some sharks have full visability in there eyey so they are esential but other sharks such as the great white and the mako can only see in contrast so they eyes arn't as usefull but still needed
i wouldn't say all sharks do i think some close their eyes the same way you want to taste a type of food for the first time some close their eyes and some leave their eyes open
yes they do because they are afraid that the person is going to poke their eyes out
So they won't hurt their own eyes.
Sharks do not sleep
Blind sharks got their common name because they close their eyes when they are taken out of the water.
There are only a couple that don't attack human but Great White Sharks, Tiger Sharks, Bull Sharks and The Hammerhead Sharks are the most common to attack human but others may if you look like pray
great white sharks roll there real eyes back and when they attack they turn blackThe eyes actually do not roll back, a protective membrane covers them making it look that way.
sharks cannot sneeze. since sharks live in waterthey use their nose (irnot their eyes) to sence and catch prey. a sharks nose is equiped toopen and close at will when not in use.
The eye can stop seeing if you go blind. Fish can't close their eyes because they don't have eye lids (exception to some sharks) to close them with.
If feel of being threatened. They don't attack without reason . Plus they roll their eyes back for protection so they don't get harmed.
Yes, sharks will attack people whether they are white OR black. But sharks tend to attack white people more.
sharks
Even though sharks are among very few fish which have eyelids, they do not blink. Most species of sharks have special nictitating membranes which go over their eyes to protect them when they are hunting or under attack.
YES
no most sharks do not attack humans unless they do something to provoke them