Are there any animals that never sleep?

Answer 1

Fish.

Answer 2

All animals sleep.

Animals vary widely in their amounts of sleep, from two hours a day for giraffes to 20 hours for bats. Generally, required sleeping time decreases as body size increases. Cats are one of the few animals that do not have most of their sleep consolidated into one session, preferring instead to spread their sleep fairly evenly throughout the day. Water mammals "sleep" with alternate hemispheres of their brains asleep and the other awake. They need to do this so they can breathe above water while sleeping. Migratory birds also seem to sleep this way.

Even fish and fruit flies appear to have a "sleeplike" state. This alternation of the sleeplike state and its absence is referred to as a "Basic Rest and Activity Cycle", or BRAC. Since the modern definition of sleep is defined using EEG criteria, and such tiny brains preclude the recording of EEG's, this may not technically be described as sleep. However, if fruit flies are repeatedly disturbed so that they can not rest, they have what is referred to as a "rest rebound". This behavior is strikingly similar to that exhibited by mammals and birds in similar conditions. Many animals hibernate in a deep sleeplike state during winter to conserve body heat and energy. Estivation is a similar state in which other animals hibernate to escape the heat of summer.

Cattle, horses, and sheep are unique in that they can sleep while standing, though none may experience REM sleep in this position, for REM sleep causes partial muscle paralysis. For REM sleep to take place, the animals must lie down. Conversely, birds may have periods of REM sleep while perched. Some breeds of dogs usually sleep throughout the day like cats, while other breeds have only one daily sleep session. While dreaming, dogs and cats sometimes make a quiet barking sound or make running motions with their legs.

Answer 3

No. Until about 20 years ago it was believed that sharks had to continue swimming or they would die. This was proved false when they were filmed in a resting state. All animals must rest in order to survive.

Answer 4

none

(Sharks rest in a different way. They can rest part of their brain while still swimming along, semi-aware of what's around them. Sharks that are able to stop swimming will settle on the seabed, and species like the British Bullhuss shark actually close their eyes - so they appear to sleep like we do.)

Answer 5

Sharks

Answer 6

Fish

Answer 7

To my knowledge, no. Even fish have 'resting states' similar to sleep.
I have heard of some animals that have developed the ability to rest half their brains at a time.

Answer 8

The Bullfrog

Answer 9

Giraffs only sleep for a couple seconds at a time, some sharks don't.

Answer 10

Brainless animals like sea anemones don't sleep.