Pearls in the Web of Life – Part 3
In our last entry, where we learned that the outside of pearl oysters acts as a small ecosystem in itself, but now we will “dive deeper” into the oysters themselves to find that this pattern repeats itself -in a kind of Hermetic understanding of the “As is Above, is Below” law- but with different actors involved. And, if you ever had the opportunity to stare into a live and open pearl oyster, you would begin experiencing a calmness that emanates from these animals…as if staring into an encased, fleshy orchid, a peaceful womb. And it is this protective environment that some unusual creatures are searching for.
Many pearl oysters received the name of “Mother of Pearl Oysters” since they would “give birth” to pearls themselves, but many small and frail creatures would probably pronounce this same name to describe these mollusks just as many people call our planet “Mother Earth”. Who are the dwellers of this small, motherly environment? Well, there are just a few and each variety of pearl oyster will be able to house its own unique species in a unique biological association known as commensalism: species that live on another one, without causing damage to their host.
One of the most bizarre of these is the “Pearl Fish” (Carapus), serpentine-shaped and almost translucent fishes that love living inside pearl oysters of genus Pinctada. These slow and frail creatures require a place to hide from predators, and pearl oysters offer them quite a large and luxurious nacreous apartment. Little is known of these reclusive fishes, which are easily identified due to their unusual dwelling habits, including starfishes, other bivalves and -quite oddly- inside the anus of sea cucumbers. It is easy to imagine why they would prefer pearl oysters, isn’t it?
Well, these fishes will ultimately find an oyster, find a mate, produce their offspring and live their “pearl dream”, but it happens that they also end up dying and their tiny corpses will soon start decaying, most of them becoming expelled from their host pearl oyster; but in exceptional occasions something truly special happens: the pearl oyster will cover them with mother-of-pearl, thus they become “nacreous mummies” or one of the most striking natural blister pearls you have ever laid eyes on.
These small nacreous coffins become an enduring testament to the lives of these rare inhabitants of our seas: all Life is important to keep an adequate Balance, and pearl oysters -as you have been able to ascertain with these last entries- are a key player in many marine environments, not only due to their main biological function but also to protect and nurture so many other minor players.
Black Lipped oysters (Pinctada mazatlanica) have been found to contain -quite rarely!- these unique natural blister pearls with the dead remains of a “pearl fish” (Carapus dubius). The photo of the shell on the left can be seen on display at the Mineral Museum in Zacatecas, México, and the one on the right was photographed from NYC’s Natural History Museum’s collection.