The phrase 'smart animal' tends to bring a few old standbys to mind, like bottle-nose dolphins or chimpanzees. While they are definitely uncannily intelligent, they are also far from the only animals that display such mental prowess, even if a rat's never going to be as cute as a chimpanzee.
10 White-Mustached Portia Spiders
Believed to be the smartest spider on the planet, the White-Mustached Portia's a jumping spider that uses its intelligence to catch and eat other spiders. Native to forests in Africa, Asia and Australia, when scientists tested this spider, it showed exceptional problem-solving skills, able to deduce effective hunting strategies for spiders that it has never encountered. The spider can also hunt selectively, picking one spider over another to hunt and eat, as well as choose particular hunting grounds. It's also more patient than most people, willing to wait for hours for its preferred prey to arrive. Skilled in deception, one of the spiders' preferred tactics is to pluck on its prey's webs in patterns that mimic trapped bugs.
9 California Sea Lions
Sea lions are better known for their smell and barking than for their intelligence, but maybe we should rethink this. Studies on sea lions have shown that they are emotionally intelligent enough to recognize others' relationships by the similarity of their interactions with those in their own relationships. They also can be trained to recognize simple syntax and sign language, as well as to bob in time to a rhythmic beat- essentially, sea lions can dance, which is something usually seen in humans and mimicking birds. They also have a good memory, able to perform tricks after a three month lull in performing that particular trick. The intelligence of the sea lions was used by the U.S. Navy in the Persian Gulf to attach clamps to enemy divers' legs, by which they could be dragged onto boats.
The omnipresent city bird, with their tiny heads and wobbling gait are hardly creatures that pop to mind when someone says 'smart animals'. But appearances can be deceiving. The pigeon is one of the few animals that can pass a mirror test- that can recognize that their reflection is just that, a reflection. The pigeon's 'homing' in on a location is also impressive- while it may be similar to other birds' migrations, it is far more flexible. They can differentiate between other pigeons, and their reaction to the other pigeon varies depending on the behavior the other demonstrates. They have also displayed the ability to split their attention on a task, to focus on different aspects of the same problem. And they can be taught to appreciate art: a 1995 study taught pigeons to differentiate between Picasso and Monet's paintings, which then translated into the ability to differentiate between cubist and impressionist paintings (the authors of the study were awarded that year's Ig Noble Prize in Psychology).
7 Peregrine Falcons
The peregrine falcon, part of the fast-flying, hunting falconidae family, besides being deadly to any small animals unable to evade their 200 mph dives, are also pretty smart. They consistently score highly on the Avian IQ Index, developed by Dr. Louis Lefebvre, which uses the bird watching public as data collectors. The skill that separates the falcon from its more featherbrained cousins is its memory. The birds' impressive memory has made it easy to train for the centuries-old art of falconry.
Rats don't have a good rap. Which is too bad, because they're highly intelligent, social animals. Rats have clearly and repeatedly demonstrated the ability to learn, which has made them popular in scientific testing. In 2007, it was revealed that rats had metacognitive capabilities: the ability to reflect on their own knowledge, which is impressive, considering how many politicians haven't shown similar abilities. But what's really impressive about rats is how actively social they are. A 2011 study observed rats demonstrating altruistic behavior: in tests all female rats and seventy percent of male rats would free a trapped rat. When food was introduced into the equation, the rats tended to free the trapped rat first, and then go to the food- which they would then share with the trapped rat. To further cement their intelligence in the same study, the free rats rarely opened containers containing a toy rat, demonstrating the ability to differentiate between a live rat and an object that merely looked like one.
If you've ever been called one of the sheeple, or something similar, take heart. Being compared to a sheep might not be that bad after all: they've got great facial memory, remembering the faces of other sheep and humans for up to three years, and can recognize different emotions on these faces. They can also mentally map out their surroundings, and anecdotal evidence claims they have rudimentary problem-solving abilities, citing a particular flock in the UK that found a way around cattle grid. And the foolish flock behavior? Dr. Jennifer Morton explains that sheep behave differently in a flock than in one-on-one situations, just like most people.
The main sapient behavior we attribute to elephants is their memory, but there's more to these animals than just exceptional recall. They're empathic, capable of comforting one another, and can apparently recognize elephant bones, as wild elephants spend up to twice as long investigating elephant skulls as compared to other species. They're also competent problem solvers, capable of fashioning and using tools to achieve their ends. Using tools is impressive, but perhaps more so is their ability to combine problem solving with cooperation. In tests that required elephants to work together, they quickly figured it out, even to the point of patiently waiting for a helper to arrive.
If you're worried that you might not be able to eat a highly intelligent animal, and love bacon, just hit next now. Still here? Pigs are really smart: they are able to quickly learn new tasks and routines, even playing simple video games. And like people, they can get stuck in a rut, Dr. Suzanne Held of the University of Bristol explains that while they learn quickly, they can take much longer to unlearn something. A place where they were startled might become scarred into the pig's mind as a bad place to be avoided, despite the absence of actual danger. They've also displayed the ability to trick each other, in a test run by Dr. Mike Mendel, where smaller pigs learned to deceive larger pigs in order to get to food first.
If you've ever thrown anything at a crow determined to steal your food, I've got some bad news for you. The crow remembered your face- and shared it with its family, so they're all looking out for you. Crows are also capable of tool use, fashioning hooks to snag food, or dropping stones into a water-filled container to raise the water level enough for it to be able to nab treats floating on the surface. Beyond this, these birdbrains also have complex social behaviors that change as they age: young crows will make noise, to attract a group of youngsters to feed on a carcass, in order to defend against other scavengers, while adults tend to show up quietly in pairs, thus avoiding drawing other scavenger's attention to the food. They also play, as a variety of youtube videos will show you, something both charming and the hallmark of a creature smart enough to get bored.
Before we start: the acceptable plurals for octopus are 'octopuses' and 'octopodes', it's a Greek root, despite looking like a second declension Latin masculine noun. Now that we've gotten etymology out of the way, let's move on.
Boneless and brilliant, octopuses are capable of navigating mazes, quickly solving problems and remembering (for a while) the answers. They're smart enough to have preferences, as seen in an anecdote about Truman the Octopus, late of the New England Aquarium, explains that he took a dislike to a particular volunteer, shooting a stream of saltwater at whenever they came nearby, even if he hadn't seen them for months. They're certainly smart enough to make trouble- octopuses have been known to climb onto fishing boats to steal crabs from fishermen, or leave their tanks in zoos in order to snack on fish held in nearby tanks.