Question

Osphradium of Pila globosa is a
a. Chemoreceptor
b. Photoreceptor
c. Thermoreceptor
d. Tangoreceptor

Answer 1

Hint: Sensory receptors are found in specialized organs like eyes, ears, nose, mouth, skin and internal organs. Some sensory receptors are:- thermoreceptor, photoreceptor, chemoreceptor, mechanoreceptor, tangoreceptor, phonoreceptor etc. Pila globosa have osphradium (sensory organs) that detect the test of water.

Complete answer:
Pila globosa is commonly known as pond snail or apple snail. It inhibits fresh water ponds, pools, marshes, rice fields and sometimes even in streams and rivers of north India. Pila is a voracious eater (consuming large quantities of food).

Pila are amphibious forms i.e., they live most of the time in water but they can also live well on land. They exhibit two folds of respiratory adaptations. They respire in water by gill and by pulmonary sac on land.

Sense organs of Pila are well developed. Osphradium is a sensory organ for taste and serves as an olfactory and chemoreceptor organ. It helps to test chemical and physical qualities of the water and also assist in the selection of food. It is a single structure found attached to the roof of the mantle cavity on its left and hanging over the inhalant siphon near the left nuchal lobe. It is small, elongated and somewhat oval.

> Option B: The retina contains millions of light sensitive cells called photoreceptors (photo means light). Two types of photoreceptors are:- Rods (more sensitive to light of low intensity / dim light) and Cones (sensitive to light of high intensity / daytime).

> Option C: Thermoreceptors are specialized nerve cells that detect changes in temperature. Thermoreceptors are categorized into hot receptors and cold receptors. Thermoreceptors are located in the dermis, liver, skeletal muscles and hypothalamus.

> Option D: Tangoreceptors are receptors which are stimulated by touch and pressure. The whole body surface is tangoreceptive.

Hence, the correct answer is option (A).

Note: Osphradium of Pila globosa helps to test the physical and chemical qualities of water for silt and possible food particles, that is why it is a chemoreceptor. It is also an olfactory organ in few molluscs which are linked with the respiration organ.