Question

In elephant, external nares occur
A. Adjacent to mouth
B. Sides of trunk
C. Tip of proboscis
D. Base of trunk

Answer 1

Hint: Elephants are considered as the largest mammals on the earth with a long history in terms of their evolution process. Elephants lack pleural cavities and this is the reason that their lungs are found attached to their diaphragm and chest walls.

Complete answer:
In elephants the respiratory movements during respiration is dependent on their chest musculature. They do not have the breathing system like humans which is based on pressure created in the pleural cavities. In elephants the air enters through their mouth, internal nares which are present on the forehead of the elephants and external nares. Let us analyze the options to find out the correct option.

Option A: Elephants breathe air through their mouth but the external nares which are also used for the process of breathing in air are not located adjacent to the mouth of elephants.Therefore, this is the incorrect option.

Option B: External nares are part of the respiratory system of elephants. They are not present on the sides of the trunk as they are found on the tip of the proboscis. Therefore, this is the incorrect option.

Option C: External nares are the part of the elephant's respiratory system through which they breathe in the air from the external environment. This is present on Tip of the proboscis of elephants.Therefore, this is the correct option.

Option D: External nares are part of the respiratory system of elephants. They are not present in the base of the trunk as they are found on the tip of the proboscis.Therefore, this is the incorrect option.

Hence, the correct answer is option (C)

Note: In elephants, the mechanism of lung inflation by negative pressure in the pleural cavity is absent due to the absence of the pleural cavity in them.