can someone explain the formation of pearl in seas?

Answer 1

A bit of sand or something smaller gets inside of a clam and it coats it to stop the sand from irritating it.

Clams are filter eaters; they suck in water, extract the plankton and algae from it and spit the water out. Occasionally they get a grain of sand stuck inside. It is soft and tender inside so the clam tries to flush out the bit of sand. If it can't then it starts laying down a natural coating around the bit of sand to make it smooth.

According to Wikipedia: http://en.wikipedia.org/wiki/Pearl
"As a response to an irritant inside its shell, the mollusk will deposit layers of calcium carbonate (CaCO3)."

The calcium carbonate forms a smooth surface and it keeps depositing more calcium carbonate since it still thinks the new pearl is an irritant. If you pry open an oyster and introduce a seed bit of grit inside then you can make an artificial pearl. However, these pearls have that seed material at its core. A natural pearl is "Natural pearls are nearly 100% nacre" (nacre is calcium carbonate deposited in a shell i.e. the stuff of the pearl). The seed is microscopic where in artificial pearls the bigger the seed the faster the pearl can be grown. It takes years for a pearl to be made.

It is easy to detect real pearls if you rub them on your teeth they should be smooth, if not then you have a fake set.

Answer 2

The real reason behind the natural formation of a pearl lies behind a biological intruder: a parasitic organism. These may be drilling worms (polychaetes, such as Polydora), a drill-mussel (like Teredo) or many other kinds of organisms (like the drill-sponge Cliona or even the cysts of worms). When a parasite drills thru the shell of the pearl oyster, the oyster becomes irritated and uses its only means of defense to form a barrier: the mantle. This unique organ covers all the inside of the shell of the oyster and is responsible for the secretion of the pearly substance know as mother-of-pearl or nacre. The oyster will use its mantle to secrete nacre on top of these nasty intruders and, if lucky, will coat them and turn them into natural pearls. Very few natural pearls will be of good size (bigger than 8 mm) and of good quality, and those that do are able to fetch very high prices.

Answer 3

Oysters and other shell-forming molluscs make a special substance, called nacre, that lines the insides of their shells. This smooth lining is called the nacreous layer, or pearly layer, and is often lustrous. It is formed by cells from a fleshy body organ called the mantle.
When a foreign substance, such as a bit of shell or a tiny parasite, enters the body of the mollusc, the mantle cells begin to work. They cover the invading substance with thin sheets of nacre. They build successive circular layer of nacre until the foreign body is enclosed in the shell-like substance, forming the pearl.

Answer 4

When a foreign substance enters an oyster, it secretes an substance called Mother-of-pearl and coats it around the foreign substance. Most natural pearls are not really round and nice. Most round pearls are cultured.

Answer 5

This is not the Textbook version, but it's when an oyster gets sand trapped in its shell. The creature then slowly builds a layer around the bit of sand. The added layers become the Pearl.
Then its gets fished out and voila!

Answer 6

The substance that the oyster secretes around an irritant is called NACRE and it is the same stuff it lines its shell with. Also known as 'Mother of Pearl'.

Answer 7

An oyster gets sand inside it, calcium is deposited around the sand and it becomes a pearl over time.

Answer 8

when an external paticle enters an oyster's shell it irritates the oyster and to stop the irritation the oyster covers/wraps the external particle with a certain secretion... producing a pearl