What are oysters?
A: Oysters are salt-water bivalve mollusks that live in marine or brackish
habitats.
Almost all shell-bearing mollusks can secrete pearls,
yet most are not what?
A: Very valuable.
What is the largest pearl-bearing oyster?
A: The marine Pinctada maxima, which is roughly the size of a dinner plate.
In nature, pearl oysters produce pearls by covering a
minute invasive object with what?
A: Nacre.
Over the years, the irritating object is covered with
enough layers of nacre to become what?
A: A pearl.
The many different types,
colors and shapes of pearls
depend on what?
A: The natural pigment of the nacre, and the shape of the original irritant.
How can pearl farmers culture a pearl?
A: By placing a nucleus, usually a piece of polished mussel shell, inside
the oyster.
The oyster can produce a perfect pearl in what length
of time?
A: In three to seven years.
Since the beginning of the 20th century, when several
researchers discovered how to produce artificial pearls, the cultured pearl
market has far outgrown what?
A: The natural pearl market.
Oysters breathe primarily via what?
A: Gills.
In addition to their gills, oysters can exchange gases
across their what?
A: Mantles, which are lined with many small, thin-walled blood vessels.
What kind of heart do oysters have?
A: A small, three-chambered heart, lying under the adductor muscle.
What color is its blood?
A: Colorless.
Two kidneys, located on the underside of the muscle do
what?
A: Remove waste products from the blood.
Their nervous system includes two pairs of nerve cords
and how many pairs of ganglia?
A: Three.
There is no evidence that oysters have what?
A: A brain.
While some oysters have two sexes (European oyster and
Olympia oyster), their reproductive organs contain what?
A: Both eggs and sperm.
Because of this, it is technically possible for an
oyster to do what?
A: Fertilize its own eggs.
The gonads surround what?
A: The digestive organs.
Once her millions of eggs are fertilized, the female
does what?
A: Discharges them into the water.
The larvae develop in about how long?
A: Six hours and exist suspended in the water column as veliger larvae for
two to three weeks before settling on a bed and reaching sexual maturity
within a year.
Oysters are filter feeders, drawing water in over what?
A: Over their gills through the beating of cilia.
Suspended plankton and non-food particles are trapped
in what?
A: The mucus of a gill, and from there are transported to the mouth, where
they are eaten.
Oysters feed most actively at what temperatures?
A: Temperatures ranging from the high 60s to the high 70s.
Under laboratory conditions, an oyster can filter up to
how much water per day?
A: 50 U.S. gal.
Under average conditions, mature oysters filter how
much?
A: 3–12 U.S. gal (11–45 l) per day.
A group of oysters is commonly called what?
A: A bed or oyster reef.