The Mystery of the Spitting Oysters

Oyster reefby Nancy Hadley

I love oysters. And not just to eat, although I love a good oyster roast as much as anybody raised in the Lowcountry.

In fact, here is an aside, when I was growing up my parents belonged to a supper club which was (as far as I know) unique: it was an oyster roast club. I can’t remember how many couples belonged, but it wasn’t too many, maybe 10.

Each couple hosted an oyster roast at least once during the supper club season which ran from late October to early March. No sensible Lowcountry resident would eat oysters before or after that, it’s too warm (and the gnats will skin you alive).

The proper way to prepare oysters
Water before and after oysters have done their job.
Water before and after oysters have done their job.

So I grew up loving oysters. Back then we didn’t have oyster cookers on wheels and no self-respecting oyster roast host would cook their oysters in (or even over) water. Our oysters were roasted/steamed over a wood fire. We had a fireplace built to purpose. Oysters were shoveled onto a heavy steel plate and covered with wet gunny sacks.

You can’t even get a gunny sack these days – plastic has replaced burlap. If one of us kids was lucky enough to get to go to the oyster roast, which wasn’t a given, our job was to operate the hose used to keep the gunny sacks wet, but not too wet. So, yes, I love a good oyster roast.

But I haven’t spent 30+ years studying and taking care of oysters just because they are good to eat. Oysters are fascinating. And believe it or not, despite having been the subject of scientific inquiries for hundreds of years, not everything is known about oysters.

The mystery of oyster spitting
Sheepshead fish
Sheepshead

For instance, why do oysters spit? Nobody knows. Maybe you didn’t even know they DO spit. If you don’t believe me, go see for yourself. Position yourself where you can watch some oysters as the tide goes out. (A dock if you have one, or maybe the crabbing pier at the County Park.)

Just as the oysters emerge from the water, you will hear some clicking or snapping and small jets of water will spout up from the oysters, similar to the swimming pool trick of jetting water in your sister’s face by cupping your hands just so. The trick is repeated as the water comes back in 3-4 hours later.

What are they doing?? This was the first question which attracted me to a career-long love affair with oysters. I still like to sit outside on a still evening and listen to the oysters spitting. An unexpected symphony often accompanied by snapping shrimp. Try it sometime.

Nature’s natural filters
Smooth Butterfly Ray
Smooth Butterfly Ray

In addition to being yummy and intriguing, oysters are critical to our coastal ecosystems. Oysters are variously lauded as KEYSTONE SPECIES and ECOSYSTEM ENGINEERS. And it’s not just hyperbole.

Oysters are to South Carolina estuaries what coral reefs are to the Florida Keys. Oysters are nature’s filters, cleaning the water continuously as they feed. Oysters build complex reefs which provide habitat for small critters such as juvenile fish, mud crabs and polychaete worms.

Some fish such as blennies, gobies and oyster toadfish may live their entire lives on an oyster reef. Other larger fish and invertebrates are attracted to the abundant food supply on oyster reefs. Many of our most important commercial and recreational species rely on oyster reefs at some point in their lives. Shrimp, crabs, red drum, flounder, kingfish, spotted seatrout, spadefish, croaker, and sheepshead are just a few of the species regularly found on oyster reefs.

Terrific shoreline protectors
Summer Flounder
Summer Flounder

And it doesn’t stop there. Oyster reefs are natural breakwaters. North Carolina researchers recently demonstrated that oyster reefs are BETTER shoreline protection than man-made bulkheads! And they get higher every year because baby oysters attach to older oysters, and they all keep growing up up up.

In fact, a major limitation on the quantity of oysters is the fact that the reef gets too high. The oysters at the top are not under water long enough to get adequate food and are therefore stunted. So, as sea levels rise, we can expect that oyster reefs will also rise, continuing to provide protection for fragile salt marshes. No manmade barrier can boast that!

Are you starting to get the idea that I am passionate about oysters?

Read Part Two: Why are the oyster reefs in trouble?

Nancy Hadley is a marine biologist with the SC Department of Natural Resources where she heads up the Shellfish Management Program. 

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