Oyster is the common name for a number of different families of salt-water bivalve molluscs.
They are found in temperate and warm coastal waters of all oceans.
The shell of oysters consists of two usually highly calcified valves (shells) that surround a soft body. Gills filter plankton from the water, and strong adductor muscles are used to hold the shell closed.
Some types of oysters known as the “true oysters” are highly prized as food. They are consumed both raw and cooked. Some types of pearl oysters are harvested for the pearl produced within the mantle.
Oysters have been around for a while. Estimates put the shellfish at around 300 million years old, at least.
Oysters were originally cooked by fire as early humans had primitive tools that would have made it difficult to open oysters to eat raw. Archeologists believe that oysters were placed over fire or heated stones and cooked until the oysters opened up as oysters from the Mesolithic period show evidence of scorch marks from fire. The use of fire by early humans evidence back to about four hundred thousand years ago, so consumption of oysters most likely began after that time.
The Stone Age, which was between 2.5 million years ago to 9600 BC, left behind fossilized oyster shells from many coastal civilizations, which demonstrated that oysters were an important part of the human diet for thousands of years.
Oyster cultivation was invented by Sergius Orata, a Roman engineer also often credited with the invention of underfloor heating, and since his invention, oyster farming has become big business.
In the United Kingdom, the town of Whitstable is noted for oyster farming from beds on the Kentish Flats that have been used since Roman times.
Oyster sales boomed from the early 19th century onwards, and the shellfish were sold as street food across London, Paris, and New York as they remained a cheap and accessible snack to many. In 1860, the small British seaside town of Whitstable alone was sending 50 million tons of oysters to London each year, and by 1900, New York was eating 1 million oysters every day.
By the 20th century, the overharvesting of oysters in the US and Europe was noticeable and it was difficult to maintain the oyster stock needed to meet demand.
Oysters can be eaten on the half shell, raw, smoked, boiled, baked, fried, roasted, stewed, canned, pickled, steamed, or broiled, or used in a variety of drinks. Eating can be as simple as opening the shell and eating the contents, including juice. Butter and salt are often added. Poached oysters can be served on toast with a cream roux. In the case of Oysters Rockefeller, preparation can be very elaborate.
Oysters are still alive as you eat them! In fact, if you are going to eat an oyster raw, it has to be alive or else it will no longer be safe to eat. In the case of oysters, alive means fresh! Trust us, you only want to be eating oysters that are alive.
Oysters are an excellent source of zinc, iron, calcium, and selenium, as well as vitamin A and vitamin B12.
In the northern hemisphere, the old rule that native oysters should only be eaten when there’s an ‘r’ in the month still holds true – so eat oysters from September to April. During the summer months they’re busy spawning, and their flesh becomes unpleasantly soft and milky. Rock oysters are available all year round.
The pearl oysters are well-known for producing large, commercially valuable pearls. Pearls form when an irritant – usually a parasite and not the proverbial grain of sand – works its way into an oyster, mussel, or clam. As a defense mechanism, a fluid is used to coat the irritant. Layer upon layer of this coating, called ‘nacre’, is deposited until a lustrous pearl is formed.
In addition to their commercial importance for culinary purposes and for the production of pearls, oysters provide important ecological values. Oyster reefs provide habitat for many organisms, and the oysters themselves provide food for various fish, marine mammals, and invertebrates. As filter feeders, they have a remarkable ability to filter water, removing pollutants and excess nutrients.
A group of oysters is commonly called a bed or oyster reef.
As a keystone species, oysters provide habitat for many marine species.
The largest oyster is a Pacific oyster (Crassostrea gigas) and measures 35.5 cm (13.97 in) in length and 10.7 cm (4.21 in) in width, as measured in the Vadehavscentret, Vester Vedsted. Denmark, on 17 December 2013. It was found by the Vadehavscentret (Denmark). The Pacific oyster (Crassostrea gigas) is from the Danish shores of the Wadden Sea and resides in the Vadehavscentret. This large oyster has another five oysters attached to it! In total, this cluster of oysters weighs 1.62 kg (3.56 lb).
The word “oyster” comes from Old French oistre, and first appeared in English during the 14th century. The French derived from the Latin ostrea, the feminine form of ostreum, which is the latinisation of the Greek ὄστρεον (ostreon), “oyster”.