How much would a third eye help on creature with side-facing eyes?

[Greywander]

I saw a creature in a YouTube thumbnail, a monster from The Witcher 3 that spawns and kills you if kill too many cows or something. Anyway, the creature looks like some kind of minotaur, so it has side-facing eyes like a cow, but it kind of looks like it has a third eye on its forehead.

Normally a third is pretty redundant on a creature with forward-facing eyes like a human. It might give you slightly more accurate depth perception, but it's a negligible benefit and from a biological standpoint it's pretty inefficient. But on a creature with side-facing eyes, it could be a different story. Creatures with side-facing eyes are generally prey animals who need to maximize the awareness of their surroundings. That comes at the cost of binocular vision. With a third eye on the forehead, though, they could get a very broad field of binocular vision with either side eye. This does probably mean that such a creature would rarely look at something head-on, but rather tilt their head to one side or the other so that the side eye doesn't have to strain so far.

I just thought this was interesting to think about. As I said, a third eye doesn't have much practical use for someone like a human, and is usually symbolic of some other kind of supernatural power. But for a creature with side-facing eyes, it could actually be somewhat useful, giving the benefits of both side-facing and forward-facing eyes simultaneously.

I honestly wasn't sure if this was the right forum for this topic, but it didn't seem to fit anywhere else.

[Khedrac]

Perform a web search for the Tuarata - it is a creature with side facing eyes and a third eye on the top of its head.

The problem with a question like this is the answer is always "it depends". Under some circumstances the thrid eye will be useful enough to be selected for as a survival characteristic.
In others it won't.
And in others, depending on the "cost" of the third eye (e.g. does the brain processing required to operate it impact the processing of the main eyes) it may be selected agianst as a disadvantage.

I would [U]guess/U] that in the tuatara's case it give a chane to spot predators swooping in from above and to tak evasive action in sufficient time. For this the vision doesn't have to be very good, just enough to detect "incoming movement above".

Now a third eye on the human face has little benefit I agree, but one on top or the back of the head could be really useful in circumstances where humans are on the menu for other predators.

[Razade]

Perform a web search for the Tuarata - it is a creature with side facing eyes and a third eye on the top of its head.

It's spelled Tuatara. It, and several other species, have a Parietal Eye though they don't function like an actual eye. In the case of Tuatara we're not really sure what it's function is but it's covered in scales and doesn't process information the same way its other eyes do. It appears that in a lot of these cases, there existed an actual socket for the eye but now they're just simple detector organs at best.

[Khedrac]

It's spelled Tuatara. It, and several other species, have a Parietal Eye though they don't function like an actual eye. In the case of Tuatara we're not really sure what it's function is but it's covered in scales and doesn't process information the same way its other eyes do. It appears that in a lot of these cases, there existed an actual socket for the eye but now they're just simple detector organs at best.

Bah - my typing is not very good - I spelt it correctly the other times I used it. :smallfrown: Thank-you for the correction.

[Bohandas]

Perform a web search for the Tuarata - it is a creature with side facing eyes and a third eye on the top of its head.

The Tuatara's third eye only senses light and dark IIRC.

If you want a tetrapod animal with actual image forming additional eyes you have to look to the pit vipers and their relatives