How does an oyster make a pearl?

Chargrilled oysters

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Oysters are another bivalve animal. In the case of all bivalves, the part of the animal that lines the shell is known as the nacre and the part of the animal that make up the outer shell is known as the mantle. A pearl is created rather by accident when something foreign gets stuck inside the mantle, thus the nacre builds up to protect the animal. This build up is known as the pearl.

Oysters, mussels, and clams all make pearls. However, they are most often seen in oysters. My theory is that the oyster shells are typically not as uniform in shape as clams and mussels and tend to grow according to their surroundings, making it easier for foreign junk to accumulate.

Why are there holes through some clam shells?

moonsnailholezd2The shell to the right with a hole through it was hinged to another shell of equal size with an animal living inside (in this case, a clam). Animals with two shells hinged together are known as bivalves. Often, in restaurants oysters and clams are shucked and served “on-the-half-shell” (Yum! I prefer them plain, but sometimes mix it up with ones with plenty of horseradish!).

Animals in the ocean do not have the luxury of someone shucking their prey, but rather use an adaptation called a radula. A radula is the sharp, drill-like tongue of some mollusks (e.g., whelk or conch). Radulas are found on every class of mollusk except for bivalves. A whelk or a conch would use their radula to drill into the clam and then slurp out its meal … Leaving behind a perfectly symmetrical hole. Moon snails and oyster drills are also well-known for using this technique to drill into clams for a feast.

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