All About Spiny Oyster

The spiny oyster, otherwise known as spondylus, is a large family of mollusks. They are sometimes also known as thorny oysters or spondylids. A bivalve mollusk, the animal is encased in a hinged shell composed of two parts. Large quills grow from their shells, providing this creature its famous moniker. Despite its name, these creatures are not true oysters and are more closely related to scallops. Of all the many varieties that are found in the seas of the world, two significant variations are found off the Pacific coast of Mexico. Both are harvested for their shells for use in jewelry and lapidary purposes.


Spondylus princeps possesses a striated shell, with lines of grooves running along the surface of the shell. Primarily, the shells are striped with fiery coral red and orange.


Spondylus calcifer  This species' shell is orange to purple in color, with reddish purple banding along the edge. The spines on this bivalve are shorter, but it grows to be larger and thicker in size. Orange spiny oyster occurs in shallow to moderately deep waters, where snorkelers and scuba divers can readily harvest them. Purple spiny oysters grow in deeper water, making them more difficult to find and harvest.


The flesh of spiny oysters is edible, and the mollusks are harvested for both shell and meat. The shell is made up of several parts, and the portion used to make inlays is known as Aragonite, a predominant form of calcium carbonate (CaCO3). After cleaning, the shells must be ground down with lapidary wheels to remove the quills. Similar to many other gems and stones, the shell is worked when wet. Wet grinding minimizes the production of dust.


In the ancient cultures that inhabited the American Southwest, Central and South America, the spiny oyster served many important purposes. Besides a source of nourishment, most of these cultures attributed a religious or ceremonial value to spondylus. Some cultures also used them as currency. There are Quechua myths citing spiny oysters used as religious offerings to deities.


Pre-Colombian peoples would harvest spondylus by free diving, a dangerous and risky endeavor. Divers would descend from a boat or raft to the necessary depth to collect the oysters in nets attached to ropes. These would then be hauled to the surface where workers would clean them on the spot. Interestingly, modern collection of spondylus hasn't changed much, the only difference being the use of underwater breathing equipment. Otherwise many of the techniques have remained unchanged. Spondylus is still collected by hand and net as they have been for hundreds of years.