Why Do Oysters Make Pearls Here's What You Need To Know

Joan Agie
Feb 29, 2024 By Joan Agie
Originally Published on Oct 14, 2021
Open oyster with white pearl on sand
Age: 3-18
Read time: 7.8 Min

An oyster is a type of mollusk that has a fascinating skill to make Pearls.

Pearls are shiny little stones made for high end jewelry and hold a lot of commercial value among humans. But for oysters, it is a defensive barrier that saves them from a parasite and dust particles.

True to the saying, appearances are deceptive; the oyster is a soft fleshy creature that is covered with the hard shell. A pearl can be produced by a natural process as well as the artificial process. Through the years, humans have also learned to catalyze the process. The produced by human interference is called cultures Pearls. The process of producing pearls artificially is called pearl farming. The pearls produced by oysters on their own are called natural pearls. Around 40 tons (36287.4 kg) of cultured pearls are produced every year. While most of them are put through the same process over and over again to create more peals, unfortunately, farmers kill the oysters and eat them after pearl production. 45 percent of the oysters are killed in the process. An oyster's shell and the pearl are made of the same substance called the nacre. This substance is made up of certain chemicals like aragonite and conchiolin. Generally, the water body plays a vital role in pearl formation. It can be produced in freshwater regions as well as saltwater regions. The chance of finding a pearl in an oyster is one in 10,000. Did you know not all pearls are round in shape some pearls form a different shape? Spherical pearls are the most wanted ones. They are created naturally while the oyster is layering the nacre. Apart from this mollusk, other related bivalves like clams and mussels also produce pearls. The answers to several other questions like will an oyster die when you take the pearl? And does every oyster have a pearl, are given below along with a bunch of interesting facts.

Keep reading and do check out our other related articles on why do fishes die when taken out of the water and how often do you feed a betta fish.

How do oysters make a pearl?

An oyster making a pearl is similar to a spider spinning its web, both of which are done by secretion from glands.

For humans, pearls are valuable objects used in jewelry. But for oysters, they are a form of defense. The shell that looks hard from the outside contains a bivalve that has a soft body. It is used to defend itself from irritants or parasites that enter the oyster shell. Pearls can be made by oysters in freshwater or saltwater sources. Other bivalves such as mollusks, clams, and mussels do produce pearls. They secrete a layer of chemicals like aragonite and conchiolin from an internal organ called the mantle that deposits within the shell. This organ utilizes the nutrients and minerals to secrete these chemicals. The elements produced are called nacre or the mother of pearl which is also a major component to create shells. When an irritant such as grains of sand or pieces of food enters the shell of the creature it triggers the defense mechanism which initiates the secretion of nacre. The nacre layer covers the irritant. Many layers secreted to cover up the nacre eventually hardens and turns into a pearl. It is an immediate reaction to protect itself similar to how you would hurry to wash a speck of dust out of your eye. Nacre that is used to make the shell covers up the irritant or parasite with layers, which eventually turns into an iridescent gem, the pearl. Pearls are not always circular objects. Some of them have slight differences or defects in shape. Such pearls are called baroque pearls. The most frequently observed pearl colors, apart from white, are green, gray, blue, and off white. The pearls created by mollusks and clams also hold a lot of commercial value. One of the best quality pearls called the south sea pearls are produced by the Pinctada maxima or south sea oyster.

What kind of oysters make pearls?

All marine oysters produce pearls. This is just a defense mechanism that is active in all of them. Oysters belonging to the Pinctada genus of the Pteriidae family make the finest pearls. Akoya oysters, producing neutral colored pearls rich in quality are cultured in Japan and China. Pinctada maxima, also known as the white lipped oyster is cultured in Australia, Indonesia, and the Philippines for their large-sized silver, white or golden pearls. Pinctada margaritifera, also called the black lip oyster produces black or white pearls. These are the most sought after pearls in the world.

Pearls are of two types natural and cultured. Natural pearls are the ones produced in the wild without any human interference. Natural pearls are unique but it is hard to harvest them and natural pearls are only produced when an irritant material naturally occurs. This consumes a whole lot of time. Cultured pearls on the other hand are much easier to harvest and can be produced based on our needs. Cultured pearls are produced with the help of pearl framers who make slits on the mantle and insert dust or irritants artificially. Generally, natural pearls and artificial pearls hold the same value. Natural pearls are a bit pricier as they are rare while artificial pearls are comparatively easy to produce and are less rare. Non nacreous pearls cannot be produced artificially as they are made of calcite instead of nacre. In most cases, an oyster after yielding a pearl cannot produce another pearl with the same sheen, hence they are killed. Whether they die after pearl harvesting or not depends on the farmers' method to open the shell. If the oyster shell is pulled apart, then the oyster will definitely die. Insertion of a plug to keep the shell open without completely splitting it will keep the oyster alive.

Oyster on a sandy beach with one large pearl in it.

How cruel are pearls?

It is a topic of debate. The first artificial pearl was harvested by Mikimoto Kōkichi, an American entrepreneur and a Japanese grafting technician in 1893. The pearl farming technique was patented by Mikimoto kokichi and Tatsuhei Mise in 1904.

Many people claim that oysters do not feel pain. The central nervous system responsible for detecting pain is absent in oysters. Oysters are cultivated in baskets or nets that keep them safe from predators. Farms use clean water and regularly change them as it affects the quality of the pearl. They provide a suitable and better environment than the marine regions that are constantly filled with pollutants. However, vegans state that pearls are not cruelty free as the cultivation process includes cutting open their shells and introducing foreign irritants. They say that the oysters suffer a lot when put through the same process repeatedly. For the harvester to take the pearl, a slit is made on the oyster's shell. After harvesting 90 percent of the time they are killed. According to PETA (People for the Ethical Treatment of Animals), the cultivation process puts the bivalve through a great deal of stress. Less than 30 percent of oysters survive this process. Not all pearlers care for the oysters some of them deliberately kill the oysters.

How long do oysters take to make pearls?

Pearls can be formed only by marine pearl oysters. Pearl oysters belong to the genus Pinctada of the Pteriidae family. Pearls last for about 50 years. It takes quite a while to produce jewelry of this quality. The substance used by the oyster to make pearl's, called nacre, also known as the mother of pearl

This nacre layer is said to be the beauty of a pearl. The layering begins when the body naturally tries to flush out the irritant. How long a pearl takes to form depends on the size of the oyster. Small bivalves can produce pearls in six months. Larger oysters can develop a pearl in four years. Generally, the duration varies between the types of pearls. The Pinctada fucata oyster will take 10 - 14 months to form an Akoya pearl, a Tahitian pearl may be formed months. The Pinctada maxima or the white lipped oyster takes two to three years to form a South Sea.

Can pearls change colors? The answer is yes, they can. Your pearl jewelry can change colors as they age. Pearl is made up of an organic substance used to flush a parasite or foreign substance. Since the material is exposed to various conditions the composition changes causing the pearl jewelry to slowly change colors. Sometimes the layers can experience partial disintegration. Cracks or pearls can also be formed. It also needs extra care as it is a fragile body. Farmers take extra care to delay this. The most expensive pearl jewelry is the La Peregrina pearl necklace. It was made by Cartier and sold for $11.8 million in 2011. There is no technique to check if there is a pearl in an oyster. It takes years of expertise and observance to make the right choice. The chance of finding a pearl is also pretty slim. If you are an amateur be prepared for some disappointments.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for why do oysters make pearls then why not take a look at when do catfish spawn, or oyster Facts

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Written by Joan Agie

Bachelor of Science specializing in Human Anatomy

Joan Agie picture

Joan AgieBachelor of Science specializing in Human Anatomy

With 3+ years of research and content writing experience across several niches, especially on education, technology, and business topics. Joan holds a Bachelor’s degree in Human Anatomy from the Federal University of Technology, Akure, Nigeria, and has worked as a researcher and writer for organizations across Nigeria, the US, the UK, and Germany. Joan enjoys meditation, watching movies, and learning new languages in her free time.

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