Octopuses(章鱼) are some of the cleverest animals on the planet! So what makes them so smart? Let’s focus first on their defense mechanisms. Faced with multiple predators(捕食者)—including fish, birds and whales—octopuses are masters of disguise.They can imitate their environment by changing their skin colour.

Without a shell, octopuses are weak and easily hurt physically, and always try to remain hidden in a shelter such as a hole or the space beneath a rock. Some prefer to wrap themselves in shells and small stones, while others transport their shelters in their arms. This is the case for the coconut octopus, which,true to its name, has been observed carrying coconut shells around to hide within in case of danger.

Octopuses are also fearsome predators themselves, and their attack mechanisms are suited to the wide variety of prey(猎物) they consume, including seashells,fish and even other creatures like them. They can use their vision and camouflage skills to hunt, and their arms to explore,touch and taste their environment to seize every bit of food within reach.

Octopuses can also use conditional discrimination, that is, they can change their choice depending on the situation. For example, they can learn to attack an object only in the presence of bubbles. They can also use space learning, and find a hidden shelter by remembering its position. Last but not least, octopuses can learn by watching other octopuses carry out tasks, such as choosing one specific object over another. This is surprising,because they are mainly solitary(独居的)creatures.

Octopuses meet every criteria for the definition of intelligence: They show a great flexibility in obtaining information (using several senses and learning socially), in processing it (through discriminative and conditional learning), in storing it (through long- term memory) and in applying it toward both predators and prey.

Although it's tricky for people to see, mouse feelings are written all over their little faces. A research team in Germany designed a computer program to study the faces of mice for signs of feelings. It was able to reliably spot expressions of joy, fear, pain and other basic feelings. Those signs offer a sort of "field guide" for scientists who study feelings. And understanding the feelings in animals better could help guide human studies too, the researchers say.

German scientist Nadine Gogolla studies the brain. She and her colleagues treated mice in ways to cause different feelings. To bring about pleasure, they gave the mice sugar water. A shock to their tails resulted in pain. And being put somewhere they had been shocked in the past led to fear. High-speed video cameras focused on the animals' faces. They recorded tiny movements in the animals' ears, noses, whiskers and more.

An observer would likely see that a mouse's face changes. But translating those small changes into feelings is really hard. That's true especially for an untrained human being.

But a computer had no trouble, the researchers found. They used an approach called "machine learning." It directs a computer program to detect patterns in videos. The program analyzed thousands of videos of mouse faces. It spotted tiny movements that accompanied good or bad events. For example, when a mouse is drinking sweet water, its ears move forward and fold toward the body. At the same time, its nose moves down toward the mouth. Its face looks differently when the mouse tastes bitter water. Its ears move straight back. Its nose curls slightly backward, too.

The activity of nerve cells in a mouse's brain also changed with various feelings, other analyses showed. These cells live in a region known as the insular cortex. This deeply buried spot plays a role in human feelings, too.

Some scientists believe that one of the most intelligent beings on Earth is in fact the octopus (章鱼).

Octopuses usually live at the bottom of river mouths and seas-areas which are not attractive to researchers. They are not social animals so it can be hard to study their interaction with others. And the octopus’ intelligence is not easy for humans to understand. When we observe some animals such as rats or dogs, we can often understand their behavior. Octopuses，however can seem like aliens (外星人). Scientists need to have a lot of imagination to understand what an octopus is thinking!

In the 1950s, the US Air Force sponsored scientists to study the way octopuses use their brains. They hoped that they could use this knowledge to help them build better computers. However, their brains were so complex that the scientists felt it of no significance to continue with it. Octopuses have a very complex nervous system and recent research suggests that they have some of their intelligence inside each arm, which means that each arm can “think” for itself. It also appears that they have a good memory, perhaps similar to a cat’s.

Perhaps the most striking thing about octopuses is their ability to change their color and body pattern. They do this to camouflage themselves to avoid their enemies and also to communicate with others. They can completely change their appearance in less than a second. It can change its skin to look like rocks, sand or planktron (浮游生物).

Some scientists have even suggested that these different patterns and colors are in fact a very hard language-and that each design is a different verb，adjective or noun. But nobody has been able to work out what they might be saying. There’s a long way to go to get to know the octopus completely.