Is it true that if a shark stops swimming it'll die?

Question

If so how come, and how do they sleep?

Answer 1

It was once believed that all sharks had to swim constantly in order to breathe and could not sleep for more than a few minutes at a time. Oxygen-rich water flows through the gills during movement allowing the shark to breathe. While some species of sharks do need to swim constantly, this is not true for all sharks. Some sharks such as the nurse shark have spiracles that force water across their gills allowing for stationary rest. Sharks do not sleep like humans do, but instead have active and restful periods.
http://www.flmnh.ufl.edu/fish/sharks/nsrc/Basics.htm#sleep

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. 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 with only parts of its brain in a manner similar to dolphins.
http://en.wikipedia.org/wiki/Sharks#Shark_sleep

It depends what you mean by sleep. When humans sleep we are not conscious of what is going on around us, we kind of shut-down for a while and are not able to walk around unless we happen to be sleep-walking. Sharks rest in a different way. They can rest part of their brain while still swimming along, semi-aware of what's around them. Sharks that are able to stop swimming will settle on the seabed, and species like the British Bullhuss shark actually close their eyes - so they appear to sleep like we do. In our aquarium I have seen two Sandtiger sharks bump into each other nose-to-nose. They were so startled, they both took off at great speed in opposite directions. This suggested to me that they were dozing on the move and not paying full attention to where they were going, but I have never seen them bump into the sides of the tank when snoozing, so they normally seem to have an idea of where they are. A lot of research has been done on sleep in humans, and many mysteries still surround sleep and its importance to healthy living, but conducting similar research on sharks is almost impossible for practical reasons, we have a lot to learn about sleep and its purpose in fish and other animals.
http://www.national-aquarium.co.uk/databases/FAQsLibrary/index.asp?FAQCategoryID=&FAQID=767&Sear

Answer 2

Strictly speaking this is a common misconception, the reason a shark seems to always be moving is the necessity to have a constant and sufficient water flow over and through its gills in order to extract the oxygen it requires. This is normally done by swimming although if the current or other forms of water movement are sufficient, then forward movement is not necessary. Sharks, like many animals do not sleep in the conventional way, but instead will slow their pace and cease all but essential activities and may appear to be in a trance like state or 'sleep'.

Answer 3

There are many species of bottom dwelling shark have "gill pumps," muscles that contract and pass water over the gills, such as the nurse shark. However, most streamlined sharks rely on ram-ventilation, which means they have to keep moving to pass water over their gills to breathe.

There is also the case of the "sleeping sharks of Isla Mujeres," sreamlined sharks resting on the botom of a cave off the coast of Mexico. They're not really sleeping in a technical sense because their eyes have been observed to follow divers swimming near them. Five species have been identified to be resting on the cave floor. It is suspected that the caves have a high enough oxygen concentration and strong enough current to keep water passing over their gills while they remain motionless.

Whether or not sharks sleep is unknown. From a series of experiments done on a certain species of shark, it was discovered that the part of the nervous system that controls swimming coordination in a shark is located in the spinal chord, not the brain. So it is possible for parts of a sharks brain to "shut down" and rest while swimming.

Answer 4

Not neccisarily. Some types of sharks have gills powerful enough to move on their own so they can breathe while they sleep. Other sharks don't have gills that strong. They have to find a strong enough current and sleep there for a couple of hours then move on or they will die.

Answer 5

No they won't die, at least not instantly. Sharks don't have a swim bladder that other fish have. The swim bladder is like a balloon full of air that helps keep fish afloat, so they don't need to swim constantly. If a shark stops swimming it will sink, not die.

Some sharks live on the sea bottom and therefore don't need to worry about sinking.

Answer 6

Well, if it stops moving, not swimming. It needs the water to run over their gills. Some sharks have special respiratory systems where they do not have to move. Sharks don't sleep like we do, they have active periods, and restful ones.

Answer 7

no, it is not true. Many sharks will lay stationary on the sea floor to rest. However, they always lay facing a current so that water is running through their gills in order for them to respirate while they are stationary. Nurse sharks are notorious for this.

Answer 8

I don't think that is true, at least not for all species of shark.

"Sharks need to ventilate their gills with water in order to get enough oxygen - without oxygen they effectively suffocate. Some sharks are able to do this by pumping water through their mouth whilst lying still but many need to keep moving."

Answer 9

Yes i think it is true because they need water flowing through their gills constantly. The female shark is the only one that stops swimming, when they are giving birth.

Answer 10

Sharks don't sleep, they don't need to.

A shark does not need to move all the time to stay alive, but if it is still and is in still water it can not respire effectively through its gills and as such will eventually die, however sharks have slow metabolisms and as such don't need to respire as much as many animals do so can do several minutes without oxygen before death.
So no it will not die, in moving water it will survive indefinitely and in still water it will not die for several minutes.

Also - cool fact: sharks can not die of old age! They live until disease, injury, starvation or something else kills them but don't die of old age ever! Isn't that amazing!!!