Question

Nictitating membrane is useful to Frog in
A. Farsight
B. Short sight
C. Covering and protecting the eyeball from mud and water
D. Covering and protecting eyelids from mud and other particles

Answer 1

Hint: The nictitating membrane is called the plica semilunaris in scientific terms, sometimes referred to as the hawk or the third eyelid. The medial canthus of the eyes is drawn over it. In frogs and birds, the nictitating membrane is a human vestigial organ. It guards the eye.

Complete answer: Nictitating membrane is a type of membrane that is translucent or transparent and is drawn to shield the media canthus of the eye. It helps to keep the eyes wet. Fish, birds, amphibians, reptiles and some mammals have nictitating membranes and are rarely found in primates. Frogs have translucent eyelids; one below the eyelid, and the other at the top. The top of the pin shifts slightly. The third eyelid, i.e. the nictitating membrane covers the frog's eyes. In red-eyed frogs, the nictitating membrane looks like stripes of a tiger that cover the red-eyeball and provide a good view. It is also known as the haw that spreads from the lower lid of the frog and holds its hydration on the ground. There are no muscles, and it is the only epithelial tissues that link tissue collagen like the frog skin with blood vessels. Nictitating membranes are useful to protect the eyes from dust, mud and water. The membrane keeps the eyes clear.
Hence, the correct answer is option C.

Note: In some animals, nictitans or harder glans, is attached to the nictitating diaphragm and nearly 50 percent of the tear film is formed. It protects the eyes from water in diving animals like crocodiles.