Oysters.us - Spat Perceptions Introduction

Looking over the Seafood Display (and Who's Behind It)
John McCabe

Somebody is merely selling you some seafood. You and your loved ones, however, will be eating it. Although you are responsible for the continued care of any fresh food from the moment you buy it, looking over food on display at the store a bit before you buy it, particularly seafood, is a real good idea.

Regardless of whether the seafood display is located in a seafood store or in the seafood department of a supermarket, it is always exciting to look at, particularly if many different fish and shellfish types are offered. Slow down, take your time, marvel a little at the bounty the sea provides us - and also pay close attention to details. This is particularly important when it comes to fish and shell stock clams, mussels, and oysters.

Most of us know to watch for signs of the potential beginnings of spoilage with whole fish. Their eyes are sunken and cloudy. The gills may have an obvious gray or green tint. The fish's flesh has lost its rigidity, has become soft as evidenced by a finger or fingernail indentation that stubbornly retains its form in the flesh. A smell reminiscent of ammonia is highly undesirable. Shucked oysters in plastic jars are also found in these refrigerated displays. They are pretty straight forward. By law the shucked oyster jars are all properly labeled and dated. If by some rare chance the shucked oysters smell odd or bad once you open the jar at home, just put the lid right back on the jar, wash your hands, put the jar in a plastic bag, and take it back to the vendor. Oyster meats should smell fresh, reminiscent of the ocean shore, perhaps even a little earthy, and always pleasant. Don't worry: Your nose will know.

Qualifying Oysters in the Shell in the Seafood Display
Let's take a closer look at the shell stock oysters the seafood vendor is offering.

* Gapers
Frequently the oysters in the display are presented in a big heap. Look at this pile closely and check for so called "gapers". Gapers are oysters whose two shell halves are not shut (i.e. an opening is visible between the two shell halves). This is not a problem as long as an oyster shuts down tightly once it is handled. If it does not shut down, the oyster is very likely already "deader than a doornail". A few dead ones in a big pile of oysters is no big deal, as all oysters have a peculiar way of choosing to die at their leisure - sometimes even if they are perfectly fresh. The fish monger certainly can't "check their pulse" day and night. However, discovering a dozen or so dead ones in a pile of say 100 oysters or so, is a problem. Here's why: A dozen oysters in a big pile dying overnight or in the course of the day is no real cause for alarm. That could conceivably happen with the freshest oysters straight from a grower. However, the fact that that many dead oysters are still left in the vendors seafood case at the time you are ready to buy some, is very just cause for concern. Either the person behind the display is to busy (or lazy) to tend to his/her seafood case, or worse, the oysters have reached their shelf life limit and are dying so fast that he or she can't keep up with removing the casualties. In either case: Just stay away from all of those oysters. In fact, it is my opinion to best stay away from anything else the fish vendor is peddling as "fresh". Go elsewhere for your seafood.

* Broken Shells
Don't buy oysters with damaged shells. The shell is broken when it has a prominent crack or a hole. Any fish monger that knowingly sells you obviously damaged oysters, clams, or mussels is definitely in the wrong business and does not deserve your hard earned money. Go elsewhere for your seafood.

* Oyster Shell Cosmetics

A "honeycombed" look and mud blisters cosmetically compromise an oyster's shell and reduce its trade value considerably in the half shell market. The former condition can easily be recognized by just looking at the shell outside. The latter, mud blisters, is impossible to ascertain without opening the oyster. However, the honeycombed condition may precipitate the existence of mud blisters. Neither of these two factors usually affects the oyster meat itself. Although both types of organisms can severely weaken the oysters shell layers, they only rarely manage to kill the oyster within, as it compensates by strengthening its innermost shell layer. Both conditions are associated with bottom cultivation and natural growth harvesting. They are only rarely encountered with more sophisticated (and costly) off-bottom oyster growing techniques (such as rack and bag and long-line). Although honeycombed oysters are usually fine for cooking purposes, they are undesirable where the perfect presentation of oysters on the half shell is desired. A few more details on this topic:

Sometimes, oyster shells are perforated with countless little holes. This "honeycomb" look is caused by a multitude of small boring sponges (among them the species Cliona lobata, C. celata, , C. spirilla, C. truitti, and C. vastifica). The condition tends to weaken the outer and central shell layer of the oyster. In rare instances, the innermost layer upon which the oyster's flesh rests, can also be damaged. In any case, the shell is crumbly and, in severe cases, substantial outer shell fragments may readily break off during handling and opening (shucking). Unfortunately, the tunnels these boring sponges create can readily host other organisms such as mud worms.

Optional images of a severely afflicted specimen. Although it unfortunately does not show well in my pictures, the adductor scars on both valves are excessively recessed and deformed. The oyster's meat, however, was entirely unaffected and proved to taste delightful. 1. Right valve outside 2. Right valve inside 3. Left valve outside 4. Left valve inside

Mud Blisters
Small black dots or dark channels can occasionally be present on the inside of an oyster's shell. They are called mud blisters and are caused by small mud worms (most notably the species Polydora websteri). The oyster continuously covers these imperfections naturally with layers of its shell material. Hence they are meaningless as long as they are not punctured with the oyster knife tip or an oyster fork, as they may emit an unpleasant mud odor.


Oysters rarely travel alone. Given a choice it is best to pick oysters with the least amount of animal life attached to the shell. For instance, an oyster covered with barnacles will taste just as good as one that is not. However, it is more likely to start to smell spoiled after a few days in the refrigerator as some of the barnacles likely are already dead due to damage during transport. High and dry in the crisper drawer of the fridge, the rest will die well before the oyster floating in seawater inside the shell will. Although I never pass up fresh oysters with lots of barnacles attached, I do give 'em a quick scraping and scrubbing in a colander under running water (usually outside) once I get the animals home to get rid of the hitchhikers.

* "Potato Vendors"
If you've visited a number of seafood vendors in your day, you may recall the oysters in the display arranged pretty much like a big pile of potatoes. Regrettably, many seafood vendors apparently don't know the difference between a vegetable and a living animal. As mentioned earlier, the most common oysters found in stores are the Pacific oyster (in North America and Europe) and the Eastern oyster (North America). Their shell fortress features a rather flat shell on top and pronounced cupped or "belly like" shell on the bottom. It can't get any more obvious. The belly part naturally traps some sea water in which the oyster floats. This helps keep it juicy and alive. Hence one does not need to be a rocket scientist to figure out that an oyster sitting "belly up" in a seafood case (or at home in the refrigerator) is more likely to loose its "bath water" much more readily than if it is placed "belly down". Rule #1 when storing any oyster: Cupped portion of the shell down! Any seafood vendor that is either too lazy or to busy to arrange his living oysters a bit accordingly may not be deserving of your business - particularly if the oysters are destined to be slurped raw off the half shell. Nothing irks me more than a bunch of "fresh" oysters I just paid for with my hard earned cash that have a dried out look after I open them. Without exception these "desert oysters" are immediately served to our cats - who incidentally love 'em. Ok. I confess that a flat tire on the way to work irks me more.

Conversely, if you find a seafood vendor that invests at least a little time in organizing his oyster pile properly, also gets rid of dead and broken shell oysters, mussels, and clams, stick with him (or her). He probably also knows what he is doing with the rest of his seafood. I believe that particularly the presentation of oysters, clams, and mussels serves as an excellent general indicator of the seafood merchant's quality overall. Please also note that even the best fish monger with the most beautifully displayed seafood in his clean case might inadvertently end up selling you a few dried out oysters in your batch. Regardless of his efforts in observing rule #1 after receiving them from his supplier, the oysters may have traveled upside down and sideways for days on end before he ever got them. It simply happens and at least he (or she) should be commended for handling his oysters the right way after others may have handled them wrong.

Pointer: If you knock on the top shell of an oyster and it sounds hollow, it frequently means that the oyster inside has lost much of its moisture and will likely appear dried out instead of juicy upon opening.

* The Baker's Dozen
As mentioned above, it is not that unusual to end up with a "compromised" oyster or two (dried out or dead) after buying a dozen oysters - even if the seafood vendor took real good care of his oysters. That can even happen when the oysters are purchased directly from a grower. Every oyster grower and every competent seafood vendor knows this. I have bought oysters from many growers directly. Most of the growers I've dealt with will customarily slip in an extra oyster or two along with the dozen or two I've paid for. Some seafood vendors will do the same. Rest assured that they can all count to twelve and the free extra oyster or two is certainly no oversight on their part. Everybody is bound to be happy with this type of transaction. If the dozen turns out to be perfect, then the few extras "on the house" are all the more appreciated. I find that a very wise and considerate gesture - one that I remember when I decide on where to buy my next batch of seafood. Some other seafood vendors are classic bean counters that would rather argue later about a dead or dried up oyster than spring for an extra oyster or two at no charge on the front end.

* Intro
* Fresh Oyster Types
* Looking over the Seafood Display (and Who's behind it)
* LiFo (Last in, First out) Shopping
* How many Oysters to Buy
* Buying Oysters on the Internet

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Health advisory: There is a risk associated with consuming raw oysters or any raw animal protein. If you have chronic illness of the liver, stomach, or blood or have immune disorders, you are at greatest risk of illness from raw oysters and should eat oysters fully cooked. If you are unsure of your risk, you should consult your physician.

Advisements on any errors discovered are most welcome: Contact
© 2014 John W. McCabe