Well, the Isle Of Wight ferry, of course. Why, what did you think I was going to say?
And now, two interesting pictures I took the other day of a friendly young cow. This is not a dinosaur, she’s merely yawning.
You may remember, I tried this research last summer. Now, finally I got close enough to take a picture that shows a cow’s eye in detail:
You can see it’s the same as those other herbivores the goat and the horse; if you look closely you will see that behind all that brown stuff IT HAS A RECTANGULAR BLACK PUPIL.
Don’t say you never learn nothing here. Next time I’m going to try and take a picture to show how extremely long their tongues are.
A Bad Guide 
Oh no, yet another round of rectangular eyes ! But I suppose it’s quite a sociable topic, since nearly everyone has something to say about it, like the weather. But unlike the weather, I feel almost obliged to make a contribution to this. And anyway we’ve had enough weather recently.
You seem to be imputing a connection between herbivoracity and rectangular eyes. I wonder if these are in some precise sense more simple than round eyes – in their construction, I mean. The pupil consists of two widened slits at right angles to each other. This is sufficient to see leaves.
One imagines that they would suffice for the evolutionary survival of herbivores, who don’t need to chase their prey, since plants don’t run away. Similarly, herbivores don’t run well or put up much of a fight when their predators come visiting – no more than do the plants the herbivores eat.
Round eyes, however, provide better vision in all directions, I would think. So they provide evolutionary potential that could favor variations in behavior – such as run after or away from things, since the round-eyed animal can visually track them better.
I would consider my speculations partly verified if zoological records show that non-herbivores never have rectangular eyes. There could be herbivores with round eyes, of course, but that would only show such animals are evolutionary slackers.
herbivores don’t run well or put up much of a fight when their predators come visiting
Perhaps this applies to domesticated herbivores, whose will to fight has been bred out of them, but I have read that a full-grown male deer, or even better, a moose, can put up quite a fight against wolves. I would think that wild horses also can hold their own against wolves. Those large hooves are not just to walk on. Sharp horns are not just for decoration either.
Well, an animal with sharp horns doesn’t need to see very well to defend itself, does it ? The horns provide the acuity missing in the visual field.
My hypothesis might be shaken if someone could point to an animal with rectangular horns and round eyes.
And I don’t mean rectangular horn-rimmed glasses.
herbivores don’t run well or put up much of a fight when their predators come visiting
Perhaps this applies to domesticated herbivores, whose will to fight has been bred out of them
In fact, there’s little correlation between meat-eating hunters and danger–you only have to compare the threat to a human from our Yorkshire terrier with that from an enraged elephant. You wouldn’t last two seconds in a race with a hare, either of you. And my goats are intimidating when they display their horns–that’s what our dogs seem to think, anyway. As for cows, they kill lots of people every year (by accident). So do horses and elk. Wild boars are the most dangerous of creatures, as are the above mentioned elephants, and giraffes, chimps, rhinos and hippos. Just because they don’t eat their victims, doesn’t mean you don’t have to watch out. One must never forget that Hitler was a dangerous vegetarian.
One must never forget that Hitler was a dangerous vegetarian.
Do you happen to have a close-up picture of his eyes ?
Bernard Shaw was quite dangerous, in his own way.
I got lost somewhere. Was Mike Tyson’s teacher a herbivore?
Now I feel stupid for not taking the opportunity to check for myself this Christmas.
Thank you for your diligence!
A quick round of internet searching leaves me not much wiser. I gather that most ungulates (not most herbivores — not the rodents, hares, hyraxes, elephants, …) have the horizontal rectangular pupil, but that it is especially visible in goats because of their pale iris. There seems to be an idea that this pupil shape is good for keeping an eye on the horizon, and for peripheral depth perception. I could believe that, even though we know of many ungulates who will fight effectively when cornered, the eye might have evolved this way among ancestors who dwelt in the vast plains of Africa and needed early warning of big cats.
I can’t tell whether a pupil like this keeps a constant horizontal width, with contraction and dilating occurring vertically; and I don’t know whether the structure is as Stu suggests.
Octopuses have rectangular pupils, too.
And toads.
Here are some good pictures & a reasonable explanation, if a little vague & confused.
It says that eyes don’t fossilize very well, so it’s hard to figure out exactly how they have evolved. Nevertheless the distribution of differently shaped pupils is good evidence of animals adapting to their surroundings; (I’ve cleaned up the language a bit, for comprehension):
Perhaps vertical slits allow more depth perception in the centre of the field of vision as well as giving protection from bright light. Despite what they say, goats don’t see well in the dark.
I don’t think there’s a direct relation between eating habits and pupil shape. Hitler probably had roundish pupils.
Your headline reminded me of the old NZ joke about getting milk from Bulls – something very easy to do here.
:-o!!!!
No tenía idea de que así fueran esas pupilas…
¡Jamás diría que no aprendo cosas nuevas en este blog!
¡Gracias!
Thanks, I find it very interesting too. I think it’s because I wouldn’t have expected to find a rectangular shape in an organic form like an eye.
Exactly, AJP! I had the same thought…
You wouldn’t expect a rectangular window to be as useful a shape as a circle for light to pass through, either.