There are 35,000 kinds of fish living today, more than 3 trillion of them.
Swim in hot springs, rivers, ponds, and puddles worldwide. They swim in fresh and saltwater.
Three basic species of fish exist: bony fish like trout and sardines, jawless fish like the slimy hagfish, and sharks and rays with cartilage skeletons.
Everyone needs rest. Humans and haddock both need sleep. It provides the body and brain time to heal and recharge.
As a marine scientist, I wonder how fish relax. In every body of water, predators wait to consume them. They survive, like most life on Earth.
People are very out while sleeping. A loud noise may wake you awake, but you're otherwise unconscious