No. 10 - Rat

No. 10 in our countdown of smartest animals is the rat, a highly intelligent yet much-maligned animal in Western cultures. Widely used in research, the lab rat has been known to find shortcuts, loopholes and escape routes in the laboratory experiments designed by the top scientific minds of our time. In Chinese culture, the rat is revered for its cunning and resourcefulness. And for good reason - the rat has successfully colonized every continent on Earth except for Antarctica. And if history is any indication, they'll be there too soon enough.

No. 9 - Octopus

Kudos should go to the invertebrate with the strength and skill to screw a lid off a jar! No. 9 in our list is the octopus, one of the smartest creatures in the sea. This animal is still poorly understood, but scientists are constantly discovering new and impressive octopus abilities. They play, solve problems, navigate through mazes and have a respectable short-term memory. But how is an animal that belongs to the same class as the snail capable of such clever feats? It may be that the combination of strength, agility, curiosity and a lot of brainpower sets the octopus apart from its soft-bodied brethren.

No. 8 - Pigeon

Pigeons are abundant in most major cities of North America, but most people think of them as mere pests. However, this ubiquitous bird is actually quite smart. Because pigeons have been the subjects of countless scientific experiments, there is a wealth of knowledge about their intellectual abilities. For example, pigeons can recognize hundreds of images even after several years have passed. They can also identify themselves in a mirror, be taught to perform a sequence of movements and to discriminate subtle differences between two objects - pretty impressive for a mere pest.

No. 7 - Squirrel

This animal's dogged persistence and impeccable memory have made it the nemesis of gardeners throughout its vast range. Most squirrels display an impressive array of tricks and strategies that help them survive. For starters, these clever creatures are essentially woodland animals that have adapted to living alongside humans, eating out of bird-feeders, flower gardens and whatever food might be lying around. They are also able to store and cache food for leaner times, and then find their hidden morsels many months later. They may also pretend to hide food in order to confuse potential thieves, which researchers believe shows an advanced level of cunning and intellect.

No. 6 - Pig

Despite a reputation for gluttony and poor hygiene, pigs are actually highly intelligent animals. Both domestic and wild species are known for their ability to adapt to a variety of different ecological conditions. They seem to be at least as trainable as cats and dogs, and certain domestic pigs have become a favorite pet in the U.S. Pigs are also extremely flexible. Unlike most other ungulates, which are strictly herbivorous, pigs and their relatives are omnivores with a diet that sometimes includes worms and small vertebrates. Where they have been introduced around the world, pigs tend to out-compete the native species. Though devastating to the native species, this trend is yet another strong indication of pig cleverness.

No. 5 - Crow

Crossing the street against traffic may be called "jay-walking," but jays and other members of the crow family understand better than some humans the importance of waiting for the light to change. Crows living in urban areas are known to gather nuts from trees and then place them in the street for passing cars to crack open the shells. Then, after waiting patiently for the light to change, they return to the street to retrieve their nutty snack - an impressive example of animal innovation. Crows also communicate in elaborate population-specific dialects and play games and tricks on one another. Some scientists even believe that crows are more intelligent than primates.

No. 4 - Elephant

Contrary to popular perception, elephants are more than just lumbering giants with big ears and a good memory. In fact, elephants are quite elegant, cultured and curious. They have been known to clean their food and use tools in various ways in the wild, and they can also follow human commands in captivity. Elephants are also extremely caring and empathetic to other members of their group and to other species, which is considered a highly advanced form of intelligence.

No. 3 - Orangutan

The great apes are considered the smartest creatures after humans. Of course, humans are biased in this regard, but the intellectual capacity of the great apes is difficult to deny. Among them, orangutans stand out as being especially gifted in the brains department. They have a strong culture and system of communication, and many have been observed to use tools in the wild. Orangutans live in widely scattered communities and form strong social bonds, which may be the key to their advanced cognitive skills. Females remain with their young for many years, teaching them all they need to survive in the forest.

No. 2 - Dolphin

Have you ever wondered why dolphins and other cetaceans are the star attraction at most aquariums? It's because they're smarter than almost any other creature on the planet. Dolphins are extremely social animals. Schools of dolphins can be observed in the world's oceans surfing, racing, leaping, spinning, whistling and otherwise enjoying themselves. They also have a sophisticated "language," though humans have only begun to unravel it. Dolphins use tools in their natural environment and can learn an impressive array of behavioral commands by human trainers. Like many of the most intelligent animals on Earth, dolphin females remain with their young for several years, teaching them all the tricks of the dolphin trade.

No. 1 - Chimpanzee

Topping our list of smartest animals is another great ape, the chimpanzee. The impressive intellectual abilities of this animal have long fascinated humans. They can make and use tools, hunt collectively, and are capable of advanced problem-solving. They are also able to learn sign language to communicate with humans and can remember the name sign for individuals they have not seen for several years. But perhaps the most amazing feature of the chimpanzee is its ability to use symbols for objects and combine the symbols in a sequence to convey a complex idea. Such intellectual gifts are probably central to maintaining this animal's complex social groups, where they form strong bonds and observe elaborate hierarchical structure.