A protective mucous cocoon surrounds this parrotfish as it sleeps in Australia's Great Barrier Reef. This layer of protection helps fend off predators so parrotfish can get a good night's rest.

Do fish with no eyelids sleep? Given that they spend their entire lives submerged in water, this is a reasonable question to ask. Do fish with no eyelids sleep? Given that they spend their entire ...

Tom has a Master's degree in Journalism. His editorial work covers anything from archaeology and the environment to technology and culture. Tom has a Master's degree in Journalism. His editorial work ...

Contrary to common belief, not all vertebrates regulate their sleep-wake rhythm in the same way. University of Basel researchers have discovered that some fish – unlike humans – do not need orexin to ...

Sleep is one of life’s most universal behaviors. Despite its ubiquity, it’s also one of the most mysterious. Humans spend ...

Betta, or Siamese fighting fish, are one of the most popular aquarium fish in the world. Originating from southeast Asia, betta fish are known for their diverse range of colors with over 70 different ...