A large group of yellowfin tuna swimming off the coast of Italy. Like all fish, they sleep, but it’s not like human sleep.
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Just about every creature on Earth needs to grab some Zs from time to time. Imagine trying to doze while dodging great whites and killer whales.
Octopuses might be able to dream.
Shutterstock/Henner Damke
Colour-changing patterns in snoozing octopuses are characteristic of two alternating sleep states.
We know that lots of animals, maybe all animals, sleep. Cats, dogs, even worms and jellyfish sleep. But we still don’t know exactly why they started sleeping.
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Pond snails use things like rocks or the side of their aquarium as their bed, attaching themselves while they sleep. This might not seem very relaxing but their shells do hang away from their body.