How pearls are formed and why climate change is a threat
There is no doubt that the pearls they are wonderful, but few people really know the secrets of their training. Who produces them? How? Under what conditions? Science has understood in detail how Nature produces them and, in the process, has discovered that studying them can lead to strategies for preserving those who create them: clams.
Pearls are organic gems
When it comes to gems, we usually think of precious stones and diamonds, many of which are formed in the bowels of our planet. Exposure to high pressures and temperatures for millions of years gives rise to products of high commercial value.
The history of pearl formation is different. Instead of from the bowels of the Earth, these are formed in the entrails of molluscs, which is why they are considered organic gems. “‘Pearl’ is a word we use for a brilliant creation that produces a shellfish,” as defined by Gabriela Farfan, environmental mineralogist and curator of gems and minerals for Coralyn W. Whitney at the Smithsonian National Museum of Natural History.
Technically, all mollusks can produce pearls
In general, all mollusks can produce pearls, that is oysters, mussels and clams. However, commercially, only a few saltwater clams and freshwater mussels are harvested for cultivation for later use as buds.
But why do they create them? Practically everything that exists on Earth appears to perform a function or be the result of the execution of a function, and even more so if it is produced by biological entities such as animals. Pearls are no exception.
THE mollusks produce pearls as a protective mechanism against substances that seep through their soft tissues. “If the debris gets stuck in a mollusk and cannot expel it, they cover it with their own mother of pearl or seashell“, Farfan explained. To do this, they use a material known as mother of pearl, also responsible for giving these gems their opalescent luster.
The role of mother of pearl in the formation of pearls
Mother of pearl is a type of bark that gives pearls a pearly appearance that is very attractive to humans. But beyond its visual value, this substance is special because it also provides a lot of resistance. This material is made up of organic secretions with a carbon-based mineral known as aragonite, which is responsible for its strength.
Mollusks exude layer after layer of shell material, as if they are building something, around an intruder in their soft tissues, which can be a grain of sand or a parasite.
Pearl farms produce symmetrical gems in no time
We could compare this process with the brick and concrete laying that is usually done in a building. Of course, as with geological gems, pearl formation also takes a long time, but humans have learned to manipulate the process to obtain them more quickly.
Thanks to this there are pearl farms which produce slightly different gems, smoother and more spherical than those produced in a more natural way. To achieve this, pearl growers carefully insert a small shell pearl into the shellfish as a raw material. Then, they take it to the ocean or lake to take care of producing it. The pearl formation process takes two to five years.
With a so efficient and economical process, one would expect farm-grown pearls to be easier to source than their natural counterparts. But that doesn’t mean they stop being special or precious. On the contrary, in these cases, the value is given by the particular symmetry and brilliance that this process gives them.
Climate change could endanger the life of shellfish and pearl production
But not everything is as good as it seems. The climate change, through the increase in the temperature of the oceans, it is affecting numerous species, including the molluscs responsible for the formation of pearls. And, just like us, shellfish have optimal temperature ranges and other conditions in which their bodily functions develop best. It is likely that the global warming alter these intervals, leading to changes in the way they use their energy.
For example, the shells of saltwater molluscs can weaken as the oceans acidify. There is a risk that they may need more resources, such as the mother of pearl they use to make pearls, to repair their shells and to survive. For this reason, scientists have also focused their attention on pearlescent gems and the molluscs that produce them as research. Understanding pearl formation in more detail could shed light on how mollusks will respond to impending environmental fluctuations.