They Are Not Oysters

Pteria, Mollusk, Oyster, Pinctada… what am I talking about? The beautiful pearl making species... they are not oysters, per se, so what are they?!

I just wrote a post where I used all of these words referring to one species of mollusk and I fear that you have NO IDEA what I am talking about! I can’t blame you! So I am going to talk through why I use all these completely unrelated terms.

First, an oyster.

We all know what those are, right? Many have been gobbled up while standing around a piece of plyboard, elevated by sawhorses, while enjoying the musky thick heat of the South Carolina coast. Yum! (actually, truth be told.. I am not a huge fan of eating oysters even though I enjoyed quite a few oyster roasts with my friends in Beaufort!).

But, you know what I am talking about, we all know oysters.

If we take it on back to our species classification in school that starts with animals…the classification moves from Animalia (Kingdom) to Mollusca (Phylum). I love using the word mollusk (mollusca, mollusc) because it casts a wide net. Mollusks include all bivalve species but other species as well including sea snails (which can occasionally form a pearl) and octopus (no pearls there!). But, I do feel very all-inclusive when I say mollusk because both saltwater and freshwater species are in the phylum mollusk.  Let's look at our Tennessee River mollusks that form our natural Tennessee River pearls:

Kingdom: Animalia

Phylum: Mollusca
Class: Bivalvia
Subclass: Palaeoheterodonta
Order: Unionoida

The most common families are the Margaritiferidae and the Unionidae.

So, we have these mollusks. And we have these oysters. Why are they called oyster? Well, it is a variation on the order Ostreoida.

Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Pteriomorphia
Order: Ostreoida
Superfamily: Ostreoidea
Family: Ostreidae

These oysters do not create our beautiful gem quality pearls. These are the oysters we eat! So, why do I refer to our pearl making gems as oysters. Well, it is easy to relate to! If you hear me say oyster you get a sense of what I am talking about, right?

But, let's get technical. What are the pearl bearing mollusks that we are breeding and harvesting pearls from. These are the Pinctada!

Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Pterioida
Family: Pteriidae
Genus: Pinctada
These species are P. mazatlanica, P. margaritifera, P. imbricata, P. maxima, etc.

In the Sea of Cortez we have the lovely Pteria genus creating the lovely Cortez pearls.

Kingdom: Animalia

Phylum: Mollusca

Class: Bivalvia
Order: Pterioida
Family: Pteriidae
Genus: Pteria
Species: P. sterna

So, they are not oysters although I might continuing calling them oysters, or mollusks, or bivalves ... but now you know what they truly are! Enjoy!

India