According to a study in 2017, the jellyfish enter into a situation which is a sleep-like state. During this, their activity decreases and have slower responsiveness to stimuli.
New-born dolphins don't sleep for a month after birth and stay alert with at least one eye open at all times
Bullfrog stay awake and alert even when they seem to be resting. These frogs don't sleep for a major period in a year and even when they rest after this, it's not complete sleep.
Female fruit flies exhibit brief sleep durations, with an average of 72 minutes per day. Some flies have been observed sleeping for as little as 4 minutes daily.
The great frigatebird, like dolphins, can engage in unihemispheric sleep. However, unlike dolphins, they use this strategy as needed
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