How do sharks sleep ?

Question

do they sleep upside down or what ?

Answer 1

The two answers above me?  Wrong.

Answer 2

they do not sleep upside down. im not sure about other sharks but i know that nurse sharks sleep in coral, in groups, on the sea floor. its something like that.

Answer 3

They don't sleep. They will "rest" for short periods of time in which they do not eat or do anything that would be physically exhausting, with the exception of swimming. They must keep moving or they drown; they need water to pass over their gills.

Answer 4

They sleep as they normally swim but staying at one place. But you wont know whether they are sleeping or awake because they dont have eyelids so they don't close their eyes.

Answer 5

By swimming .ie. moving, water flows through their gills constantly replacing their oxygen levels. If they stopped swimming and were motionless, the water wouldn't leave their gills fast enough not to upset their balance, so too much would accumulate. The laws of gravity would take over meaning they would sink and drown. That's why you never see a shark NOT moving.

Being upside down would probably affect their gills and the aerodynamics of their body shape.

Their brain can partially shut down, so they go into a sort of suspended hibernation, while still swimming.

Answer 6

It is unclear how sharks sleep. Some sharks can lie on the bottom while actively pumping water over their gills, but their eyes remain open and actively follow divers. When a shark is resting, it does not use its nares, but rather its spiracles. If a shark tried to use its nares while resting on the ocean floor, it would be sucking up sand rather than water. Many scientists believe this is one of the reasons sharks have spiracles. The spiny dogfish's spinal cord, rather than its brain, coordinates swimming, so it is possible for a spiny dogfish to continue to swim while sleeping.

It is also possible that a shark can sleep in a manner similar to dolphins. In this situation, one half of the brain sleeps at a time, thereby allowing the shark to be half conscious while sleeping.

Answer 7

A shark's movement is like our breathing. We need to do it to survive while we're asleep, and we don't have to be conscious to do it. Most sharks are not capable of pumping water into their gill slits (think of a fish flapping their gills), so they have to keep moving in order to have a constant supply of water and oxygen. Therefore, as they sleep, their movement is basically on auto-pilot, and they appear to be awake.

Answer 8

Fish don't sleep in the same way that we do, but they have active and inactive periods. Some sharks (like the nurse shark) have been observed resting motionless on the sea floor. Others have to keep moving in order to breathe.

Answer 9

not sure bout sharks and what position they sleep in, but dolphins rest one side of their brain at a time (so are like half asleep) and just drift thorugh the water. but because they are only 'hlaf' asleep they are aware if there is any danger.

could be the same with sharks.