Bullfrogs: Studies have shown that bullfrogs don't sleep as we understand it. While they rest, they remain alert to stimuli while resting, suggesting that they don't engage in deep sleep.
Jellyfish: Despite lacking a brain or central nervous system, some species of jellyfish will exhibit resting states, but whether this can be considered true sleep is controversial. They will reduce their activity, but without a brain, it's unclear if this is true sleep.
Elephants: African elephants are known to sleep only about 2 hours a day, usually while standing up. In the wild, especially when migrating or under stress, they can go days without sleeping.
Alpine Swifts: These birds can fly for months at a time without landing, and while they are thought to take short naps while in flight, this is not sleep in the traditional sense, as they remain in flight.
Dolphins: Dolphins use unihemispheric slow-wave sleep, where one hemisphere of the brain is active while the other is resting. This allows them to maintain bodily functions such as swimming and surfacing to breathe while in a "half-asleep" state.
These animals have developed unique adaptations through evolution that allow them to survive with little or no sleep.