Oxford Dictionary definition: mother of pearl from any shelled mollusc.
Our definition: Nacre (pronounced nay-kur) is a substance produced by molluscs (invertebrates with soft bodies, often protected by a shell, such as a clam, oyster or mussel). In the wild the animals produce nacre to coat an irritant, such as a fragment of shell, a scale or a parasite, if it becomes lodged inside their shell. Pearls are formed after thousands of very thin concentric layers of this calcium carbonate substance have been secreted over the irritant.
Natural pearls are very rare, mostly because pearl-producing species of mollusks were nearly hunted to extinction with most natural beds of pearl-bearing oysters depleted by ‘over-harvesting’ (nice euphemism) in the 18th and 19th centuries.
So humans culture them in these animals who, in the wild, have been known to live 25 years. When they’re farmed for pearl culture their life is considerably shorter since pearls can be harvested anything from 6 months to 4 years after the surgical implant of the irritant – horrible for the mollusc as you might imagine and farmers have to watch them carefully and give them special attention during their recovery period which can last from two weeks to three months depending on the species – see here for more details.
“Saltwater oysters are nucleated by opening the shell a mere 2 to 3 centimetres and making a minute incision in the gonad – the oyster’s reproductive organ. The mother of pearl nucleus is inserted into this incision which is then followed with a very small piece of mantle tissue from a donor oyster. The mantle tissue is placed between the mother of pearl bead and the gonad with the side containing epithelial cells facing the nucleus. These epithelial cells are the catalyst of the pearl-sac. The pearl sac grows around the nucleus and begins to deposit nacre. This nacre layering is the beauty of the pearl.
“Saltwater oysters will only produce 1 to 2 pearls per typical nucleation. Akoya oysters can be nucleated with up to 5 beads but the use of only 2 is most common. The Akoya oyster dies at harvest. South Seaoysters (Pinctada margaritifera and Pinctada maxima) accept only one nucleus at a time but, as they do not die at harvest, they may be nucleated several times. If a particular oyster has been successfully nucleated several times and consistently produces fine pearls, the oyster is often returned to the wild to strengthen the genes of future generations of spat.” For more info go to the Raw Pearls website.
According to PETA:
“A pearl is an ulcer that is formed when an irritant, such as a parasite, enters an oyster, who responds by coating it with nacre (a crystalline substance that gives pearls their luster). Stress is what prompts an oyster to secrete nacre (just like stress creates human ulcers).
Because pearls naturally form in only one in 10,000 oysters and because the creation of a pearl can take up to three years, pearl-makers have devised a process called “culturing,” or cultivating, that allows them to exploit oysters faster and cheaper.
Culturing involves surgically opening each oyster shell and inserting an irritant in the oyster. Freshwater pearls are cultured by inserting another oyster’s mantle tissue. Saltwater pearls have beads and another oyster’s mollusk tissue inserted. Fewer than half of the oysters may survive this process.
Cultivators further stress the oysters by suspending them in water in a cage, washing their shells, moving them around in different waters, and raising and lowering their cages to subject them to changing water temperatures.
After the pearls are extracted from the oysters, one-third of oysters are “recycled” and put through the culturing process again. The others are killed and discarded.
For those concerned about the environment, there is another reason to avoid pearls. Aquaculture has contributed to destruction of natural pearl oyster beds from pollution and overharvesting.”
Oxford Dictionary definition: coypu fur
Our definition: Nutria (also called coypu) are large, rodents who are more agile in the water than on land. They live in burrows, or nests, never far from the water. Nutria may inhabit a riverbank or lakeshore, or dwell in the midst of wetlands. They are strong swimmers and can remain submerged for as long as five minutes. Their average lifespan in the wild is eight to ten years. They are varied eaters, most fond of aquatic plants and roots, and are very very cute. Quite beaver-like 😀
Nutria can be rather social animals and sometimes live in large colonies, reproducing prolifically. Females have two or three litters every year, each consisting of five to seven young. These animals mature quickly and remain with their mothers for only a month or two.
Tragically, many misguided humans have cruelly exploited nutria on fur farms (“Originally native to subtropical and temperate South America, it has since been introduced to North America, Europe, Asia, and Africa, primarily by fur ranchers“) and, when these ventures failed and the captive animals escaped or were released into parts of the world where they didn’t belong, they bred fast and caused a lot of damage to wetlands. This has resulted in many attempts to cull them worldwide including, in the US, incentives being paid to people to hunt and trap them. They get $5 per nutria tail handed in to a Coastal Environments Inc. official.