Pearls are harvested from __________.

Pearls are harvested from oysters, specifically a group of bivalve mollusks known as pearl oysters (genus Pinctada) [2]. While other mollusks like mussels and clams can produce pearls, high-quality gems are primarily obtained from species such as Pinctada maxima and Pinctada margaritifera [3]. The process begins when an irritant, such as a parasite or sand grain, enters the shell; as a defense mechanism, the oyster's mantle epithelium secretes layers of nacre (calcium carbonate and organic matter) around the intruder [2]. Over time, these concentric layers harden to form a pearl [1]. Japan is historically significant for developing pearl culture, where divers extract these shellfish from coastal waters [2]. In contrast, prawns are crustaceans, Pila is a freshwater snail (gastropod), and tuna is a fish, none of which are sources of commercial pearls [3].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Fishing Off Japan > p. 464
2. [2] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 24: The Cool Temperate Eastern Margin (Laurentian) Climate > FISHING OFF JAPAN > p. 230
3. [3] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 10: Locational Factors of Economic Activities > Fishing > p. 28