Question

There is a point in our eyes where no image is formed. That point is known as a blind spot. Which animal does not have this blind spot?
A) Fish
B) Ostrich
C) Octopus
D) Rat

Answer 1

Hint: Blind spots typically occur due to the location of the optic nerve within the retina. Predator animals usually have a big blind spot since both their eyes look in the forward direction to hunt their prey while the prey has fewer blind spots since they need to be aware of a coming predator from all sides.

Complete answer:
A blind spot is a small portion of the visual field of sight that corresponds to the position of the optic nerve head within the retina. There are no photoreceptors (i.e., rods or cones) in the optic disk, and therefore, there is no image detection in this area and the animal cannot see in that region.
Squid and octopus have evolved an eye layout that is remarkably similar to our own. They also have large eyes, with a lens, iris, which provide them with excellent vision in all directions. Like humans, the Octopus has a single layer of receptor cells that sends images back to the brain through the optic nerve but the Octopus doesn’t have blind spots because their optic nerves do not pass through the receptors but instead from behind them. So even the light coming from behind the eyes will interact with optic nerves which will send signals to the brain and the octopus will be able to see all around it.
Hence, Option (C) is correct.

Note:
To answer this question, we must be aware of the working of the eye and how blind spots are formed due to the lack of photoreceptors. Fishes, Ostriches, and Rats have eyes on the sides of their heads such that all of them have a blind spot at some point in their vision.