Giraffes can go weeks without sleep. Scientists think that since they are so large and slow, not sleeping helps them keep an eye out for predators. On average though, they get about 20 minutes per day!
Some desert snails can sleep for years! An Egyptian desert snail was once assumed dead and placed in a museum. Four years later, it popped out of its shell and crawled away!
Flamingos sleep while standing up, but not for the same reason as horses or zebras (because of predators). It's usually because there simply aren't too many comfortable places to lie down in their normal habitat.
Since sharks have to keep moving in order to get oxygen through their gills, scientists believe that most species may be able to put their brains to sleep but continue swimming.
Frogs undergo a particularly intense form of hibernation. While most of their body freezes and their lungs even stop breathing, high concentrations of glucose in their vital organs prevent the essential parts from freezing.
Some animals (like rodents) can sleep for half the year! It's called hibernation and allows the animal to survive through periods of cold or insufficient food.
Bats can sleep up to 20 hours per day! They also sleep upside down because it's easier for them to take off from that position. (Their wings are rather weak.)