KEY POINTS:
The season all oyster lovers look forward to is upon us.
The first Bluff oysters are due on Auckland restaurant tables this lunchtime, but how much do you really know about the slippery little bivalves which command such high prices?
We've trawled for information on the sought-after delicacy so you can brush up on your knowledge of just what it is you're eating...
Suitable for a romantic evening?
It's long been said that oysters are an aphrodisiac and there may be some truth to the rumour - though the reason for it is hardly rocket science.
Oysters are packed with zinc, which controls levels of the hormone progesterone. In turn, progesterone levels are known to affect a person's libido. Although other shellfish also contain zinc, oysters have it in much larger quantities.
So yes, they may have the effect of an aphrodisiac, but you'd probably have to eat quite a lot for the result to be marked and it apparently helps to eat them raw - not that real connoisseurs would have it any other way.
Casanova, the 18th-century playboy, was said to be a fan.
Pearl of a feed
Although pearls do sometimes form in edible oysters, they are unattractive and have no market value.
Edible oysters belong to the Ostreidae family and are known as 'true oysters'.
Pearl oysters however, belong to the Pteriidae (feathered oyster) family and are only distantly related to their edible cousins.
An age-old delicacy
Oysters have been harvested commercially at Stewart Island since the 1860s but there is evidence they have been cultivated and enjoyed for much longer in other parts of the world.
The Romans were responsible for creating the first man-made oyster beds and heaps of oyster, mussel and scallop shells have been discovered during excavations of Roman ruins.
Today edible oysters are cultivated on the United States' east coast, on most European coasts, in Japan, the Gulf of Mexico, Chile and parts of the Pacific and Australasia.
All about the taste
New Zealand's main oyster-dredging areas are Nelson/Marlborough and the Foveaux Strait. Bluff oysters owe their reputation to the fact they are grown slowly in the cold, clear waters in between the South Island and Stewart Island.
Many consider them to be the best oysters in the world.
In an oyster-shell
Oysters are bivalve molluscs, meaning they have two shells (valves) which are joined by a flexible joint and held together by a strong muscle. The shells protect the oyster's soft body flesh.
Oysters are hermaphrodites and continually change their sex throughout their lives. They generally breed as males first before switching to become female. Both male and female oysters can produce eggs.
Oysters can take up to eight years to reach legal size and feed by drawing water in through their gills and filtering it to find plankton and other edible particles.
Aw, shucks
The process of opening an oyster is known as shucking and employs a specially designed knife to sever the muscle and prise the two shells apart.
Oyster shucking has become an art form and there are competitions held worldwide. The opening record is about 1700 an hour and an average oyster shucker can open around 1100 per hour.
Promoting regeneration
A quota system was introduced in 1963 to help preserve Bluff's oyster population.
In 1991, the Bluff oyster beds were closed for three years after they were struck by the parasitic protozoan Bonamia.
Since the harvest resumed in 1994, the industry has self imposed an annual quota of 7.5 million oysters - down from 14.95 million in the season before Bonamia hit.
In New Zealand, the oyster season runs from March until August each year.
Sources: bluff.co.nz, askmen.com, Wikipedia, associatedcontent.com and Newstalk ZB
