 2".

Finally, we made an "instant video" some years ago...but have never gotten around to translating it into English (done in Spanish), but you can see the images of natural pearls and how these coincide with blisters on the shell...if you care to watch the video here it is:


By the way...I have some splendid natural blister pearl specimens on Pteria sterna oysters (a.k.a: "Rainbow Lipped Oyster"), if anybody is interested in photos please let me know.

Have fun!
 
I would love to see them and I'm sure that others would as well.
 
Great video Doug! The loose pearls appear to have formed around broken pieces of shell nacre in the space?


I sure enjoy looking at your oysters.
 
Great video Doug! The loose pearls appear to have formed around broken pieces of shell nacre in the space?

Not really Dave! Further inspection proves that drill-worms are responsible for a large proportion of these pearls.

Will post some natural blister pearl photos for you Nora :)

In the meantime...enjoy these 2 fine specimens!

Collage-Blister-Pearls.jpg
 
Will post some natural blister pearl photos for you Nora :)

Not the best picture, but here's a little blister, with no evidence of parasite outside the shell. This mantle yielded 5 other loose pearls of similar or larger size and proximity. This one likely popped out of the sac into the extrapallial space and was nacred to the wall.
 

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Not the best picture, but here's a little blister, with no evidence of parasite outside the shell. This mantle yielded 5 other loose pearls of similar or larger size and proximity. This one likely popped out of the sac into the extrapallial space and was nacred to the wall.

I've seen similar natural blisters on freshwater mussels and also without evidence of a parasite in the shell. But in our pearl oysters those are rare...the common thing is to find drill worms or mussels. On these photos you'll see 3 different blisters, all with evidence of the drill-worm (I have not removed them) on the back side (but the photos do not come out...sorry!). On one of the photos you'll see that the worm was able of drilling a hole thru the nacre...very evident.

Natural Blisters 016 [640x480].jpgNatural Blisters 018 [640x480].jpgNatural Blisters 017 [640x480].jpgNatural Blisters 019 [640x480].jpg
 
On one of the photos you'll see that the worm was able of drilling a hole thru the nacre...very evident.

View attachment 12627

Excellent example Doug. Breaking through the shell can lead to other results. Floating pieces of nacre, perforations, cuticles as nuclei etc.

Even these photos indicate onset at a periostracial level. It stands to reason, the higher incidence of pearl formations occurs there, afterall the shell is weakest and has significant soft tissue attachment.

Although single causes can be identified, many natural pearls are the result of multiple etiological factors.
 
I agree Dave...there are many different causes. Some may be more common to certain species in certain geographical locations or under certain weather conditions. Life is perplexingly complex, yet is seems straightforward at times.

But let us all repeat this mantra:

"There is no grain of sand in the pearl...
there is no grain of sand in the pearl..."
(while clicking your surf sandals together...if that can be possible)
 
I am wondering whether nacre secretion is induced following an immune response? This might explain why sand is not efficient as it would not trigger a response? Is there any evidence for a (primitive) immune system in oysters? Then you could coat your nuclei with antigen from different species, he, he.
 
Never sand Caitlin. Never. And we have even gone as far as using electrical shocks on the mantle or the use of jellyfish stingers to induce natural pearls... of course, the reason to do this was to gain KNOWLEDGE and not to produce FAKE NATURALS (it would take many years to obtain good sized naturals, so there is no sense in doing it).
I believe that the agent in charge of producing pearls cannot be a "one-night-stand" (to say it in a colloquial way) it has got to be something that will be there, nagging you all the time, for weeks or even longer (think of a teenager complaining or making noises all the time)...then the pearl oyster must RESPOND. The only things I envision doing such active task are these worms and other parasites...and perhaps most politicians (would this be considered redundant?).

Sorry...couldn't avoid it...was compulsory (me and my BIG keyboard!!!) LOL
 
I thought I'd add Buck Nacre's immortal words to this thread:

Not Irritating


Submitted by Buck Nacre

Way back when, someone whose identity is lost to pearling history declared that a natural pearl forms when foreign matter invades a shelled mollusk’s soft tissue, and the mollusk progressively coats the invader with shell material to sooth the irritation it causes. That explanation has been repeated so often, it’s taken as true. But both common sense and close analysis demonstrate it’s false.

First, common sense: If soothing irritation were the mollusk’s purpose in coating the foreign matter with shell material, why would it continue coating once enough layers were applied to give the irritant a smooth surface?

Second, close analysis: Foreign matter gets inside the mollusk and either lodges in the mantle tissue where the epithelial cells that produce shell material are, or it picks up epithelial cells on its way to settling somewhere else in the mollusk’s soft body. Whether in the mantle or elsewhere, the epithelial cells continue doing what they’re genetically programmed to do -- produce shell material. But rather than continuing to build a shell, the cells form a pearl sac and create a pearl that encapsulates the invader. A cultured pearl with a bead as its core is produced by adapting this process.

For more detail, see “Pearl Production” by Joseph Taylor and Elisabeth Strack in The Pearl Oyster, edited by Paul Southgate and John Lucas, and published by Elsevier.

So far, we have
Douglas McLaurin
Buck Nacre
Jeremy P Shepherd
The Pearl Professor
heading up the list of naysayers to the grain of sand theory. Sorry two of them are anonymous, but I'll take support where ever I can get it.
 
Than you Caitlin, oh esteemed leader of the Miss Marple brigade! and Douglas for all your time, efforts and sharing the results! I re-posted the link to the youtube video to FB I know others who will be interested in this.

Cheers!

Ash
 
I don't consider myself to be the last word or anything close. But, being Biologists we have always wondered at Life's amazing strategies, patterns, shapes, etc. Life is simply MAGNIFICENT. But we are also Engineers and we wonder and tinker: how does the animal do that? Can we fool it? Can we make it do our will?

Your knowledge is incomplete unless you actually try things out yourself, and the Scientific Method is great because you observe, try to replicate, obtain results...and you do it again and again until you obtain true knowledge, or you don't get anything (might happen).
In this sense, these pearly-myths are like a form of religion: someone stated something (like the "grain of sand" myth) and it is taken like church-creed or dogma and everyone just turns it into a belief and a ritual, when it was just "an uninformed guess". At least, that is what I believe might have happened.

I don't consider actual "Pearl Authorities" to be wrong, but our information is based on our hands-on knowledge of these creatures.
 
In this sense, these pearly-myths are like a form of religion: someone stated something (like the "grain of sand" myth) and it is taken like church-creed or dogma and everyone just turns it into a belief and a ritual, when it was just "an uninformed guess". At least, that is what I believe might have happened.
And it seems that person was K. Mikimoto, a bit careless in his desire to produce a popular book on the subject, perhaps.
 
It is time to debunk Mikimoto's position on that, regardless of the respect he deserves for his high quality cultured pearls.He had no idea that repeating something he heard would set off a world wide myth! And not the myth he wanted to "cultivate", either!
 
...our information is based on our hands-on knowledge of these creatures.

Well said Doug. There is no substitute for working field experience.

However, I have found multiple examples of sand concreted in repaired shells. It stands to reason, when shells are damaged, there is an uptake of sand, shell and seawater into the extrapallial space.

Perforation of the pallial mantle is the key phrase, not irritation.

Shell growth, repairs and pearls are mantle functions at a pallial level, where cells thrive, multiply and divide. Sand is inert and does little to cause cellular "irritation" as the myth suggests. Even bits of shell or highly polished shell bead nuclei are inert, without an additional factor (ie) graft tissue or parasite.

The word irritation, is itself irritating. To me irritation suggests infection, inflamation, and nerve involvement. In pearl culture, success and survival can be increased by reducing these effects on the animal.

I really doubt Mikimoto coined this myth, but he certainly did well to perpetuate it. I think it was convenient to be misleading.
 
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