It is popular that in nature pearls are formed due to the fact that sand enters the body of mollusk. We decided to check if this belief is confirmed by scientific data.

About grains of sand that launch the formation of pearls, write in Scientific and popular literature, on sites Jewelry brands, c services questions and answers, Blogs, online stores and even on portals dedicated aquarium. This image Popular And in the journalistic literature.

Pearls are a biogenic mineraloid, a solid formation of a round or irregular shape, which is created by freshwater and marine bivalve mollusks. Pearl Not counted The mineral, since it contains both an inorganic compound (calcium carbonate, Caco3), and organic (conchiolin). The oldest discovered pearls Relate To the trias and chalk period - their age is from 66 to 251 million years, but they have already lost a characteristic shine called a chandelier. The oldest samples that have retained their brilliance date back to the Eocene period (34–56 million years ago).

Pearls used to be extracted exclusively from wildlife, but at the end of the 19th century Japanese Kokiti Mikimoto Developed And he patented the technology of cultivating pearls, and also created the first pearl farms. In theory, all mollusks, including oysters, mussels and other edible shells, can make pearls, but on the farms for this Use Mostly marine Phylum Mollusca, Pintada Vulgaris and Pintada Margaritifera, as well as freshwater Unio.

The theory that the pearl appears due to the fall of the grain of sand inside the sink, at the end of the XVII century I put forward British biologist Robert Redding. European researchers of the New Age also expressed other hypotheses: some suggested that pearls - a by -product of some kind of mollusks of the disease, others considered it a kind of animal egg, others explained its appearance by the influence of certain special parasites. All these versions were rejected by the middle of the 19th century, when the German researcher Theodor von Hessling and later his colleagues developed and proved the so -called theory of a pearl bag.

The pearl bag is formed in the mantle - the skin fold between the body of the mollusk and the sink. How Explains Professor of the Geology of Basel University Henry Henny, to form this formation, the outer glands of the mantle must enter its inner layer, consisting of connective tissue. As a response, this organ begins to produce calcium carbonate, from which the pearl subsequently develops.

The outer cells of the mantle usually fall into the inner layer due to its damage, and it is not so important what exactly. This can be a consequence of the attack of another animal, and the impact of parasites (for example, multi -shaped worms Polydora Or a sponge of a genus Cliona), But It is unlikely Sanding. Firstly, Henny emphasizes, sandpin itself cannot lead to damage to the mantle. Secondly, mollusks are well able to wash the sand that came between the wings, otherwise pearls would be found in almost every sink. This process was recorded on the video by Douglas Maklorin-Morino, a biochemist and the founder of the Sea of Cortez pearl production company.

Do not use grains of sand growing Pearls on special farms. Their employees use one of two main methods. The first assumes that in the gonads (sex glands) the mollusk-recipient plants a flap of glandular mollusk-donor cells and a blank (a fragment of a freshwater mollusk shell or a plastic blank). Around the blank from this flap, provided by the nutrients of the recipient, and a pearl bag is formed. The second method is the transplantation of the pieces of iron cells of the donor into the mantle of the recipient.

Thus, the theory of the formation of pearls in connection with the granny sink, expressed several centuries ago, is not confirmed by modern research. Both in the wild and on specialized farms, pearls develop in the mantle of mollusks, not because of a foreign body, but due to the mantle of cells of the upper gland layer, which form a pearl bag and later a pearl.

Image on the cover: Image by Dee From Pixabay