Pearls are objects produced by mollusks, animals who protect their soft bodies with hard exterior shells like oysters and mussels. Mollusks live in nearly all continents on Earth, but pearls from Polynesia are particularly special and treasured in the world of jewelry. So, what’s special about them? 

To begin, pearls are defense mechanisms that protect the mollusk from parasites or dirt that enter the shell and touch the soft muscle. Mollusks deal with intruders though isolating them with a pearl sac that secretes nacre, also known as mother of pearl. Over time, enough nacre is produced to trap the intruder in a thick, shiny ball we know as pearls.  

The most famous and common pearls are found in Asia and Oceania, specifically freshwater, creamy white pearls from China and Japan which are more abundant compared to saltwater pearls since multiple pearls can grow in one freshwater mollusk. In general, freshwater mollusks are more resilient than those that live in saltwater since rivers experience harsher changes in shorter amounts of time, which can push more irritants into the mollusk. In the wild, pearls are very rare–mollusks’ shells are very strong and typically impenetrable so humans must farm them by manually putting a bead into the mollusk to trigger this defence mechanism. 

Along with cream coloured pearls, the shine can come in different shades of pink, gold, and even green. The black-lipped pearl oyster produces dark black and bronze pearls, often coming with hues of purple and blue. These oysters live in the salty waters of Polynesia, and it takes approximately four years to grow an adequate sized pearl. These are Tahitian pearls, named the queen of pearls in 1994.

Tahitian pearls aren’t even considered the most exclusive even though one can cost up to $30,000. In the South Sea lives the sensitive gold-lipped pearl oyster who grows the 12 inch South Sea pearl, a creation that can sell for $100,000. 

Humans have been collecting mollusks for millennia for food and aesthetic purposes, and were used as a form of currency several centuries ago all over the world. Surprisingly, they are related to octopuses and a single oyster can filter up to 40 gallons of water in a day. Mollusks are essential to marine ecosystems, and there is so much more to them than their pearls–it’s not only what’s on the inside that counts!

Test your knowledge:

1. Which mollusk grows faster, saltwater or freshwater? Why?

2. What do pearl sacs secrete that builds and forms the pearl?

3. Do pearls form as a way to store excess food or do they form to encase irritants?

I’m sure you did pearl-fectly! ;)

-Val