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Max Munro

Dr Mal, I was wondering how come Mandy got kicked by a horse that knew her. He wasn't sick or frightened or anything. I was thinking what you said at the funeral and wondered if you could explain it a bit more--about how horses see, I mean. It would be useful for my project at school on horses.

Dr Malcolm Malverson

Have a look at horses' eyes--where they're placed on their head.

Max

Can we? I mean, go to the stable and have a look at Dreamy, for instance? After you've finished your drink?

Dr Mal

I can take this with me. Just one last asparagus roll. Do you want to bring something?

[walking sounds, conversation, creak of stable door, etc...]

Dr Mal

Here she is.

Max

Too old for riding school, anymore.

Dr Mal

Horses have excellent peripheral vision. With their eyes placed on the side of their head like that they can see in front and behind without having to turn their head. Of course they can't see directly behind them.

...

I bet you've seen Dreamy standing in the paddock with her head up, looking into the distance at nothing at all.

Max

Uh-huh.

Dr Mal

Well, her vision is so accurate she was probably looking at something you could only see with binoculars.

Max

Dr Mal, while Dreamy's looking at me now... She can only see me with one eye. Does that mean she can see two different things at once?

Dr Mal

Lots of animals are like that. Probably they see mainly what they're concentrating on and are vaguely aware of what they're picking up through the other eye.

Max

Can she see in colour? Or does she see like a dog, in black and white?

Dr Mal

She sees much better than a dog, which specialises in scent and sound. But a horse's retina has mostly rods and hardly any cones. Rods are little cells (shaped like rods, of course) that are sensitive to different intensities of light. Horses' eyes have lots of rods that are sensitive to very weak light--so they can see well at dusk or in twilight. But, like most mammals, they probably see very little colour. The cone-shaped cells pick up colour. And there are hardly any cones.

Max

So she just sees in black and white?

Dr Mal

No, more like greyscale on your computer screen, only a thousand times clearer.

Max

Uh-huh. Why don't animals see in colour then?

Dr Mal

I suppose it's not that useful to them. I haven't really thought about it. I mean, when horses evolved, in the wild, what sort of situation were they in?

Max

I saw on a CD-ROM that the first horses were small and lived in herds.

Dr Mal

Well, what sort of information does a herd animal like that need?

Max

To know where the other horses are.

...

To know if there's danger...

Dr Mal

Exactly. While they're browsing on the grassland...if they can see a long way and pick up any little movement in the distance then they can get good warning of danger.

Max

Especially as the first horses were small, so lots of animals could attack them.

Dr Mal

Yes, indeed. And if they were running away on in a herd they would need to have a good idea where they were in relation to the other horses. Again, good peripheral vision is a must.

Max

But what about colour?

Dr Mal

You're a good interviewer, Max&Let me think for a moment. What are the mammals that can see in colour?

Max

Humans&monkeys I suppose, apes?

Dr Mal

Yes. We're called primates. Now what sort of things do we eat that horses--grazing animals, don't.

Max

Fruit and vegies? Meat?

Dr Mal

What sort of things do we eat that carnivores (cats and dogs, whatever) don't eat?

Max

Fruit and vegies. Grains?

Dr Mal

And when you eat fruit, do you like it ripe or unripe?

Max

Ripe, of course.

Dr Mal

And how can you tell that fruit is ripe when it's hanging in a tree, whatever?

Max

Oh, I get it. By it's colour! So fruit-eating animals need to be able to see colour. Why fruit is so important, of course, is another story.

Dr Mal

Like birds, for instance. But for most mammals, they get close enough to their food (if it's vegetable matter) to be able to smell, taste, feel if it's right for them. And if they're hunters they can see their target&their prey&move. So being able to see movement and being able to see at a distance are important. 

 

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