Vision
Cats and Dogs
Dogs and Cats are typically considered color blind. Their vision can be compared to that of a human who has red-green color blindness. On the other hand, their peripheral (side) vision and night vision are far superior to that of humans. Their eyes are much more sensitive to movement. Their remarkable ability to sense movement is very helpful to them when hunting for food (although most dogs and cats no longer need to hunt).
Snakes
In daylight, snakes see just like humans do. They are dependent on movement because they are not known for seeing far distances. They often depend on movement so much that they fail to notice pray if it is completely motionless. On the other hand, when it gets dark, they see by sensing heat (infrared vision). Warm object (living things) will be lighter or turn red. Having the infrared vision helps snakes to hunt no matter what time of day it is.
Horses
Horses (and animals like zebras) have eyes on either side of their face. This gives them sight of two different pictures. It is to their advantage when a predator is coming because they are able to see it even if it is not right in front of them. On the other hand, if a predator were to come head on, the horse would have no idea. Horses have much better night vision than humans do but they mostly see in shades of gray, occasionally blue and green.
Insects
Insects have what is called compound eyes. They are several hundred and sometimes thousands of lenses placed together in the eye. This makes for a honeycomb pattern when they see. Each lens is just "one piece in the puzzle" of the insects vision. As for color, some insects, like butterflies, can see more colors than humans can. On the other hand, other insects, like a bee, can only see yellow, green, and blue. Bees are also able to see colors on the ultraviolet spectrum. Not all insects are the same and therefore sometimes have other ways of seeing. For example, in addition to the compound eyes, honeybees have three other eyes that cannot make out images but are able to sense light verse dark.
Shrimp and Crabs
Shrimp and Crab, similar to insects, have compound eyes so they see with many pieces put together but they are given much less detail than insects. The image on the left would show how one shrimp would see another. Although their vision is poor, they are very good at sensing movement. They are able to detects the smallest of moves by other creatures which is what makes them such good predators and helps they to not become pray.
Birds
Similar to insects, birds that are out during the day can see ultraviolet light. They see way more colors than humans do. Colors seem to be much brighter to birds but it is hard to know since humans are not able to see many of the colors that birds do. Hunting birds, like eagles, are known to have impecable binocular vision. Binocular vision is the ability to bring the image each eye sees and make it into one image (this is what humans do). They sharp vision helps they to spot pray at a distance that is not visible to most other species.
Sharks
A shark's eye is very similar to a humans although they do not have the ability to see color. Instead of color, their eyes are designed to detect light. This helps them navigate through dark and sometimes dirty waters. Although their vision is similar to humans, it is sometimes not as sharp as they tend to see images a little more blurry than humans would see.
Dichromatic vs. Trichromatic
A dog has dichromatic vision. This is the ability to make colors that only mix two different wave lengths of light. Humans have trichromatic vision. This allows them to make colors the mix three wave lengths of light. Those that can only mix two colors have a much narrower color spectrum as seen on the top left. These are the colors dogs typically see. On the other hand, trichromatic vision allows the eye to see many more colors as seen on the bottom left.