rats born with no eyes

Question
I have pet rats and one was born without eyes, he is healthy and is the first one to find food, why did this happen?

Answer
A birth defect is all.  This is not uncommon. I would assume these are pet store rats?

He will do just fine, however.  How old is he now?  Rats do not depend on their vision for navigation anyhow, so thats all good news. They use their whiskers for many things as well as their tail. They also rely on their sense of smell, which is very keen, to determine many things. In fact during my studies on rat behavior, I found it fascinating how rats can figure out many things just from their sense of smell, some of the information they seek through sense of smell is even vital for their survival!  Rats travel in the dark in tunnels under ground. They will mark their trail with their own urine in which they will then use it to find their way back to their nest again. They simply seek out their own scent again and follow it safely home, which is why our pet fancy rats have what some of use consider an annoying and even nasty habit of leaving little dribbles of urine around usually when they are in foreign surroundings. The older they get and the more familiar they  become with their surroundings they are not likely to mark their turf any longer. However, the rat owner who has not really done their homework on rat behavior simply thinks the rat "grew out of it" and just stopped marking areas with urine only to be surprised to see they do it again if you take them into another room of the house they have never seen and away they go again, piddle here, piddle there, much to the rat owners dismay.

Whiskers? They tell alot for the rat too. They help the rat judge the width and even the depth of some areas.  They can tell if they have room to fit in an area just by the way they feel with their whiskers. If the whiskers touch the sides of the space they are in, such as a tunnel or tube/pipe etc....they will immediately back out of the area so they dont run the  risk of getting stuck.  They can also tell if someone is in the same room/area as they are by the vibration of their whiskers!

So there you have it, the rat and his remarkable senses that he was blessed with. Its almost like rats were equipped with all of this "back up" tools in order to be able to survive even the most  extreme circumstances.