From the outside, it's impossible to tell whether an oyster is a he or a she. This, according to The Great Scallop and Oyster Cookbook: “There is no way of telling male oysters from females by examining their shells. While oysters have separate sexes, they may change sex one or more times during their life span.
There is no way of telling male oysters from females by examining their shells.
One fascinating discovery about the sex of pearl oysters is its influence on pearl quality. Males produce high-valued pearls compared to females. They also produce pearls with good features such as luster, smoothness and evenness, while the pearls produced by females have scratches and are uneven.
IT is well known that sex-change in the native oyster (O. edulis) occurs at some period of its life. This mollusc apparently always begins life as a male, and may change into a female at the age of one or two years.
So to once again answer the question, yes, oysters are alive when eaten immediately after being shucked. And the truth is, we wouldn't have it any other way! The amazing flavors of raw oysters and the overall experience of eating raw oysters is something that you must try.
A regular alternation of sexes between male and female apparently continues throughout life. This alternating lifestyle is advantageous because at any given time an oyster should have potential mates nearby.
Every season, an adult female oyster can produce 50 to 100 million eggs. Males produce so much sperm that it's basically uncountable.
Spawning causes hormonal and pH changes in bivalves—so called because of this mollusk species' hinged shell. Oysters are typically plump and firm; spawning makes them thin and flabby, and they'll taste like organ meat or raw egg yolk.
While all mollusks, including oysters, mussels, and clams can technically make pearls, only some saltwater clams and freshwater mussels are used to commercially grow cultured gem-grade pearls.
Today, natural pearls are extremely rare. Only 1 in about 10,000 wild oysters will yield a pearl and of those, only a small percentage achieve the size, shape and colour desirable to the jewellery industry.
Some pearl “farmers” will remove pearls from an oyster without killing them, keeping them alive to endure repeated insertions of foreign materials to continue making pearls. It is estimated that around a third to half of them are kept while the rest are killed.
Tap the shell. If it closes, that means the oyster is still alive and breathing. A shell that doesn't even close (or an oyster that comes gaping open) means it is D-E-A-D and you should not buy or eat it.
There is no obvious sign that an oyster has a pearl inside. You have to open the shell to see if there's one inside. However, larger, older oysters are more likely to have pearls.
Foodie tradition dictates only eating wild oysters in months with the letter "r" -- from September to April -- to avoid watery shellfish, or worse, a nasty bout of food poisoning.
You may have heard the saying that you should only eat oysters in months that contain the letter "r," meaning oysters harvested in the warmer summer months of May through August were not safe for consumption. However, oysters are now sold and consumed year-round with little to no worries.
If it looks veiny, with bluish or whitish channels through the flesh, that's a sign that it's getting ready to spawn and is filled with gamete, not glycogen. Prick a spawny oyster and its liquid will look milky.
Oysters have three-chambered hearts that pump colorless blood throughout their bodies. They breathe with gills, just like fish. Wild oysters can live 25 to 30 years, but typically most don't survive past six years.
Unless you are going to eat your oysters straight away, it's better to buy them unopened. Given the proper care, oysters will live for 5-7 days after being harvested. You can keep live oysters in the fridge.
Young oysters, called spat, are small, vulnerable and subject to numerous stresses in open waters.
"It also ensures food safety," she says. "Dead raw oysters run a greater risk of being infected with viruses and bacteria that can have a negative impact on your health—although the overall risk is relatively low," she says. Low or not, that's why they are in fact alive or freshly killed to keep you safe.
We always say that you can depend on a week of shelf life, but oysters can live for more than a month out of the water, if stored properly (see Storage FAQ). When an oyster begins to expire, the muscle holding the shell closed relaxes, releasing the life-giving oyster liquor and drying the animal out.
From tide to table, it takes approximately 18-24 months to grow our plump and briny bivalves.