Imagine you are a snake. You crawl along the path with a long slither behind you. You have no ears. Even if your eyes are big and developed, you can’t blink. So what happens when you see tasty prey?
In fact, with the exception of a few species that are adapted to daytime hunting, most snakes have extremely poor daytime vision. Usually they only see shapes, not details. This poor vision may be due to their evolutionary history as cave dwellers. You know, living in the dark, eyes don’t seem to be much use. But usually snakes can see very well at night. Their pits (one on each side of their heads) feel like night-vision goggles for heat (infrared light). These pits, rather than the eyes, are actually thought to produce images of prey in the snake’s brain.
Interestingly, cobras have very keen senses and can aim their venom at their eyes as they excrete venom. They seem to know that venom can blind humans or other enemies.