For such small and innocuous creatures, there sure is a lot of lore about oysters. They have been mixed into soups and stews as peasant food, as well as food fit for a king — Louis the XIV of France was a fan of slurping them raw. Some produce precious pearls, while others are prized for their unusual shells. Most recently, oysters near urban centers are being recognized for their water-cleaning abilities.
In fact, you might be surprised at what you don't know about oysters — and what we're still learning.
1. Yes, oysters can hear. In recently published research, scientists subjected oysters to low-frequency sounds like those made by cargo ships, human-caused explosions and wind turbines. It caused oysters to clamp their shells shut. Higher-frequency sounds like those made by a speedboat didn't seem to bother them.
When oysters close their shells tightly to keep noise pollution out, it can alter their natural rhythms, Jean-Charles Massabuau, research director at the French National Center for Scientific Research and an author of the study, told The New York Times. Oysters need to hear be able to hear rainfall and tides to give them info on when to spawn or to "...prepare them for eating and digesting, possibly as when we hear and smell that somebody is preparing dinner," said Massabuau.
2. Oyster eating is ancient. Archaeologists know that when they've found a pile of oyster shells, they're not far from a human gathering place or town — possibly an ancient one. The oldest oyster middens (shell heaps) have been radiocarbon dated to 4,000 B.C., and oyster eating has thousands of years of history among Native Americans along both coasts. It's also part of the historical record in ancient Egypt, Greece and Rome, medieval France and England, and among the Mayans.
3. Oyster shells are great for your garden. Those of us who have lived in coastal communities have probably seen clam, mussel and oyster shells used as decoration in home gardens, but they're more than just pretty edgers. As the shells break down, they release calcium into the soil, which can improve soil pH and lead to healthier plants.
4. Oysters have made their way into not one, but two Shakespeare plays. "Why, then/the world's mine oyster/Which I with sword will open," is from "The Merry Wives of Windsor" and is the origin of the famous phrase. "As You Like It" includes the less well-known line, "Rich honesty dwells like a miser, sir, in a poor house, as your Pearl in your fouled Oyster."
5. Oysters clean the water. Every day, a single oyster filters about 50 gallons of water. They do it by pulling water over their gills, which trap nutrients and algae — and the water leaves the oyster cleaner than it came in. In some places that used to have huge oyster beds, like the Long Island Sound off the Connecticut shore, oysters are being brought in to both detox the waters and create a local food source. In New York City's most polluted waterways (over 350 acres of oyster beds historically existed there), oysters have been reestablished over the last decade specifically for water cleanup.
A cluster of Olympia oysters. (Photo: Oregon State University/flickr)
6. Groups of oysters create habitat for other sea life. When oysters multiply over an area, they form reefs or beds, which in turn provide anchors for others to attach to (think sea anemones, smaller bivalves and barnacles). Those then attract small fish and shrimp, which bring larger fish along as well.
7. Oyster beds protect against the effects of climate change. A reef made up of oysters not only cleans the water and creates habitat, it also can mitigate coastal flooding and erosion by absorbing 80 percent or more of wave energy, which is especially valuable during large storms. And, oysters are cheaper than human-made solutions that do the same thing, like bulkheads.
8. They won't up your libido, but they might keep you from catching a cold. Oysters contain high levels of zinc, which keeps the immune system strong. So while there's no proof that they are an aphrodisiac (they may boost testosterone a bit, but not enough to make much difference), they could keep you healthier during cold and flu season.
9. In many places, just 1 percent of oysters that used to exist, still do. In the video above, the history of oyster harvesting in the Chesapeake illustrates how millions of oysters were once canned and shipped fresh all over the United States. This demand for oysters in middle America led to over-harvesting in the Chesapeake, which caused populations there to crash. Diseases ravaged the oysters, and habitat was disturbed, leading to further declines. Worldwide, The Nature Conservancy reports that 85 percent of oyster reefs have been lost, leading them to call shellfish reefs, “the most imperiled marine habitat on earth.”
10. But it's not impossible to restore oyster populations. Providing appropriate habitat and a little help in seeding oysters in historic areas where they lived has seen oyster populations rebounding — though plenty more work needs to be done to get even close to the levels we saw 150 years ago in most waterways.