Phobos, IIRC, giant squid are preyed upon by sperm whales, and many sharks, fish, spiders, and ameobas are also preyed upon.
And actually, it’s a food “circle”, without a top, or to be even more precise, a huge mass of small, thin, tangled, delicate strings that form a huge spherical jumble that has sunlight shining on the green side. The great white shark, however, is not preyed upon while alive (ignoring human beings). It’s devoured after it dies.
Interesting that so many acquatic animals were pointed out so quickly. I’d imagine one reason the relation doesn’t hold there is that vision is pretty limited under water. Sharks are much more dependant on their electrical senses, for instance.
Owls are interesting, too. Their eye placement also helps their hearing. It’s set up so that if they hear a noise equally in both ears, they’re looking directly at the source.
What about eagles, hawks, etc? I’m having trouble picturing one in my mind well enough to tell the position of their eyes. I think they’re forward-placed, too, though.
I think everyone is getting a little caught up with this whole “Every predator is really someone else’s prey” thing. I think the OP is referring to what is traditionally thought of as a hunting carnivore. Even if this is true, certainly I would expect the ongoing process of evolution to be such that an animal might fill a new niche allowing it to be a “predator” before the selective pressure would occur that would lead it have an eyes-forward physique. In fact, if what everyone is saying is true (i.e. all predators are also prey) then selective pressure of being prey would favor eye positioning towards the sides.
In short, I suspect that “predators” that have their eyes forward are those that are fast and can avoid being prey themselves (i.e. birds) whereas others where perhaps they can’t escape as well have eyes on the side (i.e. fish). The perfect animal, of course, then must be the puffer fish since it has those cool in-between eyes that can move independently.
Smeghead, yes. Birds of prey have binocular vision (forward-facing eyes). That includes hawks, eagles, falcons, caracaras, etc.
Intresting note on some owls: their ears are located on different heights on the head and are shaped differently. That results in a bigger difference between both ears, and thus an increased ability to dectect the location of the sound source. Not only that, but the ears are on both sides of the head, so they have one on the left and one on the right!
Yarster, not all predators are also prey to something else (assuming we are not including immatures). But all are devoured by carrion eaters after they die. For example: the osprey has no animal that might eat it.
Whew! Somebody FINALLY said the secret words–“depth perception”.
Sledman, anything that needs to jump and catch something to eat needs depth perception. Depth perception is what you get with two eyes facing frontwards, with binocular vision. It doesn’t have anything to do with mammal/reptile/bird, it has to do with what it eats. If it eats something that likely to jump two feet to the left when pounced upon, then it’s going to have eyes facing front, and depth perception. If it eats something that isn’t going anywhere, like grass or slow-moving insects, then it has eyes facing to the side and behind it, to watch out for the guys that DO have depth perception. Creatures like robins that pounce on things that don’t move very fast, split the difference, and have eyes sort of facing frontwards and sort of facing to the side. Hawks and owls have eyes facing front. Frogs have big bulgy eyes that look like they’re pointing to the side, but they can swivel them around to the front to give themselves depth perception.