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.

There are tens of thousands species of fish around the world, whether it's in an aquarium, river, lake, or ocean. Like all animals (and humans), every single one needs some form of rest for cognitive ...

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 ...